JP4160913B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus that performs image processing on input image data.

  In an image forming apparatus such as a digital color copying machine, cyan (based on color image data (red (R), green (G), and blue (B) density value data) of a document read by a scanner) C), magenta (M), yellow (Y), and black (BK) toners are superposed on a sheet so that a full color image can be formed by an electrophotographic method.

  In this type of image forming apparatus, by performing predetermined image processing on color image data read by a scanner, the color of an original image is not reproduced faithfully but is close to a color recognized by a person. Some can be converted to color (expected color) and output. For example, if you scan a clear sky image in summer and a cold winter image with a scanner, the clear sky color (blue) in summer will be darker than faithfully reproducing each sky color. However, if the color of the winter cold sky (blue) is converted to a lighter color, the person who sees the output image will see that each sky color is closer to the person's remembered sky color. feel. By performing the process of converting the color of the document image to the expected color (expected color correction process), an error between the actual color of the document image and the color recognized by the person based on the memory can be filled.

  Therefore, since the color of the recorded image differs between the document to be read by the scanner (original document) and the paper (generation document) after image formation based on the image of the original document read by the scanner, When the image is formed by scanning again with the scanner, the expected color correction process is further performed on the image data of the generation document converted to the expected color, and an image of a color completely different from the expected color is formed. There is a problem that it ends up.

  Conventionally, a configuration that can recognize whether an original set on a scanner is an original document or a generation document has been proposed (see, for example, Patent Document 1). The expected color correction process is performed only when the image of the original document is read by the scanner, and the expected color correction process is not performed when the image of the generation document is read by the scanner.

According to the configuration disclosed in Patent Document 1, when an image of an original document is read by a scanner and image formation is performed, a predetermined tracking pattern is recorded on the output paper (generation document). Therefore, if the original set on the scanner is read in advance by the scanner (pre-scan) and it is determined whether or not the tracking pattern is recorded on the original, it can be determined whether or not the original is a generation original.
JP-A-9-186901

However, in the configuration as described in Patent Document 1, if a document is pre-scanned and it is not determined whether or not a tracking pattern is included in the document image, it is determined whether or not the document is a generation document. I can't.
Therefore, the image formation time is increased by the time required for pre-scanning, and a mechanism (so-called automatic document feeder) that automatically feeds and reads a plurality of documents one by one to the scanner side, for example, is adopted. In this case, there is a problem that it is impossible to determine whether the document is a generation document because pre-scanning cannot be performed.

  The present invention has been made under such a background, and it is possible to determine whether or not a document is a generation document without performing pre-scanning, and to perform different image processing depending on the determination result. An object is to provide an apparatus.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a first image processing means for performing first image processing suitable for a case where the input image data is image data of a generation document. 221, 231, 241) and second image processing means for performing second image processing different from the first image processing on the input image data in parallel with the first image processing (222, 232, 242), original determination means (21) for determining whether or not the input image data is image data of a generation original (original printed by the image forming apparatus), and input image data by the original determination means. When it is determined that the image data is a generation document image data, the image data after the first image processing is output, and the input image data is generated. When it is judged not to be the image data of the manuscript has an output switching means (25) for outputting the image data after the second image processing is performed, the document discrimination means, from the input image data Halftone dot data removing means (211) for removing halftone dot data having a screen line number greater than a predetermined number of lines, and halftone dot data having a screen line number greater than the predetermined number of lines is removed by the halftone dot removing means. If the number of halftone dot data included in the image data after being processed is equal to or greater than a predetermined threshold, it is determined that the input image data is the image data of the generation original, and if it is less than the predetermined threshold, the input image data is the generation original. The image processing apparatus (20) is characterized by comprising discrimination means (212) for discriminating that the image data is not the image data .

The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter.
According to this configuration, the first image processing and the second image processing are performed in parallel on the input image data, and the first image processing is performed depending on whether or not the input image data is the image data of the generation document. It is possible to switch between outputting image data after the image processing is performed and image data after the second image processing is performed.

  Therefore, when such a configuration is adopted in the image forming apparatus, an original image is scanned by performing a main scan (reading a document for performing an image forming operation based on the read image data). While performing the first and second image processing on the data, it is determined whether or not the input image data is the image data of the generation document, and the first image processing is performed according to the determination result. It is possible to switch between output of the later image data and the image data after the second image processing is performed. That is, it is possible to determine whether or not a document is a generation document without performing a pre-scan, and different image processing can be performed according to the determination result.

