JP3825134B2 - Image correction apparatus and image correction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image correction apparatus installed 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. The present invention relates to an image correction apparatus having a function of correcting a deviation of a data output position due to processing.
[0002]
[Prior art]
In digital image forming apparatuses such as laser printers, when performing image forming processing based on multi-value input image data sent from a host computer, an image scanner, etc., an edge is used to smoothly represent the edge portion of the image. Some have an image correction device that performs smoothing correction. In this type of image correction apparatus, a combination of detection of density gradation information of input image data and edge detection and correction based on binary image data, and reflecting the correction data on the input image data results in a high-quality image. The output is obtained.
FIG. 5 is a block diagram showing a configuration of a conventional image correction apparatus. As shown in the figure, the conventional image correction apparatus includes a plurality of line buffer memories that temporarily store data for several lines of an input image in order to develop and detect multi-valued input image data D1 in the form of a bitmap. 11-1 to 11-5 and a multi-value / binary image conversion unit 12-1 for converting multi-value image data written in each of the line buffer memories 11-1 to 11-5 into binary image data, respectively. 12-5 and an image obtained by arranging a large number of storage elements in a matrix in correspondence with each dot position of the input image data so as to develop the converted binary image data into a bitmap and temporarily store it. An image detection unit 13 having a development area (RAM) 13a and the positional relationship of surrounding pixels with respect to the target pixel P of the image data developed on the image development area 13a of the image detection unit 13 A controller (not shown) that outputs, an image correction unit 14 that generates correction data for the target pixel from the position information of the image data, and corrected image data D2 from the image correction unit 14 for the image-corrected pixel are subjected to image correction. The pixel that has not been subjected to is provided with an image selection unit 15 that performs selection processing for outputting multi-valued input image data (non-correction target image data) D3 as it is.
[0003]
In this image correction apparatus, input image data for several lines sent from a computer, an image scanner, or the like is written in the line buffer memories 11-1 to 11-5. The multi-value / binary image conversion units 12-1 to 12-5 are converted into binary image data according to the density. The binary image data obtained by the conversion is sent to the image detection unit 13 and developed into a bitmap image corresponding to the dot pattern of the input image on the image development area 13a. Then, the positional relationship between the surrounding pixels and the target pixel P on the image development area 13 a is detected, and the obtained position information is sent to the image correction unit 15. The image correction unit 15 generates corrected image data D2 for the target pixel P based on the input position information and outputs the corrected image data D2 to the image selection unit 15. For the line including the target pixel P, pixel data is input to the image selection unit 15 as multi-value data other than the data path for performing image correction. Then, the corrected image data D2 from the image correction unit 14 is output as output image data as it is for the pixels that have undergone image correction, and the non-correction image data D3 is output as is for the pixels that have not been subjected to image correction. Since the series of image processing described above needs to be performed in accordance with the timing of image output, it is performed in synchronization with the common image processing reference clock CK.
[0004]
[Problems to be solved by the invention]
However, in the conventional image correction apparatus, the processes in the multi-value / binary image conversion units 12-1 to 12-5, the image detection unit 13, and the image correction unit 14 are performed in synchronization with the common image processing reference clock CK. Therefore, the corrected image data D2 with respect to the non-correction target pixel data D3 input to the image selection unit 15 as multi-value data without performing image correction processing by the number of clocks corresponding to the time required for processing in each of these units. Output timing will be delayed. As a result, a shift in output timing between the corrected image data D2 and non-correction target pixel data D3 appears as a shift in the print output position. Therefore, as shown in FIG. There was a problem that the output positions of the pixels that do not become inconsistent.
The problem to be solved by the present invention is to solve the above-mentioned problems of the conventional technique and move the output position of a normal image that is not subject to correction in accordance with the processing time of edge smoothing correction, thereby correcting pixels that are not subject to correction. An object of the present invention is to provide an image correction apparatus that can output a higher-quality corrected image by adjusting the shift of the image output position of the pixel.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention of claim 1 includes a plurality of line buffer memory for temporarily storing several lines of data of the image data, the image data written in the line buffer memory 2 value A multi-value-binary image conversion unit for converting the image data into the image data; and an image development unit for developing and temporarily storing the binary image data in the form of a bitmap. In the image correction apparatus that combines and outputs the corrected image data obtained by performing the correction process on the image data of the pixel based on the original image data of the pixel that is not subjected to the correction process, the input image data is input. the provided image data shift unit for changing the output timing of the image data of the pixel is not corrected processing according to the time until the image data after the correction processing is output from, the double Of the number of line buffer memories, the input image is binarized by the multi-value / binary image conversion unit up to the line buffer including pixels that need correction, and the later line buffer has already been binarized. As a configuration for inputting image data, the image data is output to the image development unit .
The invention according to claim 2 converts image data written in a plurality of line buffer memories that temporarily store data for several lines of image data into binary image data, and converts the converted binary data An image output by combining the corrected image data obtained by correcting the image data of the pixel based on the image data obtained by developing the image data into a bitmap and the original image data of the pixel not subjected to the correction process. In the correction method, the output timing of image data of pixels that are not subjected to correction processing is changed according to the time from when the input image data is input until the image data after the correction processing is output, and Of the line buffer memory, the input image is binarized up to the line buffer including the pixels that need correction, and the later line buffer is already binarized image data. Characterized by being adapted to output to input data.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
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 apparatus according to the present invention. As shown in the figure, the image correction apparatus 100 temporarily stores data for several lines of input images (5 in this example) in order to develop and detect multi-valued input image data D1 in the form of a bitmap. Line buffer memories 1-1 to 1-5 and multi-value-2 for converting the multi-value image data written in the line buffer memories 1-1 to 1-5 into binary image data, respectively. A matrix of a large number of storage elements corresponding to each dot position of the input image data in order to temporarily store the converted binary image data in the form of a bitmap in the value image conversion units 2-1 to 2-5 And detecting the position of the black pixel with respect to the target pixel P based on the image data developed on the image development area 3a of the image detection unit 3 By doing Thus, a controller (not shown) for recognizing the shape of the boundary portion (edge portion) between the black pixel region and the white pixel region, and correction information (hereinafter referred to as corrected image data) D2 for the position information of the image data. The correction data from the image correction unit 4 for the pixel that has been subjected to the correction process, and multivalued input image data (hereinafter referred to as non-correction target image data) for the pixel that has not been subjected to image correction. The image selection unit 5 that selects to output D3 as it is, the time from when the input image data D1 is input to when the corrected image data D2 is output, and the non-correction target image data D3 are output. An image having a buffer memory 6a that changes the output timing of the image data D3 of the pixels that are not subjected to correction processing so that there is no time difference with the time until It constructed a data shift section 6.
[0007]
FIG. 2A is a block diagram illustrating a configuration of the multi-value / binary image conversion units 2-1 to 2-5. The multi-value-to-binary image conversion units 2-1 to 2-5 include a comparison reference data storage unit 7 that stores and holds reference multi-value data, and multi-value input image data D1 and comparison reference data storage unit 7. A data comparison unit 8 that compares the stored multi-value data and generates binary output data of “1” or “0” according to the table shown in FIG. A process of detecting the gradation of the data D1 and replacing the input image data with binary data with a certain density as a reference is performed.
[0008]
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. The multi-value / binary image conversion units 2-1 to 2-5 convert the obtained image data 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 developed into a bitmap image corresponding to the dot pattern of the input image on the development area 3a. Then, the positional relationship of the surrounding pixels with respect to the target pixel P on the development area 3 a is detected, and the obtained position information is sent to the image correction unit 4. In the image correction unit 4, correction data for the target pixel P is generated based on the input position information and output to the image selection unit 5. For the line including the target pixel P, image data of pixels other than the image data of the target pixel P is input to the image selection unit 5 through the image data shift unit 6 as multi-value data. Then, the corrected image data D2 from the image correction unit 4 is output as output image data for the pixels that have undergone image correction, and the non-correction target image data D3 is output for pixels that have not been subjected to image correction.
Since the series of image processing described above needs to be performed in accordance with the timing of image output, it is performed in synchronization with the common image processing reference clock CK.
[0009]
Therefore, in the conventional image correction device, the multi-value-to-binary image conversion units 2-1 to 2-5, the image detection unit 3, and the image correction unit 4 are not subject to correction by the number of clocks corresponding to the time required for processing. Since the output timing of the corrected image data D2 is delayed with respect to the image data D3, the output positions of the corrected image data D2 and the non-correction target image data D3 do not match as shown in FIG. It was.
