JP3312787B2 - Image processing system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing system, such as a copier, provided with an image reading means for reading an original by reflecting light from a light source, and in particular, the size of the original is smaller than the size of the recording paper. The present invention relates to an image processing system capable of removing a black image portion around a document image formed on a recording sheet in some cases.

[0002]

2. Description of the Related Art When copying, there is no problem as long as the paper size of the original and the size of the recording paper match, but for example, a book is placed on a contact glass and the pressure plate is opened, or the pressure plate is closed. However, if the copy is performed while keeping the unevenness of the book as it is, the periphery of the recorded original image often becomes black as shown in FIG. This is because, as shown in FIG. 5, in the image reading means, light emitted from the light source 803 does not reflect on the surface of the document 804 around the document 804 placed on the contact glass 801 and there is no reflection from the pressure plate. Naturally, light does not enter the imaging device or the photosensitive drum. That is, as is apparent from the figure, the light ray a is reflected on the document surface, and the reflected light is incident on an image pickup device (not shown) or the like. Therefore, the signal of the light amount corresponding to the image on the document surface is used as the input signal. Can be obtained, ray b
Travels farther without reflection, the input signal becomes 0, and therefore becomes black data. For this reason, a document having a large unevenness such as a book is covered with white paper or the like, and a pressure plate 802 is placed over the document as needed to perform copying.

[0003]

However, when copying a book or the like, it is troublesome to insert white paper between the pressure plate 802 and the document, and the document may be displaced when the pressure plate is put on the platen. Even if it is held down, copying is performed with the central part of the book raised. Therefore, the operator does not actually use the pressure plate and the operator presses the original by hand to make a copy,
The surrounding black image was unavoidable.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image processing system which solves the problem of copying an original having large irregularities as described above, and in which a black image is not recorded around the output original image without using a pressure plate. It is intended to provide.

[0005]

In order to achieve this object,
According to the present invention, in an image processing system including an image reading unit that reads an original by reflecting light from a light source and an image forming unit that forms an image based on the read image data, an edge is formed by the image reading unit. Is a straight line
For each line data read from the original, black data from the first pixel data of the line to immediately before white data continuous for a predetermined number or more, and black data next to white data continuous for a predetermined number or more appearing at the end of the line. A sequence of pixel numbers at a boundary between an area to be converted to white data and an area not to be converted so that the data to the last pixel are converted to white data.
Judgment of outlier pixels based on the tolerance of the arithmetic progression
To, it was configured to Fix <br/> positive as the abnormal value sequence is substantially an arithmetic progression, including the display device, prior to the image formation on the recording sheet, the rectangular document on the display device By displaying the whole image, the coordinates of the four vertices of the rectangle are detected, and one of two different start point calculation formulas is determined using a point corresponding to a point on two sides of the rectangle displaying the whole image of the document as a start point. The start point of each line is calculated using the two points on the other two sides of the rectangle as the end point, and the end point of each line is calculated using one of two different end point calculation formulas. That the start point calculation formula and the end point calculation formula are configured to include the tolerance of the arithmetic progression, the tolerances of the respective calculation formulas are calculated in advance, and at the time of image transfer for image formation, Use the tolerance to calculate the start and end points. It is characterized in the thing.

[0006]

In the one-line data read by the image reading means, from the first pixel data to the black data immediately preceding the white data continuous for a predetermined number or more, and the white data continuous for a predetermined number or more that appeared last. Since the configuration from the next black data to the last pixel is converted into white data, the black data around the document is converted into white data.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram mainly showing a control unit of an image input device 1 and an image output device 2 of an image processing system according to the present invention. FIG. 1A is a block diagram of the image input device 1, in which 11 is an image reading unit.
The imaging device 112 reads an image and outputs an analog signal, and the AD converter 116 converts it into digital image data. The digital image data is input to the image output device 2 via the shading correction circuit 117, the sampling position shift correction circuit 118, and the basic image processing means 12.
The basic image processing means 12 includes various image processing modules and performs various image processing. Further, if necessary, image processing by the extended image processing means 13 is also performed.

