JPH08191389A - Image processor - Google Patents

Abstract

PURPOSE: To realize a proper error diffusion processing by utilizing the error data stored in a joint correction data buffer as the main scanning direction first correction data at the time of the relative moving in a sub-scanning direction. CONSTITUTION: An image reading means 2 is started to be moved for a scanning in a sub-scanning direction from an initial location and the scanning of an original is started. Next, the density of each picture element on the first line in the original is successively read in a main scanning direction and is supplied to an error diffusion processing means 12. The operation that the prescribed joint correction data stored in a previous joint correction data buffer 20b is transferred as main scanning direction first error correction data to a present processing line error data memory 14 is executed. When the original is scanned, joint correction data does not exist in the previous joint correction data buffer 20b. Therefore, joint correction data is not transferred to the present processing line error data memory 14. Next, an error diffusion processing is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pixel data which is appropriately subjected to error diffusion processing based on pixel density over the entire area of an original document, although the reading width of the image reading means is smaller than the maximum reading original width. The present invention relates to an image processing device for generating.

[0002]

2. Description of the Related Art Copiers, facsimiles, image readers, etc. are equipped with an image processing device, and such image processing device has an image reading means having a plurality of pixel density reading elements arranged in the main scanning direction. Is moved in the sub-scanning direction relative to the original to read the pixel density in the original image, and pixel data is generated based on the read pixel density.

In the above image processing apparatus, the image reading means in which the pixel density reading elements are arranged over the width corresponding to the maximum read original width, and therefore the read width in the main scanning direction corresponds to the maximum read original width. If the image reading device is equipped with, the image density can be read over the entire area of the original by moving the image reading means once in the sub-scanning direction relative to the original. However, for example, when an image reading means having a reading width of JIS A0 is provided, as is well known to those skilled in the art, from the viewpoint of ensuring the mechanical accuracy, for example, the JI
Compared with the case where an image reading means having a reading width of S · A4 is provided, the cost is significantly increased. Therefore, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-236688, an image reading unit having an image reading width of JIS A4 is provided even when the maximum document reading width is JIS A0. Then, the image reading means is moved not only in the sub-scanning direction but also in the main scanning direction relative to the original, in other words, the reading width of the image reading means is sequentially shifted in the main scanning direction to sequentially move in the sub-scanning direction. It has been proposed to repeat the movement to and thus read the entire area of the original having a width greater than the reading width of the image reading means.

On the other hand, the pixel density reading element of the image reading means discriminates the pixel density in multiple steps (usually 256 steps) and outputs the density data. The pixel data generated based on the density data (transmission and The pixel data used for printing or the like is binary (that is, 0 or 1). Therefore, as disclosed in, for example, Japanese Unexamined Patent Publication No. 6-38040, the error between the multi-level density data and the binary pixel data in each pixel is sorted as the error data regarding the adjacent pixel to correct each pixel data. It has also been proposed to perform an error diffusion process.

[0005]

Therefore, the image reading means is moved relative to the original not only in the sub-scanning direction but also in the main scanning direction, and thus, a width larger than the reading width of the image reading means. When the above-mentioned error diffusion processing is applied to an image processing apparatus in which the entire area of the original having the above is read, when the image reading means is moved in the sub-scanning direction relative to the original in the conventional error diffusion processing method. And the error diffusion processing when the image reading unit is moved in the main scanning direction with respect to the original and then the image reading unit is moved in the sub scanning direction relative to the original again. Because it is never
An appropriate error diffusion process is not realized at the boundary between the scanning area at the time of the relative movement of the image reading means ahead in the sub-scanning direction and the scanning area at the time of the next relative movement of the image reading means in the sub-scanning direction. Pixel data becomes unsuitable at so-called seams.

The present invention has been made in view of the above facts, and its main technical problem is to move the image reading means relative to the document not only in the sub-scanning direction but also in the main-scanning direction. Thus, an improvement was made to the image processing apparatus in the form of reading the entire area of the document having a width larger than the reading width of the image reading means, and the scanning area and the image reading means at the time of the relative movement in the sub-scanning direction ahead of the image reading means. This is to ensure that an appropriate error diffusion process is realized even at the boundary with the scanning region in the next relative movement in the sub-scanning direction.