On the other hand, in the image correction apparatus 100 according to the present embodiment, the image data shift unit 6 is provided in the middle of the line that guides the non-correction target image data D3 from the line buffer memories 1-1 to 1-5 to the image selection unit 5. As a result, there is no time difference between the time from when the input image data D1 is input until the corrected image data D2 is output and the time until the non-correction target image data D3 is output. In addition, it is possible to temporarily store the non-correction target image data D3 in the image data shift unit 6 and delay the output timing for the time required for the correction process. By this delay processing, as shown in FIG. 3, it is possible to eliminate the deviation of the output positions of the corrected image data and the non-correction target image data, and to output an image with the positional relationship of the pixels matching the input image.
[0010]
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 corresponding to the number of lines in the pixel matrix of the development area 3a of the image detection unit 3. However, it is necessary to hold the multi-value input image data up to the line including the target pixel P, and the line buffer memories 1-4 and 1-5 for temporarily storing the image data of the subsequent lines are as follows. 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, the input image data after the line including the pixel of interest P is preliminarily stored as binary image data in the line buffer memories 1-4 ′, 1 It is configured to input to −5 ′. 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 ′ and 1-5 ′ after the line including the target pixel P have a capacity of 1/8. That's okay. Further, in this case, since the image data converted into binary values by the multi-value / binary conversion unit 2-3 is configured to be input to the line buffer memories 1-4 ′ and 1-5 ′, a special circuit is provided. There is no need to add.
Therefore, when the circuit of the line buffer memory unit and the multi-value-to-binary conversion unit is configured by a device such as a gate array, it is possible to realize a reduction in circuit scale, reduction in heat generation, cost reduction, high-density mounting, and the like. .
In the above-described embodiment, the description has been given by taking as an example an apparatus configuration that converts data for five lines of an input image into binary image data and develops it in the development region 3a of the image detection unit 3 in a bitmap form. The image data for a larger number or a smaller number of lines may be handled.
[0011]
【The invention's effect】
According to the present invention, the input image is binarized by the multi-value / binary image conversion unit up to the line buffer including the pixels that need to be corrected among the plurality of line buffer memories. Since the binarized image data is input, the capacity of the line buffer memory that does not need to be corrected can be reduced, so that the circuit scale, heat generation, cost reduction, and high cost can be reduced. Density mounting is possible.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of an embodiment of an image correction apparatus according to the present invention.
2A is a block diagram showing a configuration of a multi-value / binary image conversion unit of the image correction apparatus shown in FIG. 1, and FIG. 2B is a multi-value / binary data of the multi-value / binary image conversion unit. It is explanatory drawing which shows a conversion table.
3 is an explanatory diagram of an image correction operation in the image correction apparatus shown in FIG.
FIG. 4 is a block diagram showing another embodiment of the image correction apparatus according to the present invention.
FIG. 5 is a block diagram illustrating an example of a conventional image correction apparatus.
FIG. 6 is an explanatory diagram of an image correction operation in a conventional image correction apparatus.
[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-level / binary image conversion unit, 3 image detection unit, 3a image Development area, 4 image correction unit, 5 image selection unit, 6 image data shift unit, 6a buffer memory, 7 comparison reference data storage unit, 8 data comparison unit, 100 image correction device, D1 input image data, D2 corrected image data , D3 Non-correction target image data, P pixel of interest.

Claims (2)

A plurality of line buffer memory for temporarily storing several lines of data of the image data, and the multi-level -2 value image converting unit that converts the image data written in the line buffer memory to binary image data, 2 An image development unit that develops and temporarily stores image data of a value in the form of a bitmap, and performs a correction process on the image data of the pixel based on the image data developed in the image development unit In an image correction apparatus that synthesizes and outputs data and original image data of pixels that are not subjected to correction processing,
An image data shift unit that changes the output timing of image data of pixels that are not subjected to correction processing according to the time from when the input image data is input until the image data after the correction processing is output ;
Of the plurality of line buffer memories, the input image is binarized by the multi-value / binary image conversion unit up to a line buffer including pixels that need correction, and the subsequent line buffer is already binarized. An image correction apparatus that outputs the processed image data to the image development unit . An image obtained by converting image data written in a plurality of line buffer memories that temporarily store data for several lines of image data into binary image data, and developing the converted binary image data into a bitmap shape In the image correction method for combining and outputting the corrected image data obtained by performing the correction process on the image data of the pixel based on the data and the original image data of the pixel on which the correction process is not performed,
The output timing of image data of pixels that are not subjected to correction processing is changed according to the time from when the input image data is input until image data after the correction processing is output, and the plurality of line buffer memories Of these, the image correction method is characterized in that the input image is binarized up to the line buffer including the pixels that need correction, and the later line buffer inputs and outputs the binarized image data. .

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