JP2002281287A - Image processing system, image reader, image processor, method, computer program and computer-readable memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speed up a process of reducing the moire. SOLUTION: A read resolution R2 is set to twice or more a designated resolution R1 for an image reader 102. The reader 102 averages over image data corresponding to a sensor resolution Ri, using a plurality of adjacent pixel data in the scanning direction, and averages main and sub N*N pixels to make one pixel, thus obtaining image data of the resolution R2. An image processor 101 filters remaining pixels PX not thinned out in a thinning-out resolution changing process of changing the resolution R2 to a resolution R3, one-n-th of R2 (n = integer), thereby reducing the moire, then executes the thinning-out resolution changing process of changing the resolution R2 to the resolution R3 changing the resolution R2 to the resolution R3 for thinning out pixels, and bilinearly changes the resolution R3 after thinning-out, to a finally required designated resolution R1.

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, an image reading apparatus, an image processing apparatus, a method, a computer program, and a computer-readable storage medium. The present invention relates to a device suitable for speeding up processing.

[0002]

2. Description of the Related Art Conventionally, an image scanner using an image sensor has been known as an image reading apparatus. Normal,
When reading an image, the image is read at a specified resolution and output as it is, or is read at a resolution higher than the specified resolution and converted to the specified resolution for output.

[0003] Here, moire is generated when a document printed with halftone dots is scanned due to interference between the arrangement period of the halftone dots and the period of the reading position determined by the resolution. For example, if the original has a screen number of 150
In the case of lines or more, when the resolution is set to about 150 dpi, the period of the moiré becomes long, so that it is conspicuous. The image of the halftone printed document is generally Mg / Cy / Ye
Are regularly arranged, and the color density is represented by its size. When the number of screen lines is 150, the dot density per color is 150 dots / inch, and a different screen angle (for example, 15 ° / 45 ° / 75) for each color.
°). When the reading resolution is 150 dpi, the number of read dots in the main scanning direction is 150 dots / dot.
Inches. Therefore, for example, the screen line angle 45
The halftone dots arrayed at an angle of 10 ° in the main scanning direction (0 ° direction)
6 dots / inch, interference occurs between two different repetition frequencies, and moire fringes of 150-106 = 44 lines / inch (1.7 mm) are formed. The same phenomenon occurs in the sub-scanning direction.

As a general method for reducing moiré, an image is read at a resolution exceeding a specified resolution, all the pixels are subjected to a filtering process, converted to a specified resolution, and output. Are known.

[0005]

However, in the method described in the above-mentioned conventional example, the image is read at a higher resolution than that of the image finally obtained, and the filtering process is performed on all the pixels. , The communication time for exchanging high-resolution data between the image reading device and the image processing device, and the processing time for performing image processing on all pixels of the image. There was a problem. On the other hand, if filter processing is performed on an image with a reduced reading resolution,
The moiré reduction effect of the image is reduced.

The present invention has been made in view of the above points, and has as its object to reduce moiré and speed up processing for reducing moiré.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and when referring to an image processing system, the image processing system according to the present invention changes the reading resolution to read an image. And an image processing apparatus that processes image data read by the image reading apparatus, wherein the image reading apparatus performs processing on the read image data. An image processing unit that performs an averaging process, wherein the image processing device sets a reading resolution determined based on a designated resolution to the image reading device,
Resolution conversion processing means for performing a thinning-out resolution conversion process on the image data of the reading resolution acquired from the image reading device; and resolution conversion processing for pixel data remaining without being thinned out by the resolution conversion process Filter processing means for performing filter processing earlier, and resolution conversion processing means for performing resolution conversion processing of a predetermined method so that the image data having the resolution after the resolution conversion processing of the thinning method has the specified resolution. It is characterized by points.

Further, another image processing system of the present invention comprises:
An image processing system comprising: an image reading device capable of reading an image by changing a reading resolution; and an image processing device for processing image data read by the image reading device, wherein a designated resolution is set in advance. Setting means for setting the reading resolution determined based on the designated resolution to the image reading device when there is a certain relationship with the predetermined resolution being set, and setting the reading resolution acquired from the image reading device to the reading resolution. Resolution conversion processing means for performing resolution conversion processing of a thinning method on image data, and filter processing means for performing filter processing on data of pixels remaining without being thinned out by the resolution conversion processing before the resolution conversion processing The resolution conversion processing of the predetermined method is performed so that the image data having the resolution after the resolution conversion processing of the thinning method has the specified resolution. Characterized in that and a resolution conversion processing means for performing.