[0007]

DISCLOSURE OF THE INVENTION As a result of earnest studies, the inventors of the present invention have developed a current processing line error data memory for storing error data relating to a current processing line in the main scanning direction in which an image reading means is located. A seam correction data buffer for storing the final error data in the main scanning direction is provided, and the error data stored in the seam correction data buffer at the time of relative movement in the sub scanning direction before the image reading means is stored in the image reading means. It has been found that the above-mentioned main technical problem can be achieved by using as the correction data in the main scanning direction at the time of the next relative movement in the sub scanning direction.

That is, according to the present invention, as an image processing apparatus that achieves the above-mentioned main technical problems, it has a plurality of pixel density reading elements arranged in the main scanning direction and has a reading width in the main scanning direction. And an image reading unit having a width smaller than the maximum read document width, and a moving unit for moving the image reading unit in the sub-scanning direction and the main scanning direction perpendicular to the main scanning direction with respect to the document. A current processing line error data memory for storing error data in the main scanning direction current processing line having the reading width in which the image reading means is positioned; and a current processing line error data memory next to the current processing line in the sub scanning direction. The next processing line error data for storing the error data in the next processing line having the reading width, in which the image reading means is positioned, A memory, a seam correction data buffer for storing the main scanning direction final error data in the current processing line error data memory, output density data of the pixel density reading element of the image reading means, and the current processing line error data. Error diffusion processing is performed based on the data stored in the memory to generate pixel data, and error data in the current processing line is generated and supplied to the current processing line error data memory, and in the next processing line. The current processing line error data memory is cleared in correspondence with the relative movement of the error diffusion processing means for generating error data and supplying it to the next processing line error data memory and the image reading means in the sub-scanning direction. Transferring the data of the next processing line data memory to the current processing line error data memory, and The main scanning direction final error data of the processed lines that are continuous in the main scanning direction and are stored in the seam correction data buffer are supplied to the current processing line error data memory as main scanning direction first correction data of the current processing line. An image processing apparatus is provided, which comprises:

In a preferred embodiment of the image processing apparatus of the present invention, the maximum read original width exceeds twice the read width of the image reading means in the main scanning direction, and the seam correction data buffer is the next seam. A correction data buffer and a front seam correction data buffer are included, and the data control means sequentially transfers the main scanning direction final error data in the current processing line error data memory to the next seam correction data buffer in the sub scanning direction. The front seam correction data buffer is supplied, and the data in the next seam correction data buffer is transferred to the front seam correction data buffer in response to the relative movement of the image reading means in the main scanning direction. To do. Further, the output density data of the pixel density reading element of the image reading means is multi-step density data, and the pixel data generated by the error diffusion processing means is 2
The error diffusion processing means is configured to allow the error diffusion processing means to output error data regarding the next pixel in the main scanning direction, error data regarding the next pixel in the sub scanning direction, and the next pixel in both the main scanning direction and the sub scanning direction. Generate error data for.

[0010]

