JPH06233052A - Image reader - Google Patents

Abstract

PURPOSE:To read an image with a high precision and a high quality in a simple constitution by using photoelectric transducers different in limits of measured light quantity and selecting photoelectric transducers in accordance with the quantity of light to be measured. CONSTITUTION:When reflected light from a document or light transmitted through the document is photoelectrically converted and is read to read the image on the document, the image light, is divided by a half mirror 62 where ratios to the quantity of transmitted light and that of reflected light are different to use two photoelectric transducers 64 and 66 which are made different in saturation quantities of light to the image light. When the quantity of the image light is small, the image is read by the photoelectric transducer 64 whose saturation quantity of light is smaller, and the image is read before saturation of this photoelectric transducer 64, and it is switched to the photoelectric transducer 66 whose saturation quantity of light is larger. Thus, the dynamic range of image read is extended, and the whole of a picture density area to be recorded on a film is read with a high resolution by one main scanning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention photoelectrically converts an image carried on a reflective original such as a photograph or a printed matter, a transparent original such as a negative film or a reversal film to read it, or further processes the read light amount data. The present invention relates to an image reading apparatus that outputs image information as image information. More specifically, the present invention relates to an image reading device that has a simple configuration and operation, is inexpensive, and can obtain a high-quality printed image.

[0002]

2. Description of the Related Art In recent years, image information recorded on photographic film (hereinafter referred to as film) such as negative film and reversal film and printed matter is photoelectrically read, and the read image is converted into a digital signal and then variously read. 2. Description of the Related Art Development of a digital photo printer in which image processing is performed to obtain image information for recording, and a photosensitive material such as photographic paper is scanned and exposed by recording light modulated according to the image information to produce a print is in progress.

A digital photo printer is a print image editing layout such as editing a combination of a plurality of images and dividing an image, editing characters and images, color / density adjustment, scaling ratio, and the like.
Various image processing such as contour enhancement can be performed freely,
It is possible to output a finished print that has been edited and image-processed freely according to the purpose. Also, in conventional printing by surface exposure, it is not possible to reproduce all the image density information recorded on a film or the like in terms of density resolution, spatial resolution, color / density reproducibility, etc. For example, it is possible to output a print that reproduces almost 100% of the image density information recorded on the film.

Such a digital photo printer is basically a reading device for reading an image recorded on a document such as a film, a set-up device for image-processing the read image to determine subsequent exposure conditions, and the determined device. The image forming apparatus is configured to scan and expose a light-sensitive material according to the above exposure conditions to perform development processing.

In a device for reading an image recorded on a film or the like (hereinafter referred to as a film), for example, in reading by slit scanning, the film is irradiated with slit-shaped reading light extending in one-dimensional direction and Is moved in a direction substantially orthogonal to the one-dimensional direction (or the reading light and the photoelectric conversion element are moved), so that the film is two-dimensionally scanned by the reading light. The transmitted light carrying the film image transmitted through the film is imaged on the light receiving surface of a photoelectric conversion element such as a CCD line sensor, photoelectrically converted and read. The read light amount data is amplified, converted into a digital signal by A / D conversion, subjected to various image processing such as correction of characteristic variations by each CCD element, density conversion, and magnification conversion, and transferred to a setup device. To be done.

In the setup device, the transferred image information is reproduced as a visible image on a display such as a CRT. The operator looks at the reproduced image and, if necessary, further corrects gradation correction, color / density correction, etc., on this reproduced image (setting of setup conditions), and the reproduced image passes as a finished print (verification OK). If there is, it is transferred to the image forming apparatus as image information for recording.

In the image forming apparatus, if the image recording by raster scanning (light beam scanning) is used, exposure of the three primary color photosensitive layers formed on the photosensitive material, for example, three colors of R, G and B is performed. Are modulated in accordance with the image information for recording to be deflected in the main scanning direction (corresponding to the one-dimensional direction), and the light beams are exposed in a direction substantially orthogonal to the main scanning direction. By sub-scan transporting the material (relatively sub-scanning the deflected light beam and the photosensitive material), the photosensitive material is two-dimensionally scanned and exposed by the light beam modulated according to the recorded image, The image of the read film is recorded on the light-sensitive material.

The exposed light-sensitive material is then developed according to the type of light-sensitive material. For example, in the case of a silver salt photographic light-sensitive material, development processing such as coloring / development → bleaching / fixing → washing → drying is performed to obtain a finished product. It is output as a print.

[0009]

In order to realize a high quality finished print with such a digital photo printer, it is necessary to use a photoelectric conversion element having both high spatial resolution and high density (light quantity) resolution. For example, CCD Sensors are used well. The range of image density D (= logE) recorded (recordable) on a negative film is generally about 3.2, while the range of image density D recorded on a reversal film is about 3.8. Images in a wide density range can be recorded. However, in general, a photoelectric conversion element excellent in space and density resolution has a narrow measurable density range (dynamic range), and it is difficult to measure the entire density range of a negative or reversal film as described above.

Therefore, in the conventional image reading apparatus used for a digital photo printer or the like, in order to determine the reading density range by the photoelectric conversion element, the dynamic of the photoelectric conversion element is read before the image reading of the film for printing. Pre-reading (pre-scanning) for roughly reading the image on the film is performed with the range widened, and the range of the density read by the CCD sensor during the main reading (main scanning) is determined according to the result of the pre-scanning. .

That is, in the conventional image reading apparatus, the reading of the film image is performed in the procedure of "prescan → determination of reading density range → main scan", but the reading is restarted after the prescan is performed. After returning the film or reading light source and CCD sensor to the state,
The main scan is performed, the reading efficiency of the film image is further reduced, and the movement of the film (or the reading light and the CCD sensor) is complicated, which complicates the device configuration and operation and increases the cost of the device. I am

Also, as described above, the photoelectrically read light amount data is amplified and A / D converted. However, in order to obtain image information with high accuracy and output a high-quality finished print, it is necessary to obtain image information with a density resolution of about 0.01. Here, in order to read the density range of 3.0 with a resolution of 0.01, a high-performance A / D converter of 16 bits or more is required, and the read density range is set to 2.0 by prescan. Even in such a case, a 13-bit high-performance A / D converter is required.