As a result, the image formation time can be shortened by the time required for the prescan, and, for example, a prescan as in the case where a mechanism (a so-called automatic document feeder) that allows a plurality of documents to be read one by one is adopted. Even if it cannot be performed, it can be determined whether the document is a generation document.
In general, the number of screen lines of a printed material (original document) is determined by the material, and the image in the photographic area of a magazine or catalog using coated paper or art paper is usually 150 lines (150 lpi (line per inch)) or more. Has screen line count. On the other hand, an image in a photographic area formed on a paper (generation original) after image formation based on image data of the original original usually has a screen line number of less than 150 lpi. In particular, in an image forming apparatus that performs image formation by an electrophotographic process, the number of screen lines is reduced (for example, to about 141 lpi) due to variation in the size of halftone dots, etc., so the number of screen lines around 150 lpi is used as a reference. By doing so, the original document and the generation document can be distinguished well.
According to the above configuration, halftone dot data having a screen line number equal to or greater than a predetermined line number (for example, 150 lpi) is removed from the input image data. When halftone dot data is completely (or most) removed from the image data and the screen line number is less than the predetermined line number, the whole (or most) halftone dot data remains in the input image data. It will be. Therefore, whether or not the input image data is the image data of the generation document can be well determined based on the number of halftone dot data included (remaining) in the image data after the halftone dot data is removed. Different image processing can be performed according to the determination result.
The halftone dot data removing means (211) performs a predetermined filtering process on the input image data (image data of the photographic area), so that the predetermined line is obtained from the input image data (image data of the photographic area). Halftone dot data having a screen line number greater than or equal to the number may be removed.
In this case, the halftone dot data removing unit (211) may perform a filtering process using one filter for the input image data (image data of the photographic area), or may include a plurality of filters. May be used to perform filtering.
According to a second aspect of the present invention, the first image processing includes an image (for example, image color) corresponding to the image data after the first image processing output by the output switching unit is performed. The image processing device (20) according to claim 1, further comprising a process (221) for converting the input image data so as to approximate an image corresponding to the input image data (for example, an image color). .

  According to this configuration, when the input image data is the image data of the generation document, an image corresponding to the image data after the first image processing output from the output switching unit is input by the first image processing. Since it is approximated to an image corresponding to the image data (faithful color reproduction processing), if an image is formed based on the image data after the first image processing, the image corresponding to the input image data is faithfully reproduced. be able to.

Therefore, a process (for example, an expected color correction process) for further converting the image is performed on the image data of the generation document, and an image different from the desired image can be prevented from being formed .

According to a third aspect of the present invention, in the first image processing and the second image processing, halftone dot data having a screen line number greater than or equal to the predetermined number from input image data (image data of a photographic area), respectively. The image processing apparatus (20) according to claim 1 or 2, further comprising a process (231, 232) for removing the image.
According to this configuration, the image data after the first image processing and the image data after the second image processing each have halftone dot data having a screen line number equal to or greater than the predetermined line number (for example, 150 lpi). The image data is removed. Therefore, when the image data after the first image processing or the image data after the second image processing is input again to the image processing apparatus, the image data (generation document) Since the halftone dot data is completely removed from the image data), it can be determined well whether the input image data is the image data of the generation document, and different image processing can be performed according to the determination result. .

  The processing (231, 232) for removing the halftone dot data may include a predetermined filtering process for the input image data (image data of the photographic area). In this case, if the filter processing is performed using different types of filters for the first image processing and the second image processing, the periodicity of halftone dots overlaps and moire (density unevenness) occurs. Can be suppressed.

According to a fourth aspect of the present invention, at least one of the first image processing and the second image processing is different in an image area of the input image data and an area other than the image area of the input image data. Processing may be performed.

Embodiments of the present invention will be specifically described below with reference to the drawings.
FIG. 1 is a schematic sectional view showing an internal configuration of a digital color copying machine 1 according to an embodiment of the present invention.
Referring to FIG. 1, this digital color copying machine 1 has color image data (red (R), green (G), and blue (B) density value data) of a document read by a scanner (not shown). Based on the above, the image forming unit 2 forms a full-color image by electrophotography by sequentially superimposing cyan (C), magenta (M), yellow (Y), and black (BK) toner on a sheet. This is a so-called tandem type digital color copying machine.