Further, another image processing system of the present invention comprises:
An image processing system comprising: an image reading device capable of reading an image by changing a reading resolution; and an image processing device for processing image data read by the image reading device, wherein a designated resolution is set in advance. Setting means for setting the reading resolution determined based on the predetermined resolution to the image reading device when there is a certain relationship with the predetermined resolution being set, and setting the reading resolution acquired from the image reading device to Filter processing means for performing a predetermined type of filter processing on all pixels of the image data, and resolution conversion processing means for performing a predetermined type of resolution conversion processing on the image data after the filter processing so as to have the specified resolution. The feature is that it is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image processing system, an image reading device, an image processing device, a method, a computer-readable storage medium, and a computer program according to the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing an outline of an image processing system according to the present embodiment.
As shown in FIG. 1, the image processing system includes an image processing device 101 and an image reading device 102.

In the image processing apparatus 101, reference numeral 11 denotes a control section for controlling the entire operation, 12 denotes an image processing section for processing image data read by the image reading apparatus 102, 1
Reference numeral 3 denotes an output unit that outputs image data subjected to image processing. In the present embodiment, the control unit 11, the image processing unit 12, and the like function as a setting unit, a resolution conversion processing unit, and a filter processing unit according to the present invention.

In the image reading apparatus 102, 14
Denotes an image processing unit that performs averaging processing (filter processing A and B) described later. In the present embodiment, the image processing unit 14 functions as an image processing unit (first and second averaging processing units) according to the present invention.

FIG. 2 briefly shows an example of the configuration of a so-called flatbed scanner as an example of the image reading apparatus 102. FIG. 2A is a side view, and FIG.
3A is a diagram of the document table 1 of FIG. In FIG. 1, reference numeral 1 denotes a document table, 2 denotes a white reference plate for obtaining shading correction data, 3 denotes an optical unit having an image sensor, and 4 denotes a document reading area of the document table 1. The scanning resolution (reading resolution) of the image reading device 102 can be set in the image processing device 101.

In the image reading apparatus 102 having such a configuration,
By scanning the optical unit 3 in parallel with the document table 1 by a moving means (not shown), the document on the document reading area 4 is read and an image signal is obtained from the image sensor. FIG.
As shown in (b), the X direction is the main scanning direction, and the Y direction is the sub scanning direction (note that the document table 1 is viewed from the back). Hereinafter, “mainly adjacent” means adjacent in the main scanning direction, and “adjacent to sub” means adjacent in the sub-scanning direction.

Next, a processing operation in the image processing system according to the first embodiment will be described with reference to FIGS. FIG. 3 is a flowchart illustrating a processing operation in the image processing system. FIGS. 4A and 4B are diagrams for explaining the filtering process A, wherein FIG. 4A is a diagram showing the processing content of the filtering process A, and FIG. 4B is a diagram showing a filter example. FIG.
FIG. 4 is a diagram illustrating relative sensitivity in the sub-scanning direction. FIG. 6 is a diagram for explaining the filter processing B. FIGS. 7A and 7B are diagrams for explaining the filter, wherein FIG. 7A shows a 3 × 3 cross-type filter, FIG. 7B shows a 5 × 5 diamond-type filter,
(C) is a figure which shows a 7x7 diamond type filter.

When the designated resolution R1 is input to the image processing apparatus 101 (step S100), a resolution determined based on the designated resolution R1 is set to the image reading apparatus 102 as a reading resolution R2 (step S2).
00). Specifically, the reading resolution R2 is set to be at least twice the designated resolution R1. The reason why the reading resolution R2 is set to be twice or more the designated resolution R1 is as follows.
This is because a higher moiré reduction effect can be obtained by performing a filtering process on image data read at a resolution twice or more.

The image processing unit 14 of the image reading device 102
Averaging processing (filter processing A) using a plurality of adjacent pixel data in the main scanning direction is performed on the image data corresponding to Ri which is the resolution of the sensor as the image reading means (step S300). The number of adjacent pixel data to be used is determined in consideration of scaling from the sensor resolution Ri to the reading resolution R2.

Further, the image processing unit 14 of the image reading apparatus 102 averages data N * N pixels of N pixels in the main scanning direction and N pixels in the sub-scanning direction to generate one pixel (filter processing B ) To output image data of resolution R2 (step S400). N in the main scanning direction and N in the sub-scanning direction are determined in consideration of scaling from the sensor resolution Ri to the reading resolution R2.

In the filtering process A, the number of input pixels and the number of output pixels are equal, whereas in the filtering process B,
Since N * N pixels are averaged to be one pixel, the number of output pixels is N * N times the number of input pixels.

By performing the filtering processes A and B on the image reading apparatus 102 and then outputting the same, the image processing time and the transfer time of the image data to the image processing apparatus 101 can be reduced. By performing filter processing on image data equivalent to the resolution Ri of the sensor, it is possible to enhance the moiré reduction effect, thereby increasing the value of N in the filter processing B compared to the case where the filter processing A is not performed. Can be. That is, since a larger number of pixels can be averaged and output to the image processing apparatus 101 at a reduced resolution, the transfer time can be shortened.
Thereafter, the load on the processing performed by the image processing apparatus 101 can be reduced, and the processing can be speeded up.