Such a high performance A / D converter is extremely expensive, and the conventional A / D converter takes a long time to process. Further, it is difficult to avoid that a 16-bit A / D converter capable of high-speed A / D conversion has not yet been put into practical use, or even if put into practical use, it will be extremely expensive. Therefore, at present, low-speed processing by an A / D converter of 14 to 16 bits or deterioration of image quality by A / D converter of 8 to 12 bits is performed.
One of the high-speed processings by the D converter is selected, which causes the reading time to be long and the quality of the reproduced image to be deteriorated. Therefore, it is possible to realize an image reading apparatus capable of high-speed and high-precision image processing. Is desired.

Further, when outputting an image read by such an image reading device to a finished print, characters may be input at the stage of image signal processing in addition to the image carried by the original depending on the use of the finished print, In many cases, characters are output in a region different from the image, or characters are overwritten on the output image. Here, when digital image processing is performed, when the characters are recorded on the finished print and the spatial resolution is low (the number of pixels is small), the reproduced characters become jagged, resulting in a high-quality finish. The print cannot be output.

If the spatial resolution (the number of output pixels) of image information is improved in order to improve the image quality of characters, it is necessary to increase the capacity of the frame memory and the like accordingly, which greatly increases the cost of the image reading apparatus. Will be invited.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to obtain a high-quality finished print with an inexpensive and simple structure, which enables high-precision, high-quality image reading. An object of the present invention is to provide an image reading device capable of performing the above.

[0017]

In order to achieve the above object, the first aspect of the image reading apparatus of the present invention is characterized in that the reflected light from the document or the transmitted light of the document is photoelectrically converted and read. An image reading apparatus for reading an image carried by a document, wherein a plurality of photoelectric conversion elements having different measurement light amount limits and means for selecting the photoelectric conversion elements according to the measurement light amount or the measurement results by each photoelectric conversion element are added. And an image reading device.

In the first aspect of the image recording apparatus of the present invention, at least the upper limit portion of the measurement light amount region of the photoelectric conversion element having a low measurement light amount limit and the measurement light amount region of the photoelectric conversion element having a high measurement light amount limit are defined. The lower limit portion is overlapped, and the overlapped measurement light amount region is an amount corresponding to at least the required S / N ratio, and the S / N ratio is subtracted from the dynamic range of each photoelectric conversion element. It is preferable that the total sum is larger than the dynamic range required for image reading.

In a second aspect of the image reading apparatus of the present invention, the reflected light from the original or the transmitted light of the original is photoelectrically converted to read the image carried by the original, the signal processing is performed, and the image is output as image information. An image reading device is provided, which is characterized in that the light amount data read by photoelectric conversion is subjected to LOG conversion and then A / D conversion.

Further, according to a third aspect of the image reading apparatus of the present invention, the reflected light from the original or the transmitted light of the original is photoelectrically converted to read the image carried by the original, the signal processing is performed, and the image is output as image information. An image reading apparatus that has an image frame memory for temporarily storing image information and a character frame memory for temporarily storing character information,
Further, there is provided an image reading device characterized in that the character frame memory has a resolution at least twice that of the image frame memory in both the vertical direction and the horizontal direction of image information.

[0021]

The image reading apparatus of the present invention is used for a digital photo printer or the like, and is used for a transparent image recorded on a negative film or a positive film, or an image recorded on a reflective original such as a printed matter (hereinafter, referred to as an image). (1) is photoelectrically read by a photoelectric conversion element such as a CCD sensor, or the read light amount data is subjected to signal processing and output as image information. In such an image reading apparatus, the first aspect of the present invention uses a plurality of photoelectric conversion elements having different measurement light amount limits (saturation light amounts) and uses a light amount of light carrying image information (hereinafter referred to as image light). By selecting and using a photoelectric conversion element according to, it is possible to read images in a wide dynamic range,
In the second aspect, the light amount data obtained by measuring the image light and photoelectrically converting it is LOG-converted before the A / D conversion, so that the high-speed and high-speed operation can be achieved even if an inexpensive A / D converter is used. The third aspect enables accurate A / D conversion, and further has an image frame memory and a character frame memory separately, and the character frame memory has an image resolution higher than that of the image frame memory. The basic configuration is to make it possible to output high-quality characters in the finished print with a minimum cost increase by doubling at least twice in the vertical and horizontal directions of the information.

In order to obtain a high quality output image, a photoelectric conversion element having a high spatial resolution and a high density resolution is required, but as described above, such a high performance photoelectric conversion element generally has a dynamic range. However, it is difficult to measure the entire density range recorded on a document such as a negative film or a reversal film. In the conventional image reading device, prior to the main reading (main scanning) of the transparent original image, pre-reading (pre-scan) is performed to roughly read the image of the transparent original, and the image density of the main scan based on this data is read. Has determined the reading range. Therefore, the movement of the film (reading light source and photoelectric conversion element) and the device are complicated, the efficiency of image reading is poor, and
As described above, the cost of the device also increases.

On the other hand, in the image reading apparatus of the first aspect of the present invention, the image light is divided by a plurality of photoelectric conversion elements having different saturated light amounts, for example, half mirrors having different ratios of transmitted light amount and reflected light amount. By using the two photoelectric conversion elements having different saturated light amounts with respect to the image light (before division), when the light amount of the image light is low, image reading is performed by the photoelectric conversion element having a low saturated light amount, and The image reading is switched to the photoelectric conversion element having a high saturated light amount at the moment when the conversion element is saturated, immediately before the saturation, or before the photoelectric conversion element having a low saturated light amount is saturated. With such a configuration, the dynamic range of image reading can be widened, and the entire image density region recorded on the film or the like in one main scan without performing prescan can be performed with high spatial resolution. It is possible to read with high density resolution, the configuration and operation of the image reading device can be greatly simplified, and an inexpensive image reading device can be realized.

Further, preferably, at least the upper limit part of the measurable region of the photoelectric conversion element having a low saturated light amount and the lower limit part of the photoelectric conversion element having a high saturated light amount overlap with the light amount of the image light, and This overlapped portion corresponds to at least the S / N ratio required by the image reading device, and the sum of the values obtained by subtracting the required S / N ratio from the dynamic range of the photoelectric conversion element is sufficient for image reading. Configure so that the required dynamic range is exceeded.