FIG. 1B is a block diagram mainly showing a control system of the image output apparatus 2. In the figure, reference numeral 23 denotes a recording control circuit, and reference numeral 21 denotes an image forming means. The image forming unit 21 is of an electrophotographic type, and includes a photosensitive drum, a latent image forming unit,
A developing unit, a transfer unit and the like are provided. The imaging device 112
Converts the incident signal due to the reflected light into an analog electric signal corresponding to each pixel for each line and outputs the analog electric signal. The digitized image data is binarized by a binarization circuit 121 of the basic image processing means 12 into 'black' (hereinafter referred to as '0') or 'white' (hereinafter referred to as '1'). You. For example,
When the image as shown in FIG. 4 is read, if there is no noise, the output of the binarization circuit 121 is that the first few lines are all one line and all the pixel data are "0".
It is. When it reaches the upper end of the document, "1" appears in one line. If the original is tilted and the right side is up, for example, “1” appears at a position near the end of one line data, and if the left side is up, “1” is at a position near the beginning of one line data. Appear. When the document is further advanced, the upper end of the document becomes all white, and the left and right become black. That is, the first area of one line data is “0”, the subsequent area is “1”, and the last area is “0”. When the character portion or the image portion of the document is reached, the first area of the one-line data is "0", followed by "1" for several pixels, and thereafter "1".
The area of area “0” is repeated, and the last area is “0” after the area of “1” at the end (right end of the document). The lower end of the document is similar to the upper end.

However, the above does not actually occur due to noise. '1' due to noise also appears in the upper, lower, left and right black areas of the document. Therefore, in order not to judge this “1” as an image inside the document, when judging “1” or “0” in order from the first pixel of one line, a predetermined number or more of “1” continues. If not, it is not determined that the document is inside. However, once it is determined that the image is inside the document, it is determined that the image is inside the document even if “1” continues for less than a predetermined number. Similarly, in the area at the end of one line, after the predetermined number or more of “1” s continue, if the area of “1” does not appear continuously for the predetermined number or more until the end of one line, the predetermined number of “1” or more It is determined that the last pixel of the white area where 1 'is continuous is inside the document. When the document is tilted, the area may be determined to be less than the predetermined number of '1' areas at the four corners even though the document is inside, and may be determined to be outside the document, but this poses a practical problem. No. As described above, if all the data in the area determined to be outside the document is replaced with “1”, then the image data is sent to the image output device 2, and all the portions determined to be outside the document are set as white areas. An image is formed.
Therefore, all the upper, lower, left and right black frames in FIG. 4 are converted to white and copied.

FIG. 2 is a diagram showing an embodiment of a circuit of an apparatus for realizing the above algorithm. Pixel counter 12 in FIG.
2. The white counter 123, the latches 126 and 128, and the flip-flop 127 are reset by a reset signal (not shown) before reading the pixel data of one line.
In the predetermined number register 124, the maximum continuous number of possible "1" s in the document area is set in advance by a CPU (not shown).

When the reading of one line of pixel data starts in synchronization with the pixel clock a, the output of the binarization circuit 121 outputs "1" if the input pixel data is "white" (a value equal to or more than a predetermined value). 'Appears, otherwise' 1 'or' 0 'appears (eg, the output toggles on the trailing edge of the pixel clock). The pixel counter 122 starts counting and is incremented by one each time a pixel clock is input. When "1" appears at the output of the binarization circuit 121 regardless of whether noise occurs or not, the white counter 123 is counted up by the next pixel clock. However, when "0" appears in the output of the binarization circuit 121, the white counter 123 is reset. Binarization circuit 121
When the number of '1's reaching the predetermined number appears continuously in the output, the value of the white counter 123 matches the value of the predetermined number register 124, and the output of the comparator 125 becomes'1'. The value α1 of the pixel counter is latched by the latch 126 and read by the CPU. The CPU calculates “α2 = α1−predetermined number”. Α2 is the pixel number immediately before the document area.

The flip-flop 127 is set when the coincidence signal is output from the comparator 125 as described above. Since the flip-flop 127 remains set while reading the line thereafter, the flip-flop 127 is output after the coincidence signal is output (that is, (After entering the document area), the value of the pixel counter at that time is set in the latch 128 each time the 'black' data appears in the output of the binarization circuit 121. The latch 128 is reset by the output of the comparator 125 when a predetermined number or more of continuous white appears. When the comparator 125 does not output a match signal and completes reading of one line while the pixel counter value is set, the latch 128 is reset. Β1 set in the latch 128 is the pixel number immediately after the document area.

In order to replace the data outside the original area with '1' using α2 and β1 indicating the original area, α2, β
It is necessary to temporarily store the output data of the binarization circuit 121 used for determining 1. The one-line buffer 129 shown in FIG. 2 plays this role. That is,
The timing is delayed by one line, and the selector 135 replaces the data outside the document area with “1”. The JK flip-flop 134 indicates the period in the document area. When the Q output is "1", the output of the one-line buffer 129 is selected as the output D of the selector 135, and the Q output of the JK flip-flop 134 is "0". At the time, that is, outside the manuscript area, + 5V input is selected and replaced with '1'.

