JPH10293842A - Image correcting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a corrected image of high quality by adjusting a relative shift in image data output position between the corrected image and uncorrected image. SOLUTION: This device converts image data written in respective line buffer memories 1-1 to 1-5 by multi-valued and binary image conversion parts 2-1 to 2-5 and is equipped with a buffer memory 3a which temporarily holds the binary image data in a bit map form; and the shape of the edge part of the image is recognized based on the image data, corrected image data D2 are outputted after a correcting process if there are pixels that need to be corrected, and for pixels which need not be corrected, image data D3 other than the corrected image data are outputted as they are. The output timing of the image data D3 other than the corrected data is delayed so that no time difference is generated between the time up to the output of the corrected image data D2 and the time up to the above image data D3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image correction apparatus provided in a digital image forming apparatus such as a laser printer, an LED printer, a digital copying machine, a facsimile machine, or a multifunction machine having a printer function, a copying function, a facsimile function and the like. More particularly, the present invention relates to an image correction apparatus having a function of correcting a data output position shift caused by an image correction process.

[0002]

2. Description of the Related Art A digital image forming apparatus such as a laser printer performs smooth image edge processing when performing image forming processing based on multi-valued input image data sent from a host computer or an image scanner. Some image processing apparatuses include an image correction device that performs edge smoothing correction for expression. In this type of image correction device,
Detection of density gradation information of input image data is combined with edge detection and correction using binary image data, and a high-quality image output is obtained by reflecting the correction data on the input image data. FIG. 5 is a block diagram showing a configuration of a conventional image correction device. As shown
The conventional image correction apparatus includes a plurality of line buffer memories 11-1 to 11 which temporarily store data for several lines of an input image in order to develop and detect multi-valued input image data D1 in a bitmap form. -5, and multi-level / binary image conversion units 12-1 to 12-5 for converting the multi-level image data written in the line buffer memories 11-1 to 11-5 into binary image data, respectively. An image development area (RAM) in which a large number of storage elements are arranged in a matrix corresponding to each dot position of input image data so that the converted binary image data is developed in a bitmap form and temporarily stored. 1
3a, and a target pixel P of image data developed on the image development area 13a of the image detection unit 13
A controller (not shown) that detects the positional relationship between surrounding pixels with respect to the image, an image correction unit 14 that generates correction data for a target pixel from position information of image data, and a pixel that has been subjected to image correction An image selection unit 15 that performs a selection process of outputting the corrected image data D2 from the image correction unit 14 and the multi-valued input image data (non-correction target image data) D3 for pixels for which image correction has not been performed; It has.

In this image correction apparatus, several lines of input image data sent from a computer, an image scanner, or the like are written into line buffer memories 11-1 to 11-5. The image data is converted into binary image data according to the density by the multi-value / binary image conversion units 12-1 to 12-5. The binary image data obtained by the conversion is sent to the image detection unit 13 and is expanded on the image expansion area 13a into a bitmap image corresponding to the dot pattern of the input image. Then, the positional relationship between the surrounding pixels and the target pixel P on the image development area 13a is detected, and the obtained positional information is sent to the image correcting unit 15. The image correction unit 15
The corrected image data D <b> 2 for the target pixel P is generated based on the input position information, and is output to the image selection unit 15.
For the line including the target pixel P, the pixel data is input to the image selection unit 15 as multi-value data other than the data path for performing the image correction. Then, the corrected image data D2 from the image correction unit 14 is output as it is for the pixels for which the image correction has been performed, and the non-correction target image data D3 is output as the output image data for the pixels for which the image correction has not been performed. Since the above series of image processing needs to be performed at the timing of image output, it is performed in synchronization with the common image processing reference clock CK.

[0004]

However, in the conventional image correction apparatus, the multi-value / binary image converters 12-1 to 12- are used.
5, since the processes in the image detecting unit 13 and the image correcting unit 14 are performed in synchronization with the common image processing reference clock CK, the image correcting process is not performed by the number of clocks for the time required for the processing in each unit. The output timing of the corrected image data D2 is delayed with respect to the non-correction target pixel data D3 input to the image selection unit 15 as multi-value data. As a result, a shift in the output timing between the corrected image data D2 and the non-correction pixel data D3 appears as a shift in the print output position, and as shown in FIG. There is a problem that the output positions of the pixels that do not match do not match. The problem to be solved by the present invention is to solve the above-mentioned disadvantages of the conventional technology, and to move the output position of the normal image which is not to be corrected in accordance with the processing time of the edge smoothing correction, so that the pixel to be corrected and the pixel to be corrected It is an object of the present invention to provide an image correction apparatus capable of adjusting a shift of an image output position of a pixel and outputting a higher-quality corrected image.

[0005]

According to an aspect of the present invention, there is provided an image processing apparatus comprising: a plurality of line buffer memories for temporarily storing data for several lines of input image data; A multi-valued-to-binary image conversion unit for converting multi-valued image data written in the buffer memory into binary image data, and an image for temporarily storing the converted binary image data developed in a bitmap form A developing unit for recognizing a shape of an edge portion of the image based on the image data developed in the image developing unit, and correcting the image data of the pixel if any pixel needs correction based on the result. An image correction device that performs processing and outputs image data after the correction processing, and outputs original image data in the case of a pixel that is not subjected to the correction processing. The output of the image data of the pixel not subjected to the correction processing is performed so that there is no time difference between the time until the image data of the pixel is output and the time until the image data of the pixel not subjected to the correction processing is output. It is characterized by having an image data shift unit for changing the timing. According to the device configuration of the first aspect of the present invention, the image data of the pixel not subjected to the correction processing is temporarily stored in the image data shift unit for the time required for the correction processing of the image data of the pixel requiring the correction. By performing the process of delaying the output timing by performing the process, it is possible to eliminate a shift between the image output positions of the correction target pixel and the non-correction target pixel, and to perform high-quality image output. In the invention according to claim 2,
2. The image correction device according to claim 1, wherein the line buffer memory for temporarily storing image data after a line including a pixel requiring correction among the plurality of line buffer memories stores the input image data at a lower level. It is characterized in that it is configured to be converted into gradation image data (for example, binary image data) and input. According to the apparatus configuration of the second aspect of the present invention, the capacity of the line buffer memory for temporarily storing the input image data of the line that does not need to be corrected can be reduced.

[0006]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing an example of an embodiment of an image correction device according to the present invention. As shown
The image correction apparatus 100 temporarily stores data for several lines of the input image in order to develop and detect the multi-valued input image data D1 in a bitmap form (5 in this example).
Line buffer memories 1-1 to 1-5).
Multi-level / binary image conversion units 2-1 to 2-5 for converting the multi-level image data written in each of the line buffer memories 1-1 to 1-5 into binary image data, respectively; An image having an image development area (RAM) 3a in which a large number of storage elements are arranged in a matrix corresponding to each dot position of input image data so that binary image data is developed in a bitmap form and temporarily stored. Detecting unit 3 and image detecting unit 3
The boundary (edge) between the black pixel region and the white pixel region is detected by detecting the position of the black pixel with respect to the pixel of interest P based on the image data developed on the image development region 3a.
And a controller (not shown) for recognizing the shape of the image data.
This is referred to as corrected image data. ) The image correction unit 4 generated as D2, the correction data from the image correction unit 4 for the pixels that have been subjected to the correction processing, and the multi-valued input image data (hereinafter, not to be corrected) for the pixels that have not been subjected to the image correction. Image selection unit 5 for selecting to output D3 as it is, time from input image data D1 being input to output of corrected image data D2, and output of image data D3 not to be corrected. And an image data shift unit 6 having a buffer memory 6a for changing the output timing of the image data D3 of the pixel that is not subjected to the correction processing so that no time difference occurs between the image data shift unit 6 and the image data D3.

FIG. 2A shows a multi-level / binary image converter 2-1.
It is a block diagram which shows the structure of 2-5. The multi-value / binary image conversion units 2-1 to 2-5 store the multi-value data serving as a reference in the comparison reference data storage unit 7, and the multi-value input image data D1 and the comparison reference data storage unit 7. A data comparing unit 8 that compares the stored multi-valued data with the stored multi-valued data and generates binary output data of “1” or “0” according to a table shown in FIG. The gradation of the data D1 is detected, and the input image data is replaced with binary data based on a certain density.

Next, the operation of the image correction apparatus according to the present embodiment will be described. When print data is sent from a computer, an image scanner, or the like, input image data for several lines is written to the line buffer memories 1-1 to 1-5 and written to the line buffer memories 1-1 to 1-5. Image data is converted to multi-level / binary image conversion units 2-1 to 2-1
In 2-5, the image data is converted into binary image data according to the density.
The binary image data obtained by the conversion is sent to the image detection unit 3 and is developed into a bitmap image corresponding to the dot pattern of the input image on the development area 3a. Then, it is detected how the surrounding pixels are located relative to the target pixel P on the development area 3a, and the obtained position information is sent to the image correction unit 4. The image correction unit 4 generates correction data for the target pixel P based on the input position information, and outputs the generated correction data to the image selection unit 5. For the line including the target pixel P, the image data of the pixels other than the image data of the target pixel P is input to the image selection unit 5 via the image data shift unit 6 without changing the multi-value data. Then, the corrected image data D2 from the image correcting unit 4 is output as the output image data for the pixel for which the image correction has been performed, and the non-correction image data D3 for the pixel for which the image correction has not been performed. Since the above series of image processing needs to be performed at the timing of image output, it is performed in synchronization with the common image processing reference clock CK.

For this reason, in the conventional image correction apparatus, the number of clocks for the time required for processing in the multi-value / binary image conversion units 2-1 to 2-5, the image detection unit 3, and the image correction unit 4 is calculated. The output timing of the corrected image data D2 is delayed with respect to the non-correction target image data D3,
As shown in FIG. 6, there is a problem that the output positions of the corrected image data D2 and the non-correction target image data D3 do not match. On the other hand, in the image correction apparatus 100 of the present embodiment, the line buffer memories 1-1 to 1--1
5, the image data shift unit 6 is provided in the middle of the line for guiding the non-correction target image data D3 to the image selection unit 5, so that the input image data D1 is input and the corrected image data D2 is output. The non-correction target image data D3 is temporarily stored in the image data shift unit 6 for the time required for the correction processing so that a time difference does not occur between the time and the time until the non-correction target image data D3 is output. Then, a process of delaying the output timing can be performed. By this delay processing, as shown in FIG. 3, it is possible to eliminate the displacement between the output positions of the corrected image data and the non-correction target image data, and to perform image output with the positional relationship of the pixels that match the input image.

Next, another embodiment of the present invention will be described. The image correction apparatus 100 shown in FIG. 1 includes line buffer memories 1-1 to 1-5 for the number of lines of the pixel matrix in the development area 3a of the image detection unit 3. However, it is necessary to hold the multi-valued input image data up to the line including the pixel of interest P, and the line buffer memories 1-4 and 1-5 for temporarily storing the image data of the subsequent lines are: It is sufficient to pass binary image data to the image detection unit 3. Therefore, in the image correction apparatus according to another embodiment of the present invention shown in FIG. 4, input image data after a line including a pixel of interest P is previously converted into binary image data as line buffer memories 1-4 ', 1'. -5 '
Is configured to be input. Thereby, the capacity of the line buffer memories 1-4 'and 1-5' can be reduced. For example, if the input image data D1 has an information amount of 8 bits per dot, the line buffer memories 1-4 ', 1-
5 'requires only 1/8 of the capacity. Also, in this case,
Since the image data converted into binary by the binary converter 2-3 is configured to be input to the line buffer memories 1-4 'and 1-5', it is not necessary to add a special circuit. Therefore, when the circuits of the line buffer memory unit and the multi-value / two-value conversion unit are configured by devices such as a gate array, the circuit scale is reduced, the heat generation is reduced, and the cost is reduced.
High-density mounting can be realized. In the above embodiment, an example of an apparatus configuration in which data of five lines of an input image is converted into binary image data and developed in a bitmap shape in a development area 3a of the image detection unit 3 has been described. , The image data for more or less lines may be handled.

[0011]

In summary, according to the present invention, the following excellent effects can be exhibited. According to the image correction apparatus according to the first aspect of the present invention, the image data of the pixel not subjected to the correction processing is temporarily stored in the image data shift unit for the time required for the correction processing of the image data of the pixel requiring the correction. By performing the process of delaying the output timing in this way, it is possible to eliminate the deviation of the image output positions of the correction target pixel and the non-correction target pixel and to perform high-quality image output. According to the image correction device of the second aspect, in addition to the effect of the first aspect, the capacity of the line buffer memory for temporarily storing input image data of a line that does not need to be corrected is reduced. Therefore, it is possible to reduce the circuit scale, reduce heat generation, reduce cost, and perform high-density mounting.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of an embodiment of an image correction device according to the present invention.

2A is a block diagram illustrating a configuration of a multi-level / two-level image conversion unit of the image correction apparatus illustrated in FIG. 1, and FIG.
FIG. 4 is an explanatory diagram showing a multi-value / two-value data conversion table of a value image conversion unit.

FIG. 3 is an explanatory diagram of an image correction operation in the image correction device shown in FIG.

FIG. 4 is a block diagram showing another embodiment of the image correction device according to the present invention.

FIG. 5 is a block diagram illustrating an example of a conventional image correction device.

FIG. 6 is an explanatory diagram of an image correction operation in a conventional image correction device.

[Explanation of symbols]

1-1 to 1-5 line buffer memory, 1-4 'line buffer memory, 1-5' line buffer memory, 2-1 to 2-5 multi-value / binary image converter, 3 image detector, 3a image Expansion area, 4 image correction section, 5 image selection section, 6 image data shift section, 6a buffer memory, 7 comparison reference data storage section, 8 data comparison section, 1
00 Image correction device, D1 input image data, D2 corrected image data, D3 non-correction target image data, P target pixel.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/40 101D 101C

Claims (2)

[Claims] 1. A plurality of line buffer memories for temporarily storing data of several lines of input image data, and multi-value image data written in each line buffer memory is converted into binary image data. A multivalued / binary image conversion unit; and an image expansion unit that expands the converted binary image data into a bitmap and temporarily stores the image data, and based on the image data expanded in the image expansion unit, The shape of the edge portion is recognized, and if there is a pixel that needs to be corrected based on the result, a correction process is performed on the image data of that pixel, and the image data after the correction process is output. In this case, in the image correction device that outputs the original image data, the time from when the input image data is input to when the image data after the correction processing is output, and the number of pixels for which the correction processing is not performed. An image correction apparatus, comprising: an image data shift unit that changes an output timing of image data of a pixel that is not subjected to a correction process so that a time difference does not occur between the time until the image data is output. . 2. A line buffer memory for temporarily storing image data after a line including a pixel requiring correction among the plurality of line buffer memories. 2. The image correction apparatus according to claim 1, wherein the image correction apparatus is configured to convert the data into data and input the converted data.