That is, according to the first aspect of the image reading apparatus of the present invention, when the light amount of the image light is low as described above, the photoelectric conversion element having a low saturated light amount is used, and the light amount of the image light is changed according to the light amount. The image reading is switched to the photoelectric conversion element having a high saturated light amount. In the above configuration, however, the light amount of the image light incident on the photoelectric conversion element having a high saturated light amount corresponds to the required S / N ratio. The total of the dynamic ranges of the photoelectric conversion elements, which is equal to or more than the amount and the S / N ratio is subtracted, sufficiently covers the density range recorded on the document. Therefore, the photoelectric conversion element having a high saturated light amount needs to have the required S / N ratio at the time of starting the reading.
Since it is in a state of rising at a ratio or more and has a sufficient dynamic range for the original, excellent image reading with high precision, high spatial resolution and high density resolution can be efficiently realized with a sufficient dynamic range. .

Further, in such an image reading apparatus, the light quantity data of the image light read by the photoelectric conversion element is A / D converted and then subjected to image processing as digital image information to obtain a high quality finished print. Therefore, it is necessary to read an image with a density resolution of about 0.01, and for that purpose, an expensive A / D converter having a performance of 16 bits or more is necessary for reading the density range of 3.0, for example. In addition, there is a problem that A / D conversion takes a very long time. Therefore, at present, 1
A 6-bit A / D converter or the like is used to perform low-speed processing, or an 12-bit A / D converter is used to reduce image quality and perform high-speed processing.

On the other hand, the second embodiment of the image reading apparatus of the present invention.
In this aspect, the light amount data read by the photoelectric conversion element is first LOG-converted and then A / D-converted to perform various image processing. Therefore, 16 bits
A high-performance A / D converter such as
The D converter can perform high-speed and highly accurate A / D conversion, and the cost of the image reading device can be reduced.

Further, depending on the application such as a New Year's card, it is necessary to output characters in the finished print in addition to the image read from the original. Here, if only the image is output to the finished print, the number of pixels of the output image is about 300 dpi to obtain a sufficiently high-quality image, but at least 400 dpi, preferably 600 for obtaining high-quality characters.
When the number of pixels of dpi is required and the number of pixels of the output image is small, the reproduced characters become jagged and high-quality finished prints cannot be output, while the characters have high image quality. Therefore, if the number of output pixels of image information is increased, it is necessary to increase the capacity of the frame memory or the like accordingly, resulting in a significant increase in cost of the image reading apparatus.

On the other hand, the third embodiment of the image reading apparatus of the present invention.
In this aspect, an image frame memory for storing a picture and the like and a character frame memory for storing character information are separately provided, and the character frame memory has an image capacity larger than that of the image frame memory. It has at least twice the vertical and horizontal directions of information. Therefore, not only images but also high-quality finished prints in which high-quality characters are recorded can be output, and high image quality of characters can be achieved with a minimum cost increase, and high-quality image output is possible. Image reading apparatus can be realized at low cost. Moreover, since character information and image information are handled by different frame memories, it is possible to easily correct or rewrite characters.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The image reading apparatus of the present invention will be described in detail below with reference to the preferred embodiments shown in the accompanying drawings.
FIG. 1 conceptually shows an example of a digital photo printer using the image reading apparatus according to the first and second aspects of the present invention. In addition, in FIG. 1, the flow of the image information is indicated by a solid line.
The flow of the control signal is shown by a broken line, and the light is shown by a chain line.

Digital photo printer 1 shown in FIG.
0 is a full-color print image (output image) after reading the transmission image recorded on the developed negative film or reversal film of 24 sheets, 36 sheets, etc. one frame at a time and performing the necessary image processing. The image is recorded on the photosensitive material A by scanning exposure, and the finished print P is output by developing the image. Basically, the image is recorded on the exposed (roll) film F. Image reading apparatus 12 according to the present invention for sequentially reading and processing transparent images (hereinafter referred to as images), a simulation image of the read image is displayed, and quality inspection is performed to determine image forming conditions (setup). Set-up device 14 and the photosensitive material A exposed by scanning exposure of the photosensitive material A according to the image forming conditions determined by the set-up device 14. More comprised an image forming apparatus 16, finished prints P by developing the A.

In FIG. 1, the image reading device 12 is related to the image reading device of the present invention, and basically, the image reading unit 18, the input timing control unit 35, the CCD correction unit 32, and the density conversion unit 34. , And a magnification conversion unit 36. Such an image reading device 12 conveys the developed (roll) film F in the direction of the arrow a in the drawing,
The image recorded on the film F is photoelectrically read frame by frame, and the read image information is subjected to various image processes such as A / D conversion, measurement value correction, density conversion, magnification conversion, and sharpness. Image information setup device 14
Send to.

The image reading section 18 reads an image for output (printing), and has a high spatial resolution (for example, about 1100 pixels × 1700 lines for a 35 mm film) for an image recorded on the film F. ) And the density resolution are photoelectrically read and transferred to the CCD correction unit 32 as output image information. Such an image reading unit 1
Reference numeral 8 is basically an image reading light source 50, a filter unit 52, a light collecting unit 54, a conveyance roller pair 56, an imaging lens 60, a half mirror 62, a first CCD sensor 64, and a first CCD sensor 64. The 2CCD sensor 66 and the CCD control unit 30 are included.

The light source 50 emits the reading light for reading the image of the film F, and if it emits a sufficient amount of light for reading by each CCD sensor, it is an ordinary halogen lamp, a fluorescent lamp or the like. Any of various light sources used for image reading can be used.

The reading light emitted from the light source 50 then enters the filter section 52. The filter unit 52 is a functional filter 52A such as a heat insulating filter or an ultraviolet absorbing filter.
And a color filter 52F of three primary colors of cyan (C), magenta (M), and yellow (Y) are combined to remove unnecessary components such as ultraviolet rays and heat rays from the reading light incident on the film F. Also, the color / density of the reading light is adjusted as necessary.

The reading light that has passed through the filter section 52 enters the condenser section 54. The condensing unit 54 diffuses and condenses the incident reading light inside, and emits the reading light as slit-like reading light having a longitudinal direction in a direction substantially orthogonal to the scanning direction (direction of arrow a in the drawing) from the opening 54a. And makes it enter the film F. Needless to say, the slit-shaped reading light emitted from the light collecting unit 54 needs to be longer in the longitudinal direction than in the width direction of the film F.

The pair of transport rollers 56 sandwich the film F at a place other than the image area and have a predetermined transport speed in the scanning transport direction indicated by the arrow a, for example, when the film F is a 35 mm film, it will be described later. One image is read by the line CCD at 1700 lines and is conveyed at a predetermined conveying speed. A motor (not shown) serving as a drive source is engaged with the conveying roller pair 56 to rotate the film F at a predetermined speed. Transport. Here, as described above, since the reading light is in the form of a slit having a longitudinal direction in a direction substantially orthogonal to the carrying direction, the film F (image) carried in the scanning direction consequently covers the entire surface by the reading light. Two-dimensional slit scanning is performed.

The slit-shaped transmitted light T (that is, the image light carrying the image recorded on the film F) transmitted through the film F is then incident on the imaging lens 62. The imaging lens 62 receives the transmitted light T (transmitted light T ₁ and T
₂ ) is the first CCD sensor 64 and the second CCD sensor 6
Image at 6. The half mirror 62 arranged on the downstream side of the imaging lens 62 transmits about 97.8% of the transmitted light T,
The transmitted light T is split into 45: 1 by reflecting about 2.2%. The transmitted light T ₁ transmitted through the half mirror 62 is the first CC
The transmitted light T _{2 which} is incident on and reflected by the D sensor 64 is
It is incident on the CCD sensor 66 and the amount of light is measured,
The light amount data is sent to the CCD control unit 30. FIG. 2 shows a half mirror 62, a first CCD sensor 64 and a second CC.
A conceptual diagram of the D sensor 66 and the CCD control unit 30 is shown and will be described in more detail.

As described above, the half mirror 62 transmits about 97.8% of the transmitted light T passing through the imaging lens 60 and reflects about 2.2% of the transmitted light T to divide the transmitted light T into 45: 1. To do.
The illustrated digital photo printer 10 according to the present invention
In the (image reading device 12), the transmitted light T is thus divided into two with different light amount ratios, and thus the first CCD sensor 64 and the second CC for the transmitted light T before the division are obtained.
The measurement light amount limit (saturation light amount) of the D sensor 66 is made different. In the illustrated example, the division ratio of the transmitted light T is 4
Although it is 5: 1, this division ratio is determined according to the S / N ratio required by the image reading device 12 and the dynamic range required for image reading, and is not limited to this ratio. This point will be described later in detail.

The transmitted light T ₁ transmitted through the half mirror 62 enters the first CCD sensor 64 and is reflected by the transmitted light T 1.
₂ is incident on the second CCD sensor 66, and the amount of light is measured. The first CCD sensor 64 and the second CCD sensor 66 have the same structure, and are composed of, for example, three line CCDs corresponding to the three primary colors of R, G, and B, and transmitted light carrying a recorded image transmitted through the film F. An image recorded on the film F is read by spectrally converting T ₁ and T ₂ into three primary colors of R, G and B, and photoelectrically converting the respective light amounts to measure. For 35mm film,
One line (that is, the longitudinal direction of the slit-like transmitted light) is read by 1100 pixels.

As described above, since the transmitted lights T ₁ and T ₂ incident on both CCD sensors are divided into different light quantity ratios by the half mirror 62, the _first CCD for the transmitted light T before the division. Sensor 64 and second C
The saturated light amounts of the CD sensors 66 are different from each other, and as a result, the second CCD sensor 66 has 45 times the saturated light amount of the first CCD sensor 64.

Light quantity data of each of R, G and B of the transmitted light T ₁ and T ₂ photoelectrically measured by the first CCD sensor 64 and the second CCD sensor 66 (hereinafter,
The light amount data) is sent to the CCD control unit 30. The CCD control unit 30 includes the first CCD sensor 6 and
4 and the second CCD sensor 66 are provided correspondingly,
CDS (correlated double sampling) 20a and 20b,
Amplifiers 22a and 22b, LOG converters 24a and 24b, A / D converters 26a and 26b, and a first CC
And a selector 28 for selecting the light quantity data of the D sensor 64 and the 2CCD sensor 66, transmission light T ₁ and T
The light amount data of ₂ are noise-reduced by the corresponding CDS (correlated double sampling) 20a and 20b, and are amplified by the amplifiers 22a and 22b.

The light quantity data of the transmitted lights T ₁ and T ₂ amplified by the amplifiers 22a and 22b are LOG-converted by the LOG converters 24a and 24b, and then converted into digital image signals by the A / D converters 26a and 26b. To be done. In the second aspect of the image reading apparatus of the present invention, the light quantity data is LOG-converted before being A / D-converted as described above, so that a small and inexpensive A / D converter can be used for quick and high precision. A / D conversion can be performed, and the cost of the image reading device 12 can be reduced. This point will be described later in detail.

The digital image signal converted by the A / D converters 26a and 26b is then sent to the selector 28. The selector 28 has a first
The saturation detection signal s indicating that the CCD sensor 64 is saturated (or just before saturation) is the A / D converter 2
6a. In the state where the amount of the transmitted light T is low and the first CCD sensor 64 is not saturated, the selector 28
When the digital image signal from the A / D converter 26a, which is the light amount data from the first CCD sensor 64, is selected and sent to the CCD correction unit 32, and the saturation detection signal s detects that the first CCD sensor 64 is saturated, the second CCD sensor 64 is detected. The digital image signal from the A / D converter 26b by the sensor 66 is selected and sent to the CCD correction unit 32.

In the illustrated example, both the first CCD sensor 64 and the second CCD sensor 66 are composed of a line CCD of 1100 pixels, and the reading and processing of the transmitted light T ₁ and T ₂ by them are predetermined. The digital image signal is selected by the selector 28 for each pixel of the line CCD since it is sequentially performed for each pixel in accordance with the CCD clock rate.

As described above, in an image reading apparatus in an application such as a digital photo printer which is required to output a high quality finished print, it is necessary to read using a photoelectric conversion element having a high spatial resolution and a high density resolution. is there. However, such a high-performance photoelectric conversion element generally has a narrow dynamic range, and it is difficult to measure the entire density range recorded on a document such as a negative film. As described above, the range is determined, which complicates the configuration and the operation and increases the cost of the image reading apparatus. On the other hand, in the first aspect of the image reading apparatus of the present invention, such a configuration, that is, a plurality of photoelectric conversion elements having different saturated light amounts are used, and the photoelectric conversion device having a low saturated light amount according to the light amount of the transmitted light T is used. When the conversion element is saturated, the photoelectric conversion element used for reading is switched to one with a high saturated light amount to widen the dynamic range of image reading and to read the entire density area recorded on negative film etc. Therefore, the cost of the image reading apparatus capable of highly accurate image quality reading without prescanning or the like can be significantly reduced.