The image forming unit 2 includes four substantially cylindrical photosensitive drums corresponding to the respective color toners (photosensitive drum 3M corresponding to magenta, photosensitive drum 3C corresponding to cyan, photosensitive drum 3Y corresponding to yellow, and black). Are arranged on a straight line at a predetermined interval from each other.
Around each of the photosensitive drums 3M to 3BK, LSUs (laser scanning units) 4M, 4C, 4Y, 4BK, developing devices 5M, 5C, 5Y, 5BK, transfer devices 6M, 6C, 6Y, 6BK, and cleaning devices 7M, 7C, 7Y, 7BK, etc. are arranged in association with each other. At the time of image formation, the photosensitive drums 3M to 3BK are rotated counterclockwise in FIG. 1, and the surfaces of the photosensitive drums 3M to 3BK are uniformly charged to a positive potential by a main charger (not shown). Thereafter, light based on the image data is irradiated on the surfaces of the photosensitive drums 3M to 3BK by the LSUs 4M to 4BK, so that so-called electrostatic latent images are formed on the surfaces of the photosensitive drums 3M to 3BK. Each of the developing devices 5M to 5BK contains toner of each color charged to a negative potential, and the surface of each of the photosensitive drums 3M to 3BK on which the electrostatic latent image is formed is formed by the developing devices 5M to 5BK. Corresponding color toner is electrostatically attached to form a toner image.

At the time of image formation, the paper stored in the paper cassette 8 is sent out to the paper transport path 10 by the paper feed roller 9, transported to the image forming unit 2 side through the paper transport path 10, and the leading edge thereof. When the section reaches the registration roller 11, it is temporarily stopped.
A conveyance belt 12 that is wound around a pair of belt rollers 121 with a predetermined tension is disposed downstream of the registration rollers 11 in the sheet conveyance direction. The conveyor belt 12 is disposed below the photosensitive drums 3M to 3BK, and the upper surfaces of the upper portions thereof are in contact with the surfaces of the four photosensitive drums 3M to 3BK. At the time of image formation, the pair of belt rollers 121 are rotated in the clockwise direction in FIG. 1, whereby the conveyance belt 12 is rotated in the clockwise direction, and the sheet fed from the registration rollers 11 at a predetermined timing is conveyed to the conveyance belt 12. Is conveyed downstream.

  Below the photosensitive drums 3M to 3BK, transfer devices 6M to 6BK are arranged with the upper portion of the conveyor belt 12 interposed therebetween. In the process in which the paper is transported between the transport belt 12 and each of the photosensitive drums 3M to 3BK, the transfer device 6M to 6BK has a voltage having a polarity (negative potential) opposite to that of the toner (negative potential). By applying each, the toner adhering to the surface of the corresponding photosensitive drums 3M to 3BK is electrostatically attracted to the transfer devices 6M to 6BK and transferred to the paper. The toner remaining on the surfaces of the photosensitive drums 3M to 3BK after the toner image transfer is collected by cleaning devices 7M to 7BK provided corresponding to the photosensitive drums 3M to 3BK.

  The sheet on which the toner image has been transferred is guided to the fixing device 13 by the conveying belt 12 and subjected to a predetermined fixing process, and then discharged onto a discharge tray 14 arranged outside the apparatus. The fixing device 13 includes a heat roller 131 that is heated to a predetermined fixing temperature and a pressure roller 132 that is pressed against the heat roller 131 with a predetermined fixing pressure. As the paper passes between the heat roller 131 and the pressure roller 132, the toner particles transferred to the paper are heated and pressurized to be melted and fixed on the paper.

  In general, the number of screen lines of a printed material (original document) is determined by the paper quality, and an image in a photographic area (gradation part) of a magazine or a catalog using coated paper or art paper is usually 150 lines (150 lpi (line per). inch)) or more screen lines. On the other hand, an image in a photographic region formed on a paper (generation original) after image formation based on an original original image read by a scanner usually has a screen line number of less than 150 lpi. In an image forming apparatus that forms an image by electrophotography, such as the digital color copying machine 1 according to this embodiment, the number of screen lines is reduced (for example, to about 141 lpi) due to variation in the size of halftone dots. Therefore, if the screen line number around 150 lpi is used as a reference, the original document and the generation document can be distinguished well.

FIG. 2 is a block diagram showing an electrical configuration of the digital color copying machine 1.
Referring to FIG. 2, the scanner 15 includes a light source 151 for irradiating light toward a document, and a CCD image sensor 152 that receives reflected light from the document and outputs an analog signal. . The CCD image sensor 152 is configured by arranging a plurality of CCD elements in a line, and the electric main scanning in the arrangement direction of these CCD elements and the originals of the light source 151 and the CCD image sensor 152 are performed. Reading of an original image is achieved by sub-scanning by relative movement. The analog signal output from the CCD image sensor 152 is A / D converted by the A / D converter 16 into multi-value (for example, 0 to 255) digital data (image data), and then input to the image processing unit 20. Is done.