In the image processing apparatus of the present invention, the final error data in the main scanning direction at the time of relative movement in the sub scanning direction before the image reading means is stored in the seam correction data buffer,
It is used as correction data in the main scanning direction at the time of the next relative movement of the image reading means in the main scanning direction, and thus the error diffusion process in the scanning area and the image reading means of the image reading means at the time of the relative movement in the sub scanning direction. The error diffusion process in the scanning region at the time of the next relative movement in the sub-scanning direction is appropriately associated, and the appropriate error diffusion process is realized even at the boundary between both scanning regions.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of an image processing apparatus constructed according to the present invention will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 1, the image processing apparatus constructed according to the present invention comprises an image reading means 2. The image reading means 2 includes a large number of pixel density reading elements 4 arranged in the main scanning direction indicated by arrow X.
Have. The pixel density reading element 4 can be composed of, for example, a CCD (charge coupled device). The image reading means 2 is movably mounted in both the main scanning direction X and the sub-scanning direction Y perpendicular to the main scanning direction X, and the image reading means 2 is mounted in the main scanning direction X and the sub-scanning direction. The image reading means 2 is additionally provided with a moving means 6 for appropriately moving to Y. A width W2 that is larger than the reading width W1 of the image reading means 2, for example, four times the width W2.
When reading the entire area of the original 8 having (W2 = 4 × W1), the image reading means 2 is moved in the sub-scanning direction Y from the initial position indicated by the solid line to the position indicated by the alternate long and two short dashes line 2A. At this time, the densities of the pixels 1, 2, 3, ... N of the document 8 are read in the main scanning direction in the lines 1, 2, 3, ... Thus, the pixel densities of the column 1 having the width W1 in the original 8 are read. Then, the image reading means 2 is returned to the initial position, and then moved by the width W1 in the main scanning direction to be positioned at the position indicated by the chain double-dashed line 2B. Then, it is further scanned and moved in the sub-scanning direction Y to the position shown by the chain double-dashed line 2C. At this time, the density of the pixels 1, 2, 3 ... N is read in the main scanning direction in the lines 1, 2, 3 ... Thus, the pixel densities of the column 2 having the width W1 in the original are read. Further, the image reading means 2 is returned to the position shown by the chain double-dashed line 2B, and then moved by the width W1 in the main scanning direction and positioned at the position shown by the chain double-dashed line 2D. Then, it is again moved in the sub-scanning direction Y to the position shown by the chain double-dashed line 2E. At this time, each pixel 1 in the main scanning direction in the lines 1, 2, 3, ...
The densities of 2, 3, ... N are read, and thus the pixel densities of the column 3 having the width W1 of the document are read. Further, the image reading means 2 is returned to the position shown by the chain double-dashed line 2D, and then moved by the width W1 in the main scanning direction to the position shown by the chain double-dashed line 2F. Then, it is again moved in the sub-scanning direction Y to the position indicated by the chain double-dashed line 2G. In this case, the column 4 in the manuscript 8
Line 1 of width W1 that sequentially extends in the main scanning direction,
In the main scanning direction at 2, 3, ...
The density of n is read, and thus the pixel density of the column 4 having the width W1 of the document is read. When the pixel densities are read over the entire area of the original 8 in this manner, the image reading means 2 is returned to the initial position shown by the solid line. If desired, instead of moving the image reading means 2 appropriately to read the original 8 which is stationary, the image reading means 2 is stationary and the original 8 is moved appropriately to read the original 8. You can also do it.

As shown schematically in FIG. 2, the image processing apparatus constructed according to the present invention comprises a central processing unit 10.
(This central processing unit 10 constitutes a data control means for performing various memory and buffer clears, various data supply and transfer, etc. as required), error diffusion processing means 12, current processing line error data memory 14, The next processing line error data memory 16 and the image memory 18 are also provided. Further, the next seam correction data buffer 20a
A seam correction data buffer 20 is also provided, which is composed of a front seam correction data buffer 20b.

The image processing procedure in the image processing apparatus constructed according to the present invention will be described with reference to FIGS. 1 to 3, and particularly FIG. 3. In step S1, a start signal for starting the reading of the original 8 is given. It is determined whether it has been generated. For example, when the start signal is generated by setting the document 8 at a required position and manually operating a reading start switch (not shown), in step S2, the next seam correction data buffer 20a and the previous seam correction data buffer 20b are generated. Is cleared. Then
In step S3, the current processing line error data memory 14 and the next processing error data memory 16 are cleared.
Then, in step S4, the image reading means 2
Starts scanning and moving from the initial position in the sub-scanning direction, and the original 8
The scanning of column 1 is started. Next, in step S5, the densities of the pixels of the first line 1 of the column 1 of the original 8 are sequentially read in the main scanning direction X and are supplied to the error diffusion processing means 12. In step S6, an operation of transferring the predetermined seam correction data stored in the front seam correction data buffer 20b to the current processing line error data memory 14 as the main scanning direction first error correction data is performed. When scanning the column 1 of the manuscript 8, there is no seam correction data in the front seam correction data buffer 20b, so that the seam correction data is not transferred to the current processing line error data memory 14. Next, in step S7, error diffusion processing is performed.