Here, in the image reading apparatus 12 (digital photo printer 10) of the illustrated example, as a preferable mode, at least the upper limit portion of the light amount measurement region by the first CCD sensor 64 having a low saturation light amount and the second portion having a high saturation light amount.
The lower limit part of the light amount measurement area by the CCD sensor 66 overlaps, and this overlapping part corresponds to at least the S / N ratio required by the image reading device 12, and the dynamics of the first CCD sensor 64 and the second CCD sensor 66. It is configured such that the total dynamic range after subtracting this overlapping area from the range (that is, the total dynamic range capable of obtaining the required S / N ratio) is not less than the dynamic range required for image reading. . Figure 3
FIG. 4 schematically shows the dynamic range of the first CCD sensor 64 and the second CCD sensor 66 in the image reading device 12 of the illustrated example, and FIG. 4 is a graph showing the relationship between the light intensity (light amount) of the transmitted light T before division and the CCD output. Are schematically shown respectively. Since the transmitted light T is divided into 45: 1 in the image reading device 12 as described above, the first C
The transmitted light T ₁ of 44/45 of the transmitted light T and the transmitted light T ₂ of 1/45 of the transmitted light T are input to the CD sensor 64 and the second CCD sensor 66.

The density area that can be recorded on a general negative film has a density of 0.1 to 3.2, and it is necessary to read this range with a density resolution of 0.01 in order to perform highly accurate image reading. is there. In other words, in order to read the entire density area that can be recorded on the negative film, it is necessary to read with a dynamic range of 62 dB or more and with a sufficient S / N ratio for density resolution of 0.01 dB. Should be read with an S / N ratio of 33 dB (in the analysis of the present inventor, the S / N ratio of 33 dB in general negative film image reading is a necessary and sufficient condition for outputting a high quality finished print). There is.

For example, the first CCD sensor 64 and the second CCD sensor 64
The total dynamic range of the CCD sensor 66 is 65
In the case of dB, as shown in FIG. 3, the dynamic range for obtaining the S / N ratio of 33 dB is 32 dB with one line CCD, and the dynamic range of 62 dB required for reading is secured. Can not do it.

On the other hand, in the image reading device 12 according to the present invention, as described above, the first CCD sensor 64 is used.
The second CCD sensor 66 is switched and used. Here, the first CCD sensor 64 and the second CCD sensor 6
The transmitted light T incident on 6 is split by the half mirror 62 at different light quantity ratios, and in the illustrated example, 45: 1 (20 l) corresponding to the required S / N ratio of 33 dB.
og45 = 33 dB). That is, FIG.
Further, as shown in FIG. 4, the portion corresponding to the lower limit 33 dB of the measurement light amount region of the second CCD sensor 66 is the first C
It overlaps with the measurement light amount region of the CD sensor 64,
At the time when the CD sensor 64 is saturated, the second CCD sensor 66 is in a state of rising by 33 dB corresponding to the S / N ratio.

Therefore, the first CCD sensor 64 is 33d
After reading 32 dB for which the S / N ratio of B is secured and saturating, the reading is switched to the second CCD sensor 66, and while the S / N ratio of 33 dB is secured, the second CCD sensor 66 causes a further 32 dB. Since it is possible to read minutes, it is possible to realize image reading of a dynamic range (corresponding to DL in FIG. 4) of 64 dB in total of 32 dB + 32 dB with an S / N ratio of 33 dB. Therefore, with the above configuration, highly accurate image reading with a required S / N ratio can be realized in a wide dynamic range, and the dynamics of the line CCD with respect to the required S / N ratio can be realized. The range can be used efficiently without waste.

In the illustrated example, the transmitted light T is divided into 45: 1 with the S / N ratio set to 33 dB, but the present invention is not limited to this, and it may be 3 depending on the required reading accuracy.
Various modes are possible corresponding to the S / N ratio of less than 3 dB or more than 33 d. Also, the line CCD to be used
If the dynamic range is narrow, the reading accuracy may decrease, but the S / N ratio may be reduced to secure the dynamic range, or if the dynamic range of the line CCD used is sufficiently wide, The S / N ratio may be set to be large and the dynamic range may be set to be narrow as much as possible to realize more accurate image reading. Further, if two line CCDs do not provide sufficient dynamic range, three or more line CCDs may be used.

Further, in the illustrated example, the same CCD sensor is used, and the transmitted light T is divided by the half mirrors 62 having different divided light amounts, so that the saturated light amounts of the two are made different, but the present invention is limited to this configuration. For example, as shown in FIG. 5, for R, G and B, a CCD sensor having two (plural) line CCDs of line CCDs 1 and 2 such as R ₁ and R ₂ ... The line CCDs 1 and 2 may have different saturated light amounts, or a normal line CCD controls each pixel by dividing it into even-numbered pixels and odd-numbered pixels. It may be changed to use as a plurality of CCD sensors. As means for varying the saturated light amount of each CCD sensor (photoelectric conversion element), a method of using an optical filter, a method of changing the accumulation time using an electronic shutter, in addition to the half mirrors having different spectral ratios in the illustrated example, A method of changing the clock rate to change the storage time is exemplified.

The switching timing of the CCD sensor is not limited to the time when the CCD sensor with a low saturated light amount is saturated, but may be before the saturation. However, as in the above-described example, the mode in which the CCD sensor with a low saturated light amount is switched to the point of saturation (or immediately before) is advantageous in terms of dynamic range, S / N ratio, and the like. Furthermore, CCD
In addition to switching and using the sensors, the image reading may be performed by weighting and adding the measurement results of the plurality of CCD sensors.

By the way, in an ordinary image reading apparatus, the light amount data read by the CCD sensor is amplified and then A / D changed and processed as an image signal. CCD
The light amount data read by the sensor is amplified and LO
After G conversion, A / D conversion is performed.

As described above, in order to obtain image information with high accuracy and output a high quality finished print, it is necessary to obtain image information with a density resolution of about 0.01. here,
For example, in order to read the density range 3.2 (which can be recorded) on a negative film with a resolution of 0.01, 10 ^3.2 ÷ (1-10 ^0.01 ) ≈ 68042, which is high performance of 17 bits or more and expensive. A / D converter is required, and a high-performance and expensive A / D converter with 13 bits or more is required even when the reading density range is set to 2.0 by prescan. Moreover, the A / D conversion also takes a very long time. for that reason,
In a conventional image reading apparatus, 16- to 18-bit A / D converters perform low-speed processing, or 8 to 12-bit A / D converters perform high-speed processing while degrading image quality.

On the other hand, in the image reading device 12 (digital photo printer 10) according to the second aspect of the present invention, the light amount data read by the first CCD sensor 64 and the second CCD sensor 66 and amplified by the amplifiers 22a and 22b. After LOG conversion, A / D
Convert. According to the present invention as described above, even when the density range 3.2 is read with a resolution of 0.01 as described above, 3.2 ÷ 0.01 = 320, so that A / D conversion is performed with 9 bits. Moreover, when the reading density range is set to 2.0, A / D conversion can be performed with 8 bits, so that inexpensive and small A / D converters 26a and 26b can be used for quick and high precision. Na A
The D / D conversion can be performed, and the cost of the image reading device 12 can be significantly reduced.

The digital image signal (image information) converted by the A / D converters 26a and 26b of the CCD processing unit 30 is then subjected to the first CCD by the CCD correction unit 32.
After correcting the error (variation in characteristics) of each pixel of the sensor 64 and the second CCD sensor 66, the dark attenuation and the variation in dark attenuation, the magnification conversion unit 36 performs magnification conversion and sharpness enhancement (unsharp mask). Then, it is transferred to the setup device 14.

Further, the input timing control section 35 receives the image reading start signal and sets the processing timing of the image information to the first CCD sensor 64 and the second CCD sensor 66.
A / D converters 26a and 26b, a CCD correction unit 32,
Further, the timing selector 88 of the setup device 14
Etc.

In the image reading apparatus 12 of the illustrated example, the line CCD is used as the photoelectric conversion element, but the present invention is not limited to this, and the area CCD can be suitably used, and other than the CCD. Any of various known photoelectric conversion elements such as a photomultiplier can be used.
In addition to the method of reading the image recorded on the film F by slit scanning, a flying spot scanner (FSS), a light beam scanning (so-called raster scanning) or the like may be used.

The setup device 14 is the image reading device 1.
The quality of the image information transferred from 2 is verified, color / gradation correction is performed if necessary, and transferred to the image forming apparatus 16 as image information for output (printing). In addition, a first selector 70, three frame memories (FM) 72a, 72b and 72c, a second selector 74, a setup calculation storage unit 76, and a color gradation correction display control unit 78 (hereinafter referred to as a display control unit 78). And)
Display 80, input means 82, and color correction unit 84
A tone correction unit 86, a timing selector 88, and an output timing control unit 90.

The image information from the magnification conversion section 36 is first transferred to the first selector 70. The first selector 70 outputs the image information of each frame of the film F to the three frame memories 7
2a, 72b and 72c are sequentially allocated. That is,
For example, the first selector 70 initially connects the transfer path so as to store the image information of the first frame in the frame memory 72a. When the storage in the frame memory 72a is completed, the first
The selector 70 switches the transfer path so that the image information of the second frame is stored in the frame memory 72b.

On the other hand, when the image information of the first frame is stored in the frame memory 72a, the second selector 74 connects the frame memory 72a, the setup calculation storage section 76 and the display control section 78. The setup calculation storage unit 76
The optimum image processing condition (setup condition) for this image is calculated according to the image information read from the frame memory 72a, and the display control unit 78 is controlled based on this result. The display control unit 78 includes the image information read from the frame memory 72a and the setup calculation storage unit 7
Based on the instruction signal from 6, the simulation image corresponding to the finished print under this condition is displayed on the display 80.

The operator checks the quality of the image displayed on the display 80 to check the quality. If the test is passed, the start key of the input means 82 is pressed. If the test is not passed, the correction key is pressed. The tone correction key is used to input an instruction for color and / or tone correction to the input means 82. The setup calculation storage unit 76 controls the display control unit 78 according to the input instruction for color and / or gradation correction, and the display control unit 78 displays the simulation image again on the display 80 according to this control. This operation is repeated until the quality inspection of the image displayed on the display 80 passes.

As a result of the above operation, when the quality test is passed and the start key of the input means 82 is pressed, the setup calculation storage unit 76 performs color correction of the color correction and gradation correction signals according to the set-up conditions that have been established. The data is transferred to the unit 84 and the gradation correction unit 86. At the same time, the second selector 74 connects the frame memory 72a and the color correction unit 84, and the image information read from the frame memory 72a is processed by the color correction unit 84 and the gradation correction unit 86 so that the color / color according to the setup condition is satisfied. Gradation correction is performed and the image is transferred to the image forming apparatus 16. Further, the second selector 74 simultaneously includes the frame memory 72b, the setup calculation storage unit 76, and the display control unit 78.
Are connected to each other, and the quality of the image stored in the frame memory 72b is similarly verified.

Outputs from various parts of the setup device 14, such as the setup calculation storage part 79, the display control part 78, the color correction part 84, and the gradation correction part 86, and the image forming apparatus 1
Outputs from the respective parts such as the D / A converter 92, the AOM driver 94 and the like arranged in FIG. 6 and the driving of the polygon mirror 96 are controlled by the output timing control section 90.

By the way, in the digital photo printer 10 as described above, depending on the purpose of the finished print such as a New Year's card, it is necessary to output a character to the finished print in addition to the image read from the film F, for example, by an external input. . Here, if a normal image (image), a relatively high-quality image can be obtained even at a resolution of about 300 dpi, but at least 40 characters are required when outputting characters.
If there is no resolution of about 0 dpi, preferably about 600 dpi, reproduced characters will be jagged and high-quality finished prints cannot be output. On the other hand, if the number of output pixels of image information is increased in order to improve the quality of characters, it is necessary to increase the capacity of the frame memory and the like accordingly, resulting in a significant increase in the cost of the device.

Therefore, in the digital photo printer 10 according to the third aspect of the present invention, the image information (image) read from the film F is a preferable aspect.
And a character frame memory for storing character information, the capacity of the character frame memory is larger than that of the image frame memory in the vertical and horizontal directions. Both have at least twice.

FIG. 6 shows an example of the structure of such a frame memory. In the illustrated example, the address from the reference clock is sent to the horizontal address counter 150. On the other hand,
The vertical address counter 152 counts the output from the horizontal address counter 150. As described above, in the digital photo printer 10, 35 mm film is read at 1100 (pixels) × 1700 (lines). Therefore, the address from the horizontal address counter 150 and the vertical address counter 152 is output as 12 bits, and the 12-bit address is sent to the character frame memory 154 as it is, while the R, G, and B image frame memories 156R, 156G, and 156B
, The 11-bit address is sent (counted), discarding the LSB at the bottom. Therefore, the resolution of the character frame memory 154 is doubled in both the vertical direction and the horizontal direction (that is, four times in total).