  The image processing unit 20 is for performing predetermined image processing on the image data (input image data) input from the scanner 15. Each density value data of red (R), green (G), and blue (B) input to the image processing unit 20 is cyan (C), magenta (M), It is converted into each density value data of yellow (Y) and black (BK).

The image processing unit 20 includes, for example, a microcomputer, and when the microcomputer executes program processing, the determination unit 21, the first color correction processing unit 221, the first filter processing unit 231, and the first γ A correction processing unit 241, a second color correction processing unit 222, a second filter processing unit 232, a second γ correction processing unit 242, and the like are functionally provided.
The image data input from the scanner 15 to the image processing unit 20 is input to the determination unit 21, the first color correction processing unit 221, and the second color correction processing unit 222. In the image processing unit 20, processing by the determination unit 21, a series of processing (first image processing) by the first color correction processing unit 221, the first filter processing unit 231, and the first γ correction processing unit 241, and the second color A series of processing (second image processing) by the correction processing unit 222, the second filter processing unit 232, and the second γ correction processing unit 242 is performed in parallel.

  The determination unit 21 is for determining whether or not the input image data is image data of a generation document, and includes a halftone data removal processing unit 211 and a comparison unit 212. The halftone data removal processing unit 211 removes halftone dot data having a screen line number greater than or equal to a predetermined number of lines from the photo area by performing a filtering process using a Gaussian filter on the photo area of the input image data. The process (halftone data removal process) is performed.

FIG. 3 is a diagram illustrating a specific example of a Gaussian filter used in the halftone data removal process.
In the halftone data removal processing, a Gaussian filter of 5 rows × 5 columns (see FIG. 3A), a Gaussian filter of 7 rows × 7 columns (see FIG. 3B), and a Gaussian filter of 9 rows × 9 columns (see FIG. 3B). Filter processing is performed using any one of the three types of Gaussian filters shown in FIG. That is, each pixel in the photographic area of the input image data is sequentially set as a target pixel, and a Gaussian filter is applied to the density value of the target pixel and its surrounding pixels (number of pixels corresponding to the size of the Gauss filter centering on the target pixel). The calculation used is performed.

  As a result of the halftone data removal process, when a Gaussian filter of 5 rows × 5 columns (see FIG. 3A) is used, halftone dot data of 175 lpi or more is removed from the photograph area, and 7 rows × 7 columns. When a Gaussian filter (see FIG. 3B) is used, halftone dot data of 150 lpi or more is removed from the photograph area, and a 9-row × 9-column Gaussian filter (see FIG. 3C) is used. The halftone dot data of 120 lpi or more is removed from the photograph area.

Referring to FIG. 2 again, the comparison unit 212 of the determination unit 21 compares the number of halftone data (dispersion value) included in the photo area of the image data after the halftone data removal process with a predetermined threshold value TH. It is determined whether or not the input image data is the image data of the generation document.
For example, when halftone dot data removal processing is performed using a 7-row × 7-column Gaussian filter as shown in FIG. 3B, halftone dot data of 150 lpi or more is removed from the photograph area of the input image data. However, since the entire (or most) photographic area of the original document has a screen line number of 150 lpi or more, halftone data removal processing is performed on the image data (input image data) of the original document. In such a case, halftone dot data is completely (or most) removed from the input image data. On the other hand, the photographic area of a generation document usually has a screen line number of less than 150 lpi as a whole (or most), so halftone data removal processing is performed on the image data (input image data) of the generation document. In this case, all (or most) halftone dot data remains in the input image data.

Therefore, if the number of halftone data included in the image data after the halftone data removal process is equal to or greater than the predetermined threshold value TH, it can be determined that the input image data is the image data of the generation document, If the number of halftone dot data included in the image data is less than the threshold value TH, it can be determined that the input image data is the image data of the original document.
The first color correction processing unit 221 converts the input image data so that the color of the image corresponding to the processed image data approximates the color of the image (original image) corresponding to the input image data (faithful reproduction color) Correction processing). Therefore, the image data after the faithful reproduction color correction processing is performed by the first color correction processing unit 221 is processed by the first filter processing unit 231 and the first γ correction processing unit 241 to obtain the image data. When the image forming unit 2 forms an image based on the above, an image in which the color of the original image is faithfully reproduced is recorded on the paper.