The image processing unit 12 of the image processing apparatus 101
For image data acquired from the image reading device 102,
A pixel Px that remains without being thinned out when a resolution conversion process of a thinning method described later, that is, a resolution conversion process of thinning the reading resolution R2 to a resolution R3 that is an integer fraction of the resolution R2 is specified (step S500). ).

In the image processing section 12, the pixel P
Filter processing for reducing moire is performed on x (step S600). The filter used for this filter processing is determined so as to include the data of the adjacent pixels on the main and sub sides after performing the resolution conversion processing of the thinning method to the resolution R3.

After the filtering process, the image processing section 12 performs a resolution conversion process of a thinning method, that is, a resolution conversion process of thinning the reading resolution R2 to the resolution R3 (step S700). Since the resolution conversion process here is a thinning-out method, the processing time is short.

Then, a bilinear resolution conversion process is performed from the thinned resolution R3 to the finally required designated resolution R1 (step S800). The reason for using the bilinear conversion method is to obtain a high-quality image free from jaggies and the like.

The image data of the designated resolution R1 obtained in this way is output from the output unit 13 as an output in response to the request.

Hereinafter, a specific example will be described. For example, when the designated resolution R1 is 180 dpi (step S100), the resolution 400 dpi, which is twice or more than that, is set to the image reading apparatus 102 as the reading resolution R2 (step S200).

In the image reading apparatus 102, assuming that the resolution of the sensor is Ri = 1200 dpi, as shown in FIG. Then, an averaging process is performed on four adjacent pixels including the filtering target pixel (step S300). Thus, the reading resolution R2
By performing the filtering process by including the data of the adjacent pixels after scaling to 400 dpi, it is possible to reduce the moire by reducing the interference between the adjacent pixels.

Note that the averaging process of the above four pixels is performed in the manner shown in FIG.
As shown in (a) of (B), the same weighting (that is, 4
Pixel averaging), but as shown in FIG.
By performing weighting, a more natural image can be obtained. As shown in FIG. 5, the weighting ratio of 1: 2: 2: 1 is based on the sensitivity distribution due to the relative movement of the original image and the sensor in the sub-scanning direction.
The determination is made in consideration of the pixel data acquisition range at the time i. That is, weighting is performed according to the relative movement sensitivity of one line in the sub-scanning direction when reading at a reading resolution of R2 = 400 dpi with an image sensor having a sensor resolution of Ri = 1200 dpi.

Further, in the image reading apparatus 102, as shown in FIG. 6, in consideration of the scaling from the sensor resolution Ri = 1200 dpi to the reading resolution R2 = 400 dpi, the data of all nine pixels of three pixels each for the main and sub-pixels is taken into consideration. Are averaged to form one pixel, thereby obtaining a reading resolution R
2 = output image data of 400 dpi (step S
400).

In the image processing apparatus 101, the image reading apparatus 1
For each 400-dpi image data acquired from P.02, each of the main and sub-two pixels is designated as Px (step S
500). Specifying the pixel Px for each of the main and sub two pixels is as follows.
This is because a resolution conversion process for thinning out the resolution R3 = 200 dpi, which is a half of the reading resolution R2 = 400 dpi, will be performed later.

Then, the image processing apparatus 101 performs a filtering process on the pixel data for each of the two main and sub-pixels using a 5 × 5 diamond type filter as shown in FIG. 7B (step S600). In FIG. 7B,
The pixel at the center is the pixel Px to be filtered. Then, by applying a 5 × 5 diamond-type filter, after performing resolution conversion processing of the thinning-out method, the filter processing X is performed by including data of adjacent pixels (pixels denoted by reference numeral 1000 in the figure) on the main and sub sides. Can be. Since moire is generated by interference between adjacent pixels, the interference can be mitigated by filtering including adjacent pixel data. Further, since moiré appears in different directions in the main scanning and sub-scanning directions, the use of a diamond-type filter that can cope with both directions improves the effect of alleviating interference and provides an image with a high moiré reduction effect. it can.

After the filtering process, the image processing apparatus 101 performs a resolution conversion process for thinning out the resolution R3 = 200, which is one half of the reading resolution R2 = 400 dpi (step S700).

Then, image data having a resolution of R3 = 200 dpi after the resolution conversion processing of the thinning method is subjected to scaling processing to a designated resolution R1 = 180 dpi by a bilinear conversion method to obtain image data to be obtained (step S).
800).