The erroneous diffusion process will be described with reference to FIG. 4. In the illustrated embodiment, the output density data of the pixel density reading element 4 in the image reading means 2 is 25.
The density data has six levels, and the error diffusion processing means 12 generates binary pixel data based on the density data. More specifically, for example, the threshold value is set to “120” and the original 8
1st pixel 1 in the main scanning direction on line 1 of column 1 in FIG.
If the reading density of 1-1 is "90", "90"
Is smaller than the threshold “120”, the error diffusion processing means 1
2 generates “0” as the data of the pixel 1-1-1, and supplies the pixel data to the image memory 18. at the same time,
The density "90" is calculated as an error "+90", and "+36", which is 2/5 of the error "+90", is the next pixel in the main scanning direction, that is, the second pixel 1 in the main scanning direction in line 1 of column 1. The error “+90” is supplied to the current processing line error data memory 14 as the error data regarding −1-2.
2/5 of "+36" is supplied to the next processing line error data memory 16 as error data for the next pixel in the sub-scanning direction, that is, the first pixel 1-2-1 in line 2 of column 1, and also The remaining 1 / of the error "+90"
“+18” which is 5 is supplied to the next processing line error data memory 16 as error data regarding the next pixel in both the main scanning direction and the sub scanning direction, that is, the second pixel 1-2-2 in the line 2 of the column 1. . In FIG. 4, circles represent pixels, numbers in the upper row of circles represent read pixel densities, and numbers in the lower row of circles represent total error data to be added to read image densities (thus, numbers in circles). Pixel data “0” is generated when the sum of the above is less than “120”, and pixel data “1” is generated when it is more than “120”) The error data supplied as the error data for each of the three pixels are shown. If the error data is divided by 5 to generate a numerical value below the decimal point, rounding processing can be performed, for example. Continuing the description with reference to FIG. 4,
When the reading density of the second pixel 1-1-2 in the line 1 of the column 1 of the original 8 is “104”, the error diffusion processing means 1
2 is the error data “+3” stored in the current processing line error data memory 14 at the read density “104”.
6 ”is added to calculate“ 140 ”, and therefore pixel 1-1
"1" is generated as the data of -2. Then, the error (140-255 =) “−115” is calculated, and (−115 × 2/5 =) “−46” among them is calculated as the error regarding the third pixel 1-1-3 in the line 1 of the column 1. The data is supplied to the current processing line error data memory 14 as data, and "-46" is supplied.
Is supplied to the next processing line error data memory 16 as error data regarding the second pixel 1-2-2 in the line 2 of the column 1, and (−115 × 1/5 =) “− 23” in the line 2 of the column 1 is supplied. The error data regarding the third pixel 1-2-3 is supplied to the next processing line error data memory 16.

In step S8 in FIG. 3, it is determined whether or not the process for the last pixel in the line 1 of the column 1 of the original 8 has been repeated. Then, the last pixel 1-1 in the line 1 of the column 1 of the original 8 1-1-
With regard to n, the miscalculation diffusion processing means 12 adds the read density “103” and the error data “+32” stored in the current processing line error data memory 14 to “13”.
5 ”is calculated, and thus“ 1 ”is generated as the data of the pixel 1-1-n. And the error (135-255 =)
“−120” is calculated, and (−120 × 2/5) of that is calculated.
=) "-48" is used as the final error data in line 1 of column 1 (therefore, the first pixel 2 in line 1 of column 2)
The current processing line error data memory 14 is supplied to the current processing line error data memory 14 and "-48" is supplied to the next processing line error data memory 16 as error data concerning the last pixel 1-2-n in the line 2 of the column 1. Supply, (-1
20 × 1/5 =) “−24” as the final error data in line 2 of column 1
Supply to 6.

In step S9 in FIG. 3, the final error data stored in the current processing line error data memory 14 (that is, the first pixel 2 in line 1 of column 2)
"-48" which is error data regarding 1-1) is supplied to the next joint correction data buffer 20a. Step S
At 10, it is determined whether the error diffusion processing has been completed for all the lines 1 to m in the column 1. If the error diffusion processing has not been completed for all the lines 1 to m in column 1, the process proceeds to step S11, the current processing line error data memory 14 is cleared, and the data is stored in the next processing line error data memory 16. The data is transferred to the current process line error data memory 14. Next, returning to step S5, the densities of the respective pixels of the line 2 next to the column 1 in the original 8 are sequentially read in the main scanning direction X and supplied to the error diffusion processing means 12. Then, steps 6 to 10 described above are repeatedly performed.