  The first filter processing unit 231 applies, for example, a 9-row × 9-column Gaussian filter shown in FIG. 3C to the photographic region of the image data after the processing by the first color correction processing unit 221 is performed. The filter processing used is performed. That is, each pixel in the photographic area of the image data is set as a target pixel in order, and a Gaussian of 9 rows × 9 columns with respect to density values of the target pixel and its peripheral pixels (9 rows × 9 columns centered on the target pixel). An operation using a filter is performed. Thereby, the dot data of 120 lpi or more is removed from the photo area of the image data.

The first γ correction processing unit 241 is for correcting the gradation characteristics of the image data after the processing by the first filter processing unit 231 is performed to obtain linear output characteristics.
The second color correction processing unit 222 causes the color of the image corresponding to the processed image data to be a color (expected color) that is close to the color recognized by the person who viewed the image (original image) corresponding to the input image data. A process for converting input image data (expected color correction process) is performed. Therefore, the image data after the expected color correction processing is performed by the second color correction processing unit 222 is processed by the second filter processing unit 232 and the second γ correction processing unit 242, and the image data is processed. When image formation is performed on the basis of the image forming unit 2, an image in which the color of the original image is converted to the expected color is recorded on the paper.

  The second filter processing unit 232 applies, for example, a 7 × 7 Gaussian filter shown in FIG. 3B to the photographic region of the image data after the processing by the second color correction processing unit 222 is performed. The filter processing used is performed. That is, each pixel in the photographic region of the image data is set as a target pixel in order, and Gaussian of 7 rows × 7 columns with respect to density values of the target pixel and its peripheral pixels (pixels of 7 rows × 7 columns centering on the target pixel) An operation using a filter is performed. As a result, halftone dot data of 150 lpi or more is removed from the photo area of the image data.

The second γ correction processing unit 242 performs processing for correcting the tone characteristics of the image data after the processing by the second filter processing unit 232 and enhancing contrast (contrast γ correction processing).
The image processing unit 20 includes a selector 25 that selects image data to be output to the image forming unit 2 based on the determination result by the determination unit 21. The discrimination result data by the discrimination unit 21, the image data after the processing by the first γ correction processing unit 241, and the image data after the processing by the second γ correction processing unit 242 are respectively input to the selector 25. Is done. When the determination unit 21 determines that the input image data is the image data of the generation document, the selector 25 outputs the image data after the processing by the first γ correction processing unit 241 to the image forming unit 2. To do. On the other hand, when the determination unit 21 determines that the input image data is not the image data of the generation document, the selector 25 sends the image data after the processing by the second γ correction processing unit 242 to the image forming unit 2. Output.

  In this embodiment, a series of image processing (first image processing) by the first color correction processing unit 221, the first filter processing unit 231, and the first γ correction processing unit 241, and the second color are performed on the input image data. Whether a series of image processing (second image processing) by the correction processing unit 222, the second filter processing unit 232, and the second γ correction processing unit 242 is performed in parallel, and whether the input image data is image data of a generation document Accordingly, the selector 25 can switch between output of image data after the first image processing and image data after the second image processing are output.

  Accordingly, the scanner 15 performs a main scan (reading of a document for performing an image forming operation by the image forming unit 2 based on the read image data), and the first and second input image data based on the main scan is scanned. While performing the second image processing, it is determined whether or not the input image data is the image data of the generation document, and according to the determination result, the image data after the first image processing, and the first The selector 25 can switch which image data is output after the second image processing is performed. That is, it is possible to determine whether or not a document is a generation document without performing a pre-scan, and different image processing can be performed according to the determination result.

As a result, the image forming time can be shortened by the time required for the prescan, and for example, a mechanism (so-called automatic document feeder) that automatically feeds and reads a plurality of documents one by one to the scanner 15 side. Even when pre-scanning cannot be performed as in the case of adoption, it is possible to determine whether the document is a generation document.
In this embodiment, when the input image data is the image data of the generation document, the image forming unit 2 records an image in which the color of the document image is faithfully reproduced on the paper. The expected color correction process is further performed on the image data, and an image different from the desired image can be prevented from being recorded on the paper.

  In the above embodiment, the image data after the first image processing has the halftone dot data of 120 lpi or more removed from the photographic area, and the image data after the second image processing has the data of 150 lpi or more from the photographic area. Halftone data has been removed. Accordingly, image formation is performed in the image forming unit 2 based on the image data after the first image processing or the image data after the second image processing, and the image on the paper (generation document) after the image formation is again. When read by the scanner 15, the halftone data is completely removed from the input image data (generation original image data) by the halftone data removal processing unit 211. Therefore, it can be well determined whether or not the input image data is the image data of the generation document, and different image processing can be performed according to the determination result.

The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims.
For example, in at least one of the first image processing and the second image processing described above, an image processing (character region) different from the image processing for the photographic region is performed on the region (character region) other than the photographic region of the input image data. Edge emphasis processing for emphasizing the contour, etc.) may be performed.

  The first image processing and the second image processing are not limited to performing processing for converting the color of the image corresponding to the input image data, and may be performed as long as different image processing is performed in parallel. Processing for converting other parameters may be performed. In this case, the first image processing is not limited to including processing (faithful reproduction color correction processing) for faithfully reproducing the color of the image (original image) corresponding to the input image data, but other than the color of the original image. A process for faithfully reproducing the parameters may be included. Further, the second image processing is not limited to including processing for converting the color of the document image into the expected color (expected color correction processing), but converts the color of the document image into a predetermined color different from the expected color. For example, or may include a process for converting parameters other than the color of the document image.

  The halftone data removal processing unit 211 is not limited to a calculation using a Gaussian filter of 7 rows × 7 columns as shown in FIG. 3B, but 5 rows × 5 as shown in FIG. An operation using other Gaussian filters such as a Gaussian filter of columns or a 9-row × 9-column Gaussian filter as shown in FIG. In this case, the configuration may be such that only halftone dot data within a predetermined line number range can be removed by using a combination of a plurality of types of Gaussian filters.

  The determination unit 21 is not limited to determining whether or not the input image data is the image data of the generation document based on the number of screen lines of the input image data. The identification image (tracking pattern, barcode, etc.) recorded on the generation document may be detected to determine whether the input image data is the image data of the generation document based on the presence or absence of the identification image. . In this case, the digital color copying machine 1 may be configured to include means for recording an identification image on a sheet during image formation.

The generation document may include not only a document printed by a digital color copying machine based on the original document but also a document printed by another image forming apparatus such as a digital printer.
In the above embodiment, the tandem type digital color copying machine has been described as an example. However, in the present invention, for example, a toner image is formed by attaching a plurality of colors of toner to the surface of one photosensitive drum, and the toner image is formed. The present invention is also applicable to other digital image forming apparatuses such as a digital color copying machine of a type capable of transferring the image to a sheet.

1 is a schematic sectional view showing an internal configuration of a digital color copying machine according to an embodiment of the present invention. 1 is a block diagram showing an electrical configuration of a digital color copying machine. It is a figure which shows the specific example of the Gaussian filter used for a halftone data removal process.

Explanation of symbols

20 Image processing unit 21 Determination unit 211 Halftone data removal processing unit 221 First color correction processing unit 222 Second color correction processing unit 231 First filter processing unit 232 Second filter processing unit 241 First γ correction processing unit 242 Second γ correction Processing unit 25 selector

Claims (4)

First image processing means for performing first image processing suitable for input image data when the input image data is image data of a generation document ;
Second image processing means for performing second image processing different from the first image processing in parallel with the first image processing on the input image data;
Document discriminating means for discriminating whether or not the input image data is image data of a generation document;
If the input image data is determined to be the image data of the generation original by the original determination means, the image data after the first image processing is output, and the input image data is not the image data of the generation original. Output switching means for outputting the image data after the second image processing is performed ,
The document discrimination means
Halftone dot data removing means for removing halftone dot data having a screen line number equal to or greater than a predetermined line number from input image data;
If the halftone dot data included in the image data after the halftone dot data having the screen line number equal to or larger than the predetermined line number is removed by the halftone dot removing means is greater than or equal to a predetermined threshold value, the input image data is the generation document. Discriminating means for discriminating that the input image data is not the image data of the generation document if it is less than a predetermined threshold value;
The image processing apparatus characterized by comprising a. In the first image processing, the input image data is set such that an image corresponding to the image data after the first image processing output by the output switching unit approximates an image corresponding to the input image data. The image processing apparatus according to claim 1, further comprising: 3. The first image processing and the second image processing each include processing for removing halftone dot data having a screen line number equal to or greater than the predetermined number from input image data. An image processing apparatus according to 1. At least one of the first image processing and the second image processing performs different image processing in a photographic area of input image data and an area other than the photographic area of input image data. the image processing apparatus according to any one of claims 1 to 3.

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