As described above, in the first embodiment, since the filter processing A is performed on the image reading apparatus 102 side, image data which is less likely to cause moiré when the image processing apparatus 101 receives image data. Obtainable. Further, since the resolution is reduced by performing the filtering process B on the image reading apparatus 102 side, the transfer speed is also reduced. In addition, the image processing apparatus 101 can obtain an image with a high moiré reduction effect while speeding up the processing by performing the filter processing on the finally required pixels.

For example, in the case where the image reading apparatus 102 does not perform the filtering processes A and B, in order to obtain an image having the same moiré reduction effect, the designated resolution R1 is similarly set.
= 180 dpi, 400 dpi is not enough, and it is necessary to obtain an output image of 600 dpi from the image reading apparatus 102. Then, in the image processing apparatus 101,
Filter processing X is performed by designating each of the three main and sub-pixels as Px to obtain 200 dpi image data that has been subjected to a thinning-out resolution conversion process that leaves only the pixels Px, and then to a designated resolution of 180 dpi by a bilinear conversion method. It is necessary to perform scaling processing.

In this case, the communication data with the image reading apparatus 102 becomes 9/4 times, so that the communication time increases. Also, regarding the filter size of the filter processing X, specifically, it is necessary to use a 7 × 7 diamond type filter shown in FIG.

(Second Embodiment) FIG. 8 is a block diagram showing an outline of an image processing system according to this embodiment.
The configuration is the same as that shown in FIG. 1 except that the image processing unit 14 is omitted, and the same components as those described in FIG. 1 are denoted by the same reference numerals.

Next, a processing operation in the image processing system according to the second embodiment will be described with reference to FIGS. 9 and 10 are flowcharts showing the processing operation in the image processing system. FIG. 11 is a diagram for explaining a filter.

In the image processing apparatus 101, a predetermined resolution R0 is set (step S101). When the designated resolution Rx is input to the image processing apparatus 101 (step S201), it is determined whether or not the designated resolution Rx is equal to or less than twice the predetermined resolution R0 (step S301). The following two processes are performed accordingly.

In step S301, when the designated resolution Rx (= R1) is equal to or less than twice the predetermined resolution R0, the resolution equal to or more than twice the designated resolution R1 is read.
2 is set for the image reading apparatus 102 (step S401). The reason why the reading resolution R2 is set to twice or more the designated resolution R1 is that a higher moire reduction effect can be obtained by performing a filtering process on the image data read with the resolution set to twice or more. is there.

The image reading apparatus 102 reads an image at the set reading resolution R2 and sends the obtained image data to the image processing unit 12 of the image processing apparatus 101.
(Step S501).

The image processing unit 12 of the image processing apparatus 101
For image data acquired from the image reading device 102,
A pixel Px that remains without being thinned out when a resolution conversion process of a thinning method described later, that is, a resolution conversion process of thinning the reading resolution R2 to a resolution R3 that is an integer fraction of the resolution R2 is specified (step S601). ).

In the image processing section 12, the pixel P
x is subjected to filter processing for reducing moiré. The filter used for this filter processing is determined based on a basic filter, and the basic filter has a designated resolution R1 equal to or less than a predetermined resolution R0. It is determined depending on whether or not (step S701).

The basic filter is set to a filter size that includes pixel data adjacent to the main and sub-pixels after conversion to the resolution R3. When the designated resolution R1 is equal to or smaller than the predetermined resolution R0, a 3 × 3 cross filter (see FIG. 7A)
(Step S851), and when the designated resolution R1 exceeds the predetermined resolution R0, a 5 × 5 diamond-type filter (see FIG. 7B) is employed (step S8).
01).

Further, when performing the resolution conversion process from the reading resolution R2 to the resolution R3, the basic filter adopted above is determined based on the magnification of how many pixels of the reading resolution R2 are used to create one pixel of the resolution R3. Then, a filter to be finally applied is created (step S901).

Then, the image processing section 12 uses the filter created in step S901 to generate the pixel P
x is subjected to filter processing for reducing moiré
(Step S1001).

After the filtering process, the image processing unit 12 performs a resolution conversion process of a thinning method, that is, a resolution conversion process of thinning the reading resolution R2 to the resolution R3 (step S1101). Since this resolution conversion processing is a thinning-out method, the processing time is short.

Then, a bilinear resolution conversion process is performed from the decimated resolution R3 to the finally required designated resolution R1 (step S1201). The reason for using the bilinear resolution conversion method is to obtain a high-quality image free from jaggies and the like.

The image data of the designated resolution R1 obtained in this way is output from the output unit 13 as an output in response to the request.

Hereinafter, a specific example will be described. The predetermined resolution R0 is set to 150 dpi (step S101). Fifteen
The reason why 0 dpi is used is that most of the printed materials of halftone dots have a screen number of 150 lines, so that moiré is likely to occur near 150 dpi, and an effective method for avoiding it is more than twice as large. This is because reading is performed at the resolution. In addition, if the predetermined resolution R0 is set to 150 dpi, reading will always be performed at 300 dpi or more in any case. Therefore, by performing filter processing therefrom, the effect of reducing moiré can be enhanced. can do.