Pixel 1 in line 2 of column 1 of document 8
The error diffusion processing of 2-1, 1-2-2, ... 1-2-n will be described with reference to FIG. 4. Regarding the first pixel 1-2-1 in the line 2 of the column 1, the reading is performed. The density "54" is added to the error data stored in the current processing line error data memory 14, that is, the error "+36" calculated in the error diffusion process regarding the pixel 1-1-1 is added to calculate "90". Therefore, "0" is generated as the data of the pixel 1-2-1. Then, the error “+90” is calculated, and (+ 90 × 2/5 =) “+36” of the error is calculated as the error data regarding the second pixel 1-2-2 in the line 2 of the column 1, and the current processing line error data memory 14 Supply to
“+36” indicates the first pixel 1-3 in line 3 of column 1
1 is supplied to the next processing line error data memory 16 as error data, and (+ 90 × 1/5 =) “+18” is set as error data concerning the second pixel 1-3-2 in the line 3 of the column 1 The data is supplied to the data memory 16. Regarding the second pixel 1-2-2 in the line 2 of the column 1, the read density “122” and the error data stored in the current processing line error data memory 14, that is, in the error diffusion process for the pixel 1-1-1. The calculated error data “+18”, the error data “−46” calculated in the error diffusion process regarding the pixel 1-1-2, and the error data “+36” calculated in the error diffusion process regarding the pixel 1-2-1. “130” is calculated by adding “+8”, which is the sum of “1”, and thus “1” is generated as the data of the pixel 1-2-2. Then, the error (130-2
55 =) “−125” is calculated, and (−125 ×
2/5 =) "-50" is supplied to the currently processed line error data memory 14 as error data regarding the third pixel 1-2-3 in line 2 of column 1, and "-50" in line 3 of column 1 is supplied. The error data regarding the second pixel 1-3-2 is supplied to the next processing line error data memory 16 and (-
125 × 1/5 =) “−25” is supplied to the next processing line error data memory 16 in the column 1 as error data regarding the third pixel 1-3-3 in the line 3. Regarding the last pixel 1-2-n in the line 2 of the column 1, the read density “123” and the error data stored in the current processing line error data memory 14, that is, the penultimate pixel in the line 1 of the column 1 Error data "+16" calculated in the error diffusion process of 1-1- (n-1) and error data "-48" calculated in the error diffusion process of the last pixel 1-1-n in line 1 of column 1 And line 2 in column 1
In addition, the error data “+40” calculated in the error diffusion process of the penultimate pixel 1-2 (n−1) in “6” is added to calculate “131”. "1" is generated as the data of the pixel 1-2-n. And the error (131-255 =) "-124"
Is calculated, and (−124 × 2/5 = −49.6) among them is calculated.
≈) “−50” as the final error data in line 2 of column 1 (therefore, the first pixel 2 in line 2 of column 2)
(As error data regarding 2-1) to the current processing line error data memory 14 and "-50" is input to the next processing line error data memory 16 as error data regarding the last pixel 1-3-n in line 3 of column 1. Supply, (-1
24 × 1/5 = −24.8≈) “−25” is supplied to the next processing line error data memory 16 as the final error data in line 3 of column 1. Then, in the current processing line error data memory 14, as the final error data in the line 2 of the column 1 (thus, the first error in the line 2 of the column 2 is obtained).
The error "-24" generated in the error diffusion process for the last pixel 1-1-n in line 1 of column 1 and line 2 of column 1)
The error “−74” is stored by adding the error “−50” generated in the error diffusion processing regarding the final pixel in. Then, the final error data "-74" is supplied to the next joint correction data buffer 20a in step S9 in FIG.

Pixel 1-line 2 of column 1 of document 8
The error diffusion processing of 2-1, 1-2-2, ... 1-2-n as described above is repeatedly performed for the lines 3, 4, ... When it is determined in step 10 in FIG. 3 that the error diffusion processing has been completed for all lines 1 to m in column 1, step S1
2, the scanning movement of the image reading means 2 is stopped, and then the image reading means 2 is moved in the direction opposite to the scanning movement in the sub-scanning direction to its initial position, that is, the position shown by the solid line in FIG. Will be returned. And step S
13, the image reading means 2 has a width W in the main scanning direction.
It is moved by a distance corresponding to 1 and positioned at the position indicated by the chain double-dashed line 2B in FIG. Then, in step S14, the next seam correction data buffer 20
The seam correction data stored in a is transferred to the front seam correction data buffer 20b. And step S
At 15, it is determined whether or not the error diffusion processing has been completed for all columns 1 to 4 of the document 8. When the error diffusion processing has not been completed for all 8 to 1 of 8 of the original, the process returns to step S3, and the above-described processing for column 1 of the original 8 is repeatedly performed. Then, in the processing in the column 2 of the document 8, after reading the pixel densities in the lines 1 to m in the column 2 in step S5, the corresponding line joint correction stored in the previous joint correction data buffer 20a in step S6. The data (final error data of the corresponding line in column 1) is supplied to the current processing line error data memory 14. Then, the seam correction data is added to the read density in the error diffusion process for the first pixels of the lines 1 to m in the error diffusion process performed in step S7. To further elaborate on this point, in the error diffusion processing regarding the first pixel 2-1-1 in the line 1 of column 2, the read density "148" is set to the current processing line error data memory 14 from the previous joint correction data buffer 20b. The seam correction data "-48" supplied to the above is added to calculate "100", and thus "0" is generated as the data of the pixel 2-1-1. And the error "+100"
Is calculated, and (100 × 2/5 =) “+40” is supplied to the current processing line error data memory 14 as error data regarding the pixel 2-1-2, and “+40” is calculated for the pixel 2-.
2-1 is supplied to the next processing line error data memory 16 as error data, and again (100 × 1/5
=) “+20” is supplied to the next processing line error data memory 16 as error data regarding the pixel 2-2-2. In addition, in the error diffusion processing regarding the first pixel 2-2-1 in the line 2 of the column 2, the reading density “114”
Then, the seam correction data "-74" supplied from the previous seam correction data buffer 20b to the current processing line error data memory 14 and the error "+40" calculated in the error diffusion process of the pixel 2-1-1 are added. Calculate "80",
Therefore, "0" is generated as the data of the pixel 2-2-1. Then, the error “+80” is calculated and (80
× 2/5 =) "+32" is supplied to the current processing line error data memory 14 as error data regarding the pixel 2-2-2, and "+32" is error data regarding the pixel 2-3-1 as the next processing line error data. The memory 16 is supplied, and (80 × 1/5 =) “+16” is added to the pixel 2-3-2.
Is supplied to the next processing line error data memory as error data. In the error diffusion processing in the first pixel of each line 1 to m in column 2, except that the seam correction data supplied from the previous seam correction data buffer 20b to the current processed line error data memory 14 is added, The image processing procedure for 2 is the same as the image processing procedure for column 1 described above.

Column 2 in step S10 in FIG.
When it is determined that the error diffusion processing has been completed for all the lines 1 to m, the process proceeds to step S12, the scanning movement of the image reading unit 2 is stopped, and then the image reading unit 2 moves to the scanning movement in the sub-scanning direction. On the other hand, it is moved in the opposite direction and returned to the position before the start of the scanning movement of the column 2, that is, the position shown by the chain double-dashed line 2B in FIG. Then, in step S13, the image reading means 2 is moved in the main scanning direction by a distance corresponding to the width W1.
It is located at the position indicated by the chain double-dashed line 2D. Thereafter, in step S14, the seam correction data stored in the next seam correction data buffer 20a is transferred to the previous seam correction data buffer 20b. Then, in step S15, it is determined whether or not the error diffusion processing has been completed for all columns 1 to 3 of the document 8. Since the error diffusion processing for columns 3 and 4 has not been completed, the process returns to step S3, and the above-described processing for column 2 of document 8 is repeatedly performed for columns 3 and 4. After the error diffusion process is completed for column 4 of the manuscript 8,
When it is determined in step S15 that the error diffusion processing has been completed for all the documents 1 to 4 of the document, step S15
In step 16, the image reading means 2 is returned to the initial position, that is, the position shown by the solid line in FIG. 1, and all the image processing procedures are completed.

Thus, in the illustrated embodiment, the seam correction data buffer 20 is composed of the next seam correction data buffer 20a and the previous seam correction data buffer 20b. When the document width W2 is less than or equal to twice the reading width W1 of the image reading means 2, the seam correction data buffer 20 can be composed of a single buffer. Further, in the error diffusion processing in the illustrated embodiment, the error data is distributed and supplied to three adjacent pixels in the main scanning direction and the sub-scanning direction, but if desired, in addition to the three adjacent pixels. For example, the error data can be distributed and supplied to still other pixels adjacent to each of the three pixels.

[0022]

In the image processing apparatus of the present invention, the boundary between the scanning area when the image reading means is relatively moved in the sub scanning direction and the scanning area when the image reading means is relatively moved in the sub scanning direction. In this case, the appropriate error diffusion processing is realized, and even though the reading width of the image reading unit is smaller than the maximum read original width, the pixel data subjected to the appropriate error diffusion processing over the entire area of the original can be generated. .

[Brief description of drawings]

FIG. 1 is a simplified diagram showing a relationship between an image reading unit and a document in an image processing apparatus configured according to the present invention.

FIG. 2 is a block diagram showing main components of an image processing apparatus configured according to the present invention.

FIG. 3 is a flowchart showing an operation procedure of the image processing apparatus shown in FIGS. 1 and 2.

FIG. 4 is a simplified diagram for explaining error diffusion processing in the image processing apparatus shown in FIGS. 1 and 2.

[Explanation of symbols]

 2: Image reading means 4: Pixel density reading element 6: Moving means 8: Original document 10: Central processing unit (data control means) 12: Error diffusion processing means 14: Current processing line error data memory 16: Next processing line error data memory 18: Image memory 20: Seam correction data buffer 20a: Next seam correction data buffer 20b: Previous seam correction data buffer

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H04N 1/403 H04N 1/40 103 A (72) Inventor Yoshiko Uryu 1-2-2 Tamatsukuri, Chuo-ku, Osaka City Within Mita Engineering Co., Ltd.

Claims (3)

[Claims] 1. An image reading unit having a plurality of pixel density reading elements arranged in a main scanning direction and having a reading width in the main scanning direction smaller than a maximum reading document width, and the image reading unit is a document. Relative to the main scanning direction, a moving means for moving in the sub-scanning direction and the main scanning direction at right angles to the main scanning direction, and a main portion having the reading width in which the image reading means is located. A current processing line error data memory for storing error data in the current processing line in the scanning direction, and a next processing line having the reading width in which the image reading means is positioned next to the current processing line in the sub-scanning direction. A next processing line error data memory for storing error data, and a final error in the main scanning direction in the current processing line error data memory. A seam correction data buffer for storing data, an error diffusion process based on the output density data of the pixel density reading element of the image reading means and the data stored in the current processing line error data memory, Error for generating pixel data, generating error data in the current processing line and supplying the error data to the current processing line error data memory, and generating error data in the next processing line and supplying the error data to the next processing line error data memory Corresponding to the relative movement of the diffusion processing means and the image reading means in the sub-scanning direction, the current processing line error data memory is cleared, and the data of the next processing line data memory is changed to the current processing line error data. Data stored in the seam correction data buffer and stored in the seam correction data buffer. The main scanning direction final error data management lines,
An image processing apparatus, comprising: a data control unit that supplies the current processing line error data memory as first correction data in the main scanning direction. 2. The maximum read document width exceeds twice the read width of the image reading means in the main scanning direction, and the seam correction data buffer includes a next seam correction data buffer and a previous seam correction data buffer. The data control means supplies the final error data in the main scanning direction in the current processing line error data memory to the next seam correction data buffer sequentially in the sub scanning direction, and the data reading means of the image reading means. The image processing apparatus according to claim 1, wherein the front seam correction data buffer is cleared and the data of the next seam correction data buffer is transferred to the front seam correction data buffer in response to relative movement in the main scanning direction. . 3. The output density data of the pixel density reading element of the image reading means is multi-step density data, the pixel data generated by the error diffusion processing means is binary, and the error diffusion processing means is The error data for the next pixel in the main scanning direction, the error data for the next pixel in the sub scanning direction, and the error data for the next pixel in both the main scanning direction and the sub scanning direction are generated. Alternatively, the image processing device according to item 2.