When the value of the pixel counter 122 becomes α2, that is, the pixel number immediately before the original area, the JK flip-flop 134 outputs a coincidence signal from the comparator 132 and is set at the leading edge of the next pixel clock. You. Register 130
, 131 are set by the CPU (not shown), respectively, where (β2 = β
1-1). That is, β2 is the last pixel number of the document area. When the pixel counter 122 becomes β2, a match signal is output from the comparator 133, and the JK flip-flop 134 is reset at the leading edge of the next pixel clock. selector
The output signal of 135 is transferred to the image output device 2.

If noise enters the leading edge and trailing edge of the document area, the above α2 and β2 may deviate from the true values by several pixels. This shift can be corrected as follows. One method focuses on the fact that both the leading edge and the trailing edge of the document area are straight lines, and sets α2 · 1, α2 · 2,... Α2 · n of several consecutive lines and set β2 of β2.
... Β2 · n each form an arithmetic progression. Therefore, for example, five sequences of α2 are 80, 83, 85, 9
If it were 0,90, the fourth value 90 is obviously not the true value. Therefore, this was judged to be due to noise, and 90
To 88 (or 87). In order to realize the above correction, the one-line buffer 129 shown in FIG. 2 is replaced with, for example, a five-line buffer, and the above-mentioned α2 for five lines is compared. After acquiring α2 and β2 for five consecutive lines, the CPU obtains a tolerance of the arithmetic progression and corrects an abnormal value. In the above example, the differences are 3, 2, 5, and 0, respectively, and 5,0 is determined to be abnormal, and the fourth data is corrected.

Some originals P have a black mark M or the like at the end as shown in FIG. Assuming a pixel density of 16 lines / mm, even a 10 mm long mark is 160
In this case, a buffer of about 500 to 1000 lines is required to find the true boundary. That is, for example, regarding the trailing edge of the document area,
The boundary pixel number is monitored over 500 to 1000 lines. Even if a certain range is B1, the other range is B2, and B2> B
If 1, B2 is adopted. A display device is added to the image input device 1, or a control processing device having a display device in addition to the image input device 1 and the image output device 2 is added, and the image of the document loaded at a predetermined position of the image input device is deleted. By reading and displaying the entire image of the document on the display device, a document area can be designated on the screen. This is a method of designating two points forming a diagonal of a displayed rectangle known by the image editing means, or a method of designating four vertices of the rectangle. However, in the former case, if the original is skewed, a black image around the original remains (if a little inside of the original is specified, it will not remain depending on the degree of inclination). Also,
At this time, if the resolution of the display device is low, the display device can be made inexpensive. That is, if the resolution is reduced in this manner, the capacity of the image buffer can be reduced, and there is no problem because the display purpose is not for reading characters or the like but for recognizing the outline of the document.

Hereinafter, the present invention will be described by taking the case of designating four points as an example. FIG. 6 is a diagram in which a document 341 is displayed on the screen 34. The above four points are the four vertices A, B,
C and D are meant. For specifying these four points, for example, a pointing device such as a mouse is used, and the line number 1 and the pixel number n of the four points are detected by a known technique.
At this time, the true line number (in the image input device) is kl and the pixel number is kn (k = resolution of the image input device / resolution of the display device). Therefore, the starting pixel numbers of the document in the image input device are line numbers klA to klC (k
IA and kIC are represented by knA + (knC-knA) N / (kIC-kIA) in the line numbers of points A and C, respectively (N is an integer that increases by one for each line with the line at point A being 0). Similarly, we calculate the C-D between the starting point pixel number for each line of, A-B and end pixel number of each line between B-D (decimal point Type 4 Discard 5 is an integer) .

Although the above description has been made on the case where the document is tilted downward to the right, the calculation can be similarly performed for the case where the original is tilted to the upper right. In the above, (knC-knA) / (klC-kIA) is the tolerance of the arithmetic progression, and knA is the first number of the progression. That is, the above calculation method relies on the fact that the sequence of the start point and the sequence of the end point of each continuous line of the rectangular document area form an arithmetic progression as described above. Since the above-mentioned tolerance d can be calculated before image reading for image data transfer to the image output device 2, multiplication d × N = e and addition knA + e are performed once per line at the time of image data transfer. Since the start point is obtained by performing the calculation once and the multiplication and the addition are performed once to obtain the end point, the calculation can be performed in a short time and the time can be sufficiently obtained.