As an example, the designated resolution R1 = 120 dp
i (step S201), the predetermined resolution R0
= 150 dpi (= 300 dpi) or less (Step S301), the designated resolution R1 = 1
A resolution 300 dpi, which is twice or more 20 dpi, is set as the reading resolution R2 in the image reading apparatus 102 (step S401).

In the image processing apparatus 101, the image reading apparatus 1
02 is designated as Px for each of the main and sub-pixels in the 300 dpi image data acquired from step S02 (step S
601). Specifying the pixel Px for each of the main and sub two pixels is as follows.
This is because the resolution processing for thinning out the resolution R3 = 150 dpi, which is one half of the reading resolution R2 = 300 dpi, will be performed later.

Further, in the image processing apparatus 101, the designated resolution R1 = 120 dpi is changed to the predetermined resolution R0 = 150 dpi.
i, so that a 3 × 3 cross-type filter (see FIG. 7A) is adopted as a basic filter (step S).
851). Since the reading resolution is changed from R2 = 300 dpi to R3 = 150 dpi, 2 × 2
Since one pixel is formed from the pixels, a filter of scale 20 shown in FIG. 11B is formed by superimposing 3 × 3 cross-type filters (step S901).

The image processing apparatus 101 performs a filtering process on the pixel data of each of the main and sub two pixels using a filter of scale 20 (step S1001).

After the filter processing, the image processing apparatus 101 performs resolution conversion processing for thinning out the resolution R3 = 150 dpi, which is one half of the reading resolution R2 = 300 dpi (step S1101).

Then, the image data having a resolution of R3 = 150 dpi after the resolution conversion processing of the thinning-out method is scaled to a designated resolution of R1 = 120 dpi by a bilinear conversion method to obtain image data to be obtained (step S).
1201).

As another example, the designated resolution R1 =
If the resolution is 250 dpi (step S201), the predetermined resolution R0 is twice the value of 150 dpi (= 300 dpi).
i) Since it is less than or equal to (step S301), the resolution 600 dpi which is twice or more the designated resolution R1 = 250 dpi
i is set to the image reading apparatus 102 as the reading resolution R2 (step S401).

In the image processing apparatus 101, the image reading apparatus 1
02 is designated as Px for each of the main and sub-pixels in the 600 dpi image data acquired from step S02 (step S
601). Specifying the pixel Px for each of the main and sub two pixels is as follows.
This is because the resolution processing for thinning out the resolution R3 = 300 dpi, which is one half of the reading resolution R2 = 600 dpi, will be performed later.

Further, in the image processing apparatus 101, the designated resolution R1 = 250 dpi is replaced by the predetermined resolution R0 = 150 dpi.
Since it exceeds i, a 5 × 5 diamond type filter (see FIG. 7B) is adopted as the basic filter (step S851). Then, the reading resolution R2 = 600 dpi
Is changed to a resolution R3 = 300 dpi from
Since one pixel is formed from the × 2 pixels, the filter of the scale 52 shown in FIG. 11D is prepared by superimposing the 5 × 5 diamond type filters (step S90).
1).

The image processing apparatus 101 performs a filtering process on the pixel data of each of the main and sub two pixels using a filter of scale 52 (step S1001).

After the filtering process, the image processing apparatus 101 performs a resolution conversion process for thinning out the resolution R3 = 300 dpi, which is one half of the reading resolution R2 = 600 dpi (step S1101).

Then, image data having a resolution of R3 = 300 dpi after the resolution conversion processing of the thinning method is subjected to scaling processing to a designated resolution of R2 = 250 dpi by a bilinear conversion method to obtain image data to be obtained (step S).
1201).

As described above, by performing the filtering process on the finally required pixels, the pixel data adjacent to the main and sub-pixels after the conversion to the resolution R3 by the filtering process can be performed at high speed. , And by setting weights for adjacent pixels before zooming, an image with a higher moiré reduction effect can be obtained.

On the other hand, if the specified resolution Rx (= R4) exceeds twice the value of the predetermined resolution R0 in step S301, a resolution four times or more the predetermined resolution R0 is set as the reading resolution R5 to the image reading apparatus 102. Is set (step S411).

When the resolution is increased, a document in which moiré is likely to occur has many screen lines, but a general print document has an upper limit of about 250 screen lines. To prevent moiré, scan at twice the resolution.
In view of the upper limit of the screen line, not very high resolution is required. For this reason, when the specified resolution Rx is twice or more the predetermined resolution R0, the reading resolution R2 is set to be twice or more the specified resolution R1 as described above (step S401). R
If x exceeds twice the predetermined resolution R0, the reading resolution R
Since the resolution becomes unnecessarily high if the resolution 2 is twice or more the designated resolution R1, the resolution is four times or more the predetermined resolution R0 (step S411).

The image reading apparatus 102 reads an image at the set reading resolution R2 and sends the obtained image data to the image processing unit 12 of the image processing apparatus 101.
(Step S511).

The image processing unit 12 of the image processing apparatus 101
Filter processing for reducing moiré is performed on all the images of the image data acquired from the image reading apparatus 102 (step S1011). This filter processing is characterized in that at least pixel data adjacent to the main and sub-pixels is included.

After the filtering process, a bilinear resolution conversion process is performed from the reading resolution R5 to the finally required designated resolution R4 (step S1211). The reason for using the bilinear resolution conversion method is to obtain a high-quality image free from jaggies and the like.

The image data of the designated resolution R4 obtained in this way is output from the output unit 13 as an output in response to the request.

Hereinafter, a specific example will be described. When the designated resolution R1 is 400 dpi (step S20)
1), a value twice as large as the predetermined resolution R0 = 150 dpi (= 3
00 dpi) (step S301), the predetermined resolution R0 = 600 dpi, which is four times or more of 150 dpi.
pi is set as the reading resolution R5 in the image reading apparatus 102 (step S411).

In the image processing apparatus 101, the image reading apparatus 1
As shown in FIG. 7B, a filtering process using a 5 × 5 diamond filter is performed on all the pixels of the image data of 500 dpi acquired from step S02 (step S).
1011). Thus, the effect of reducing moiré can be enhanced by the filter processing in which the adjacent pixels are added to the main and sub pixels.

The image processing apparatus 101 obtains the image data to be obtained by subjecting the image data having the reading resolution R5 = 600 dpi to scaling processing to the designated resolution R4 = 400 dpi by a bilinear conversion method (step S1).
211).

As described above, in the second embodiment, when the designated resolution Rx is at least twice the prescribed resolution R0, the reading resolution R2 is set to be at least twice the designated resolution R1 (step S401). ) While the moiré reduction effect is enhanced, the designated resolution Rx is equal to 2 of the predetermined resolution R0.
If the reading resolution R5 exceeds twice, the reading resolution R5 is set to 2 of the designated resolution R4.
Since the resolution becomes unnecessarily high if the resolution is twice or more, the resolution is set to four times or more the predetermined resolution R0 in order to reduce unnecessary image processing time (step S41).
1). By dividing the processing based on the predetermined resolution as described above, the moire reduction effect is high and the high-speed processing can be performed as the whole system.

(Other Embodiments) In order to operate various devices to realize the functions of the above-described embodiments, an apparatus connected to the various devices or a computer in a system is used in the above-described embodiments. Supply the software program code to realize the functions of
The present invention also includes those implemented by operating the various devices according to programs stored in a computer (CPU or MPU) of the system or apparatus.

In this case, the software program code itself implements the functions of the above-described embodiment, and the program code itself constitutes the present invention. As a transmission medium of the program code, a communication medium (a wired line or a wireless line such as an optical fiber) in a computer network (a WAN such as a LAN or the Internet, a wireless communication network, etc.) system for propagating and supplying the program information as a carrier wave. Etc.) can be used.

Further, means for supplying the program code to a computer, for example, a recording medium storing such a program code constitutes the present invention. As a recording medium for storing such a program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape,
A nonvolatile memory card, a ROM, or the like can be used.

Further, when the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (operating system) or other operating system in which the program code runs on the computer. It goes without saying that such program codes are also included in the embodiments of the present invention when the functions of the above-described embodiments are realized in cooperation with the application software or the like.

Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the function expansion board or the function expansion unit is specified based on the instruction of the program code. It is needless to say that the present invention also includes a case where the CPU or the like provided for performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

The shapes and structures of the respective parts shown in the above embodiments are merely examples of the embodiment for carrying out the present invention, and the technical scope of the present invention is thereby reduced. It should not be interpreted restrictively. That is, the present invention can be implemented in various forms without departing from the spirit or main features thereof.

[0081]

As described above, according to the present invention, it is possible to reduce moiré and speed up the processing for reducing moiré.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an outline of an image processing system according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration of a flatbed scanner.

FIG. 3 is a flowchart illustrating a processing operation according to the first embodiment.

FIG. 4 is a diagram for explaining filter processing A;

FIG. 5 is a diagram illustrating relative sensitivity in the sub-scanning direction.

FIG. 6 is a diagram for explaining filter processing B;

FIG. 7 is a diagram for explaining a filter.

FIG. 8 is a diagram illustrating an outline of an image processing system according to a second embodiment.

FIG. 9 is a flowchart illustrating a processing operation according to the second embodiment.

FIG. 10 is a flowchart illustrating a processing operation according to the second embodiment.

FIG. 11 is a diagram for explaining a filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Image processing apparatus 102 Image reading apparatus 11 Control part 12 Image processing part 13 Output part 14 Image processing part

Claims (28)

[Claims] 1. An image processing system comprising: an image reading device capable of reading an image by changing a reading resolution; and an image processing device for processing image data read by the image reading device. The image reading device includes an image processing unit that performs an averaging process on the read image data, and the image processing device sets a reading resolution determined based on a designated resolution for the image reading device. Setting means, resolution conversion processing means for performing resolution conversion processing of a thinning method on the image data of the reading resolution obtained from the image reading apparatus, and resolution conversion processing means for pixel data remaining without being thinned by the resolution conversion processing. Filter processing means for performing a filter process before the resolution conversion process, and image data of a resolution after the resolution conversion process of the thinning method. The image processing system characterized by comprising a resolution conversion processing means for performing resolution conversion processing of predetermined system such as the above specified resolution. 2. The image processing device according to claim 1, wherein said image processing means includes first averaging processing means for averaging all pixels in the main scanning direction using a plurality of adjacent pixel data. 2. The image processing system according to 1. 3. The image processing system according to claim 1, wherein said first averaging processing means performs averaging processing using a plurality of adjacent pixel data in the main scanning direction. 4. The image processing system according to claim 3, wherein the first averaging processing means performs averaging processing by weighting the plurality of adjacent pixel data in the main scanning direction. 5. The image processing system according to claim 4, wherein the weighting is determined according to a resolution of an image reading unit of the image reading device and the reading resolution. 6. The image processing means includes second averaging processing means for averaging data of a plurality of pixels in the main scanning direction and data of a plurality of pixels in the sub-scanning direction to create one pixel. The image processing system according to claim 1, wherein: 7. The method according to claim 1, wherein the plurality of pixels in the main scanning direction and the plurality of pixels in the sub-scanning direction are determined according to a resolution of an image reading unit of the image reading device and the reading resolution. 7. The image processing system according to 6. 8. The image processing means includes: first averaging processing means for averaging all pixels in the main scanning direction using a plurality of adjacent pixel data; Second averaging processing means for performing averaging processing for averaging data of a plurality of pixels in the sub-scanning direction to create one pixel, and after the averaging processing by the first averaging processing means, 2. The image processing system according to claim 1, wherein an averaging process is performed by the second averaging processing unit, and the image data of the reading resolution is output to the image processing device. 3. 9. An image reading apparatus capable of reading an image by changing a reading resolution, wherein a first means for averaging all pixels in the main scanning direction using a plurality of adjacent pixel data. Averaging processing means, and second averaging processing means for performing averaging processing for averaging data of a plurality of pixels in the main scanning direction and a plurality of pixels in the sub-scanning direction to create one pixel, An image reading apparatus, wherein the averaging processing by the first averaging processing means is followed by the averaging processing by the second averaging processing means to output image data of a required reading resolution. 10. An image reading method using an image reading device capable of reading an image by changing a reading resolution, wherein the method is performed using a plurality of adjacent pixel data for all pixels in a main scanning direction. A first averaging process, and a second averaging process for averaging data of a plurality of pixels in the main scanning direction and a plurality of pixels in the sub-scanning direction to create one pixel; And performing the second averaging process to output image data of a required reading resolution. 11. A computer program for controlling an image reading device capable of reading an image by changing a reading resolution, wherein the computer program uses a plurality of adjacent pixel data for all pixels in the main scanning direction. A first averaging process to be performed, and a second averaging process for averaging data of a plurality of pixels in the main scanning direction and a plurality of pixels in the sub-scanning direction to create one pixel. A computer program for performing the second averaging process after the conversion process to output image data of a required reading resolution. 12. An image processing system comprising: an image reading device that can read an image by changing a reading resolution; and an image processing device that processes image data read by the image reading device. Setting means for setting, for the image reading device, a reading resolution determined based on the specified resolution when the specified resolution has a certain relationship with a predetermined resolution set in advance; Resolution conversion processing means for performing a thinning-out resolution conversion process on the image data of the read resolution described above, and filtering the pixel data remaining without being thinned out by the resolution conversion process before the resolution conversion process. Filter processing means for performing the above-mentioned thinning-out resolution conversion processing on the image data having the predetermined resolution so that the image data of the resolution becomes the specified resolution. The image processing system characterized by comprising a resolution conversion processing means for performing resolution conversion processing equation. 13. The image processing system according to claim 12, wherein the predetermined relation is a relation in which the specified resolution is equal to or less than twice the predetermined resolution. 14. The image processing system according to claim 13, wherein said setting means sets the reading resolution to be at least twice the designated resolution. 15. A filter selecting means for selecting a basic filter based on said predetermined resolution, and said filter processing using said basic filter based on a magnification relationship between said reading resolution and resolution after resolution conversion processing of said thinning method. 13. The image processing system according to claim 12, further comprising: a filter creating unit that creates a filter used for the image processing. 16. The image according to claim 15, wherein the basic filter has a filter size that includes pixel data adjacent to the main and sub pixels with respect to all pixels after the resolution conversion processing of the thinning method. Processing system. 17. The filter creation means creates a filter to be used for the filter process by weighting the basic filter based on a magnification relationship between the reading resolution and the resolution after the resolution conversion processing of the thinning method. The image processing system according to claim 16, wherein: 18. An image processing apparatus for processing image data read by an image reading apparatus, wherein when a specified resolution has a certain relationship with a predetermined resolution set in advance, the image processing apparatus performs processing based on the specified resolution. Setting means for setting a determined reading resolution for the image reading device; resolution conversion processing means for performing a resolution conversion process of a thinning method on image data of the reading resolution acquired from the image reading device; Filter processing means for performing a filtering process on the pixel data remaining without being decimated by the conversion process before the resolution conversion process; and the designated resolution with respect to the image data having the resolution after the decimating resolution conversion process. An image processing apparatus comprising: performing a predetermined-type resolution conversion process. 19. An image processing method for processing image data read by an image reading device, wherein, when a specified resolution has a certain relationship with a predetermined resolution set in advance, the image processing method is performed based on the specified resolution. A setting process of setting a determined reading resolution for the image reading device; a resolution converting process of performing a thinning-out resolution converting process on image data of the reading resolution acquired from the image reading device; A filtering process performed on pixel data remaining without being thinned out by the processing before the resolution conversion process of the thinning method, and the specified resolution for image data having a resolution after the resolution conversion process of the thinning method. And a resolution conversion process of a predetermined method to be performed. 20. A computer program for processing image data read by an image reading device, wherein a designated resolution is based on the designated resolution when the designated resolution has a certain relationship with a preset predetermined resolution. A setting process for setting a reading resolution determined for the image reading device, a resolution conversion process for performing a thinning-out resolution conversion process on image data of the reading resolution acquired from the image reading device, and the resolution A filtering process to be performed before the resolution conversion process on the pixel data remaining without being thinned out by the conversion process; A computer program for causing a computer to execute a system resolution conversion process. 21. An image processing system comprising: an image reading device that can read an image by changing a reading resolution; and an image processing device that processes image data read by the image reading device. Setting means for setting, for the image reading device, a reading resolution determined based on the predetermined resolution when the designated resolution has a certain relationship with a predetermined resolution set in advance; Filtering means for performing filter processing of a predetermined method on all pixels of the image data having the read resolution, and resolution for performing resolution conversion processing of a predetermined method on the image data after the filter processing so as to have the specified resolution. An image processing system comprising: a conversion processing unit. 22. The image processing system according to claim 21, wherein the predetermined relation is a relation in which the specified resolution exceeds a value twice as large as the predetermined resolution. 23. The image processing system according to claim 22, wherein said setting means determines said reading resolution to be four times or more of said predetermined resolution. 24. The filter according to claim 15, wherein the filter used in the filter processing has a filter size including pixel data adjacent to the main and sub pixels of all the pixels of the image data of the reading resolution. Image processing system. 25. An image processing apparatus for processing image data read by an image reading apparatus, wherein, when a designated resolution has a fixed relationship with a preset predetermined resolution, the image processing apparatus performs processing based on the predetermined resolution. Setting means for setting a determined reading resolution for the image reading apparatus; filter processing means for performing a predetermined type of filtering on all pixels of the image data of the reading resolution acquired from the image reading apparatus; An image processing apparatus comprising: resolution conversion processing means for performing resolution conversion processing of a predetermined method so that the image data after the filter processing has the specified resolution. 26. An image processing method for processing image data read by an image reading device, wherein, when a specified resolution has a certain relationship with a predetermined resolution set in advance, the predetermined resolution is set based on the predetermined resolution. A setting process of setting a determined reading resolution for the image reading device; a filtering process of a predetermined method performed for all pixels of the image data of the reading resolution acquired from the image reading device; A resolution conversion process of a predetermined method for performing the specified resolution on the image data. 27. A computer program for processing image data read by an image reading device, wherein, when a specified resolution has a certain relationship with a predetermined resolution set in advance, the computer program is processed based on the predetermined resolution. Setting processing for setting a reading resolution determined for the image reading apparatus, filtering processing of a predetermined method performed for all pixels of the image data of the reading resolution acquired from the image reading apparatus, and after the filtering processing A computer-readable storage medium storing a computer program for causing a computer to execute a resolution conversion process of a predetermined method for performing the above-mentioned designated resolution on the image data. 28. Any one of claims 11, 20, and 27
A computer-readable storage medium storing the computer program described in the section.