The R, G, and B image information stored in the image frame memories 156R, 156G, and 156B are converted into 8-bit image information (that is, 1100 × 1700 × 8bi) according to the 11-bit address.
t), selectors 158R and 158G corresponding to each
And 158B.

On the other hand, the character information stored in the character frame memory 154 is 4-bit character information (that is, 2200) in accordance with the above-mentioned 12-bit clock signal.
× 3400 × 4 bits), which is output to the table 160. Here, in the table 160, the color information Cr is sent from the CPU.
Is sent, and "2 ⁴ -1 = 15 colors" is selected from "(2 ⁸ ) ³ = 16777216" and used. The character information is output as 24 bits from the table 160 and is sent as 8 bits to each of the selectors 158R, 158G and 158B for each color. It should be noted that "-1" in the color selection indicates whether the image frame memory 156 or the character frame memory 154 is used by the selector 1
58 is used for outputting the selection signal i selected, and for example, when the 4-bit character information from the character frame memory 154 is all "0", the image information is selected, and otherwise the character information is selected. The selection signal i is output to the selector 158 by such a method.

Selectors 158R, 158G and 158
B selects image information or character information according to the selection signal i from the table 160 and outputs the image information or character information.

As described above, the image frame memory and the character frame memory for storing character information are separately provided, and the character frame memory has a capacity larger than that of the image frame memory in the vertical direction. By doubling at least twice in the horizontal direction, it is possible to output not only images but also high-quality finished prints in which high-quality characters are recorded, and at the same time, it is possible to achieve high image quality of characters with a minimum cost increase. Therefore, it is possible to inexpensively realize an image reading apparatus capable of outputting a high-quality image in which both characters and images are reproduced with a sufficient number of pixels without increasing the memory and simplifying the handling of clocks and addresses. it can. Furthermore, since the characters and images are handled in separate frame memories,
It is possible to easily change or correct characters.

In the above example, the character frame memory has twice the capacity in the vertical and horizontal directions as compared with the image frame memory, but the present invention is not limited to this. It may have a storage capacity of three times or more.

The set-up device 14 in the illustrated example has three frame memories 72a, 72b and 72c, but the number of frame memories is not limited to three, and one, two, or four or more frame memories are used. It may have a memory. Since the digital photo printer 10 of the illustrated example is basically composed of three devices, that is, the image reading device 12, the setup device 14, and the image forming device 16, the processing efficiency and the cost of the digital photo printer 10 are reduced. Considering this, it is considered that the number of frame memories is most balanced among the three in the illustrated example.

The image forming apparatus 16 is the setup apparatus 1
4, the photosensitive material A is scanned and exposed by light beam scanning in accordance with the image information transferred from 4, and the exposed photosensitive material A is developed and output as a finish print P. It has a converter 92, an AOM driver 94, an image exposure section 98, and a developing section 100.

The image information output from the setup device 14 is converted to analog image information by the D / A converter 92 and then transferred to the AOM driver 94.
The AOM driver 94 drives the acousto-optic modulator (AOM) 104 of the image exposure unit 98 so as to modulate the light beam according to the transferred image information.

On the other hand, the image exposure section 98 scans and exposes the photosensitive material A by light beam scanning (raster scan) to record the image of the image information on the photosensitive material A, and is conceptually shown in FIG. As described above, a light source 102R that emits a light beam in a narrow band wavelength region corresponding to the exposure of the R photosensitive layer formed on the photosensitive material A, a light source 102G that similarly corresponds to the exposure of the G photosensitive layer, and a B photosensitive layer. Light source of the light beam of the light source 102B corresponding to the exposure of A, and the light beam emitted from each light source are respectively modulated according to the recorded image A
It has OMs 104R, 104G and 104B, a polygon mirror 96 as an optical deflector, an fθ lens 106, and a sub-scanning conveying means 108 for the photosensitive material A.

Light source 102 (102R, 102G, 102)
Each of the light beams emitted from B) and traveling at different angles is associated with the corresponding AOM 104 (104).
R, 104G, 104B). The light source 10
Various light beam light sources capable of emitting a light beam of a predetermined wavelength corresponding to the photosensitive layer of the photosensitive material A can be used as 2, and various semiconductor lasers, LEDs, gas lasers such as He-Ne lasers, and the like can be used. It is illustrated. Further, it may be a multiplexing optical system that multiplexes the respective light beams. To each AOM 104, R, G, and B drive signals r, g, and b corresponding to the recorded image are transferred from the AOM driver 94, and the incident light beam is intensity-modulated according to the recorded image.

Each light beam modulated by the AOM 104 enters a polygon mirror 96 as an optical deflector, is reflected, and is deflected in the main scanning direction (arrow x direction in the figure).
Then, the photosensitive material A is adjusted by the fθ lens 104 so as to form an image with a predetermined beam shape at a predetermined scanning position z.
Incident on. The optical deflector may be not only the polygon mirror shown in the drawing but also a resonant scanner, a galvanometer mirror, or the like. In addition, such an image exposure unit 9
Needless to say, a light beam shaping means and a surface tilt correction optical system may be provided in the optical system 8.

On the other hand, the photosensitive material A is loaded in a predetermined position while being wound in a roll and shielded from light. Such a photosensitive material A is drawn out by a drawing-out means such as a drawing-out roller and cut into a predetermined length by a cutter (not shown), and then a pair of rollers 108a arranged across a scanning position z constituting the sub-scanning means 108. And 108b
While being held at the scanning position z, it is sub-scanned and conveyed in a sub-scanning direction (direction of arrow y in the figure) substantially orthogonal to the main scanning direction. Here, since the light beam is deflected in the main scanning direction as described above, the entire surface of the photosensitive material A conveyed in the sub scanning direction is two-dimensionally scanned by the light beam, and the photosensitive material A is set on the setup device 14. The image of the transferred image information is recorded.

The exposed photosensitive material A is then carried into the developing section 100 by the conveying roller pair 110 and subjected to a developing process to be a finished print P. Here, for example, when the photosensitive material A is a silver salt photographic photosensitive material, the developing unit 10
Reference numeral 0 is composed of a color developing / developing tank 112, a bleaching / fixing tank 114, washing tanks 116a, 116b and 116c, a drying section 118, etc. The photosensitive material A is subjected to a predetermined processing in each processing tank to obtain a finished print P. Is output.

In the illustrated example, the light beam is directed to the AOM10.
However, in addition to this, the light beam may be modulated according to the recorded image if the light source such as an LD is capable of direct modulation. In addition to the two pairs of rollers arranged with the scanning position sandwiched therebetween, the sub-scanning conveying means includes an exposure drum for holding the photosensitive material at the scanning position and two nip rollers arranged with the scanning position sandwiched therebetween. Good.

Further, in addition to the scanning of the light beam in the illustrated example,
It may be a so-called drum scanner in which a photosensitive material is wound around a drum, a light beam is incident on one point, and the drum is rotated and moved in the axial direction. In addition to the light beam scanning, surface exposure using a surface light source and a liquid crystal shutter may be used, or exposure using a linear light source such as an LED array may be used. It is also possible to output an image to a display such as.

In the above description, the first, second and third aspects of the image reading apparatus of the present invention are applied to a digital photo printer for reading and outputting an image of a transparent original such as a negative or reversal film. However, it goes without saying that the present invention can be suitably used for reading an image of a reflective original in addition to this.

Although the image reading apparatus of the present invention has been described above in detail, the present invention is not limited to the above-described embodiments, and various improvements and changes may be made without departing from the gist of the present invention. Of course.

[0087]

As described above in detail, according to the first aspect of the image reading apparatus of the present invention, it is possible to widen the dynamic range of image reading, and to perform one-time scanning without prescanning. The entire image density area that can be recorded on film etc. by image reading can be read with high spatial resolution and high density resolution, greatly simplifying the configuration and operation of the image reading device and realizing an inexpensive image reading device. can do. Further, according to the second aspect of the image reading apparatus of the present invention, a high-performance A / D converter such as 16 bits is not required, and an inexpensive A / D converter with high speed and high accuracy can be used.
Since / D conversion may be performed, the cost of the image reading apparatus can be reduced. Further, according to the third aspect of the image reading apparatus of the present invention, not only an image but also a high-quality finished print in which high-quality characters are recorded can be output, and the high image quality of the characters can be obtained at a minimum cost. It is possible to realize an image reading apparatus that can be realized by a close-up and output a high-quality image at a low cost, and it is also possible to easily correct or rewrite characters.

[Brief description of drawings]

FIG. 1 is a first, second and third image reading apparatus of the present invention.
It is a figure which shows notionally an example of the digital photo printer using the aspect of FIG.

FIG. 2 is a perspective view conceptually showing a part of the image reading device of the digital photo printer shown in FIG.

FIG. 3 is a diagram conceptually showing a usage state of a CCD sensor in the image reading apparatus of the digital photo printer shown in FIG.

FIG. 4 is a graph conceptually showing a usage state of a CCD sensor in the image reading apparatus of the digital photo printer shown in FIG.

FIG. 5 is a diagram conceptually showing an example of a CCD sensor used in the first aspect of the image reading apparatus of the present invention.

FIG. 6 is a diagram showing an example of a configuration of a memory used in a third aspect of the image reading apparatus of the present invention.

7 is a schematic perspective view conceptually showing a part of the image forming apparatus of the digital photo printer shown in FIG.

[Explanation of symbols]

10 Digital Photo Printer 12 Image Reading Device 14 Setup Device 16 Image Forming Device 18 Image Reading Unit 20a, 20b Correlated Double Sampling (CDS) 22a, 22b Amplifier 24a, 24b LOG Converter 26a, 26b A / D Converter 28 Selector 30 CCD control unit 32 CCD correction unit 34 Density conversion unit 35 Input timing control unit 36 Magnification conversion unit 50 Light source 52 Filter unit 54 Condensing unit 56 Conveying roller pair 60 Imaging lens 62 Half mirror 64 First CCD sensor 66 Second CCD sensor 70th 1 selector 72a, 72b, 72c frame memory 74 second selector 76 setup calculation storage section 78 color gradation correction display control section 80 display 82 input means 84 color correction section 86 gradation correction section 88 timing selector 90 output Force timing control unit 92 D / A converter 94 AON driver 96 Polygon mirror 98 Image exposure unit 100 Developing unit 102 (102R, 102G, 102B) Light source 104 (104R, 104G, 104B) Acousto-optic modulator (AOM) 106 fθ lens 108 Sub-scanning means 112 Coloring / developing tank 114 Bleaching / fixing tank 116a, 116b, 116c Washing tank 118 Drying section 150 Horizontal address counter 152 Vertical address counter 154 Character frame memory 156 (156R, 156G, 156B) Image frame memory 158 (158R, 158R, 158G, 158B) Selector 160 Table A Photosensitive material P Finish print

Claims (4)

[Claims] 1. An image reading device for reading an image carried by the original by photoelectrically converting the reflected light from the original or the transmitted light of the original to read, and a plurality of photoelectric conversion elements having different limits of measurement light quantity. An image reading apparatus comprising: a unit for selecting the photoelectric conversion element according to the amount of light to be measured or a unit for adding the measurement results of the photoelectric conversion elements. 2. A photoelectric conversion element having a low measurement light amount limit, at least an upper limit portion of a measurement light amount region of the photoelectric conversion element, and a photoelectric conversion element having a high measurement light amount limit, a lower limit portion of the measurement light amount region, and the overlapped measurement light amount region. Is an amount corresponding to at least the required S / N ratio, and the total obtained by subtracting the S / N ratio from the dynamic range of each photoelectric conversion element is wider than the dynamic range required for image reading. The image reading apparatus according to claim 1. 3. An image reading device for photoelectrically converting reflected light from a document or transmitted light of the document to read an image carried by the document, performing signal processing and outputting as image information, the image being read by photoelectric conversion. An image reading apparatus characterized by subjecting the obtained light quantity data to LOG conversion and then A / D conversion. 4. An image reading apparatus for photoelectrically converting reflected light from a manuscript or transmitted light of a manuscript to read an image carried by the manuscript, performing signal processing and outputting as image information, the image information being temporarily stored. And a character frame memory for temporarily storing character information, and the character frame memory has a resolution with respect to the image frame memory in both the vertical and horizontal directions of the image information. An image reading apparatus having at least two times the number.