The circuit for realizing the above method may be the same as the circuit within the dotted line shown in FIG. The CPU (not shown)
The coordinates (n, l) of four points are obtained in advance, the line numbers and pixel numbers (kn, kl) of the four points are calculated, and the four tolerances corresponding to the four sides forming the rectangle are calculated. When a line including a vertex (A in the example of FIG. 6) is reached at the time of image reading, α2 is calculated using one of the two equations for finding the starting point, set in the register 130, and the two equations for finding the ending point. Is calculated using one of the two, and is set in the register 131. In the example of FIG. 6, when the line including the point B is reached, the equation for finding the end point is switched to the other equation. When the line including the point C is reached, the equation for finding the start point is switched to the other equation. Then, .alpha.2 is set to a value exceeding the number of pixels in one line, and the selector 135 always selects the "1" input (+ 5v input) (the same applies until the point A is reached). FIG. 7 is a flowchart illustrating the processing procedure described above. In the figure, (a) is a processing flow before image reading for transferring image data to the image output device 2, and (b) is a processing flow at the time of transferring image data to the image output device 2. Since the details of the flowchart are as described above, the description is omitted.

In this system, the inclination of the original is corrected by the original image displayed on the display device having the coarse resolution.
In addition, it is possible to check whether the original is placed in a normal orientation and a normal position, and whether enlargement and reduction are appropriate. This check is performed by pressing a document display button on the operation unit. The display unit acquires the selected paper feed tray identification information of the image output device, and displays the outer shape of the recording paper on the display screen in the set direction. The recording paper and the original are displayed in the same manner as when the image of the original is recorded on the recording paper.

[0021]

As described above, according to the present invention,
Of the one-line data read by the image reading means, from the first pixel data to the black data immediately before the predetermined number or more of continuous white data, and next to the last and the predetermined number or more of continuous white data. By converting the black data around the original into white data by converting the black data to the last pixel into white data, even when the pressure plate is not used, the image around the output original image is No black image is recorded.

[Brief description of the drawings]

FIGS. 1A and 1B are functional block diagrams showing an embodiment of an image processing system according to the present invention.

FIG. 2 is a main part circuit diagram of the embodiment shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of a document used in the image processing system of the present invention.

FIG. 4 is a diagram showing an example of a conventional copy image.

FIG. 5 is a diagram illustrating copying in a state where a pressure plate cannot be used.

FIG. 6 is a diagram for explaining the present invention, and is a diagram for explaining a case where a document is inclined.

FIGS. 7 (a) and 7 (b) are flowcharts showing an embodiment of a processing procedure performed according to the present invention.

[Explanation of symbols]

1 ... image input device, 2 ... image output device, 11 ... image reading means, 12 ... basic image processing means, 13 ... extended image processing means, 21 ... image forming means, 23 ... recording control circuit, 34 ... screen,
112: imaging device, 116: AD converter, 117: shading correction circuit, 118: sampling position shift compensation circuit, 121: binarization circuit, 122: pixel counter, 123: white counter, 124: predetermined number register, 125 ... Comparator, 129 ... 1 line buffer, 132, 133 ... Comparator, 135 ... selector.

Continuation of the front page (56) References JP-A-62-144462 (JP, A) JP-A-2-264566 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 1 / 38-1/393 H04N 1/04-1/207

Claims (4)

(57) [Claims] And 1. A image reading means for reading an original by reflecting light from a light source, an image processing system including an image forming means for forming an image based on the image data read, the edges by the image reading means The part is straight
For each line data read from a certain document, from the first pixel data of the line to the black data immediately before a predetermined number or more of continuous white data and the next to the predetermined number or more of continuous white data appearing at the end of the line The process from the black data to the last pixel is converted into white data, and a pixel having an abnormal value is determined based on a tolerance of an arithmetic progression in a sequence of pixel numbers at a boundary between a region to be converted to white data and a region not to be converted .
Unishi, as the abnormal value sequence is substantially an arithmetic progression
The image processing system being characterized in that the arrangement of positive Fix. 2. The method according to claim 1, further comprising the step of: displaying a whole image of the rectangular document on the display device prior to forming an image on recording paper, thereby detecting coordinates of four vertexes of the rectangle. To display the entire image of the original
Starting from the point corresponding to the point on the two sides of the shape, two different
Starting point of each line using one of the starting point formulas
Is calculated, and a point on the other two sides of the rectangle is set as an end point.
Using one of two different endpoint calculations,
An image processing system characterized in that an end point of an in is calculated. 3. The image processing system according to claim 2, wherein the start point calculation formula and the end point calculation formula include a tolerance of an arithmetic progression. 4. A method according to claim 3, wherein the tolerances of the respective formulas are calculated in advance, and the starting point and the ending point are calculated by using the tolerances for each line when transferring an image for image formation. An image processing system characterized in that: