JP4856607B2 - Image forming apparatus, image processing apparatus, and image processing program - Google Patents

Description

  The present invention relates to an image forming apparatus, an image processing apparatus, and an image processing program, and more particularly to a technique for determining a halftone dot region.

In an image forming apparatus such as a copying machine, a method of performing gradation reproduction by a dither method or a density pattern method is generally employed in order to reproduce a halftone when an image is formed on a recording sheet. In these methods, (a) when an image printed on a document is a halftone image, a periodic striped pattern (moire) that does not exist in the document appears in the copied (copied) image. ) A line segment constituting a character or the like in a document or simply a line drawing has a problem that the line segment and the edge of the line drawing are cut off due to the dither processing and the image quality is deteriorated. Therefore, an image processing technique disclosed in Patent Document 1 below has been proposed. In this image processing technique, when a document image is input, each region in the document is determined as to what kind of image (a continuous tone region such as a photograph, a halftone dot region, or even a character region) is formed. This is to solve the problems (a) and (b) described above by applying processing suitable for each area.
Japanese Patent No. 2621879

  However, when the halftone dot region is determined from the image read by the image reading unit of the image forming apparatus using the image processing technique disclosed in Patent Document 1, depending on the screen line number of the halftone dot and the halftone dot angle, There is a possibility that it cannot be judged accurately. Since the halftone dot region cannot be accurately determined in this way, it is difficult to accurately determine other portions other than the halftone dot region, for example, character portions. Therefore, if the printed recording paper is used as a copy source document and further copying (so-called generation copying) is performed by the image forming apparatus, image processing suitable for each of the above areas cannot be performed, and for example, halftone dot reproduction is not accurate. There may be a case where the image quality is deteriorated such that a character portion is crushed, color reproduction is not preferable, or gradation is poor.

  The present invention has been made to solve the above-described problem, and has an object to more accurately determine a halftone dot region in an image to be formed by an image forming apparatus than in the past. And

According to a first aspect of the present invention, an image data acquisition unit that acquires image data to be subjected to image formation;
A digital watermark information extraction unit that extracts digital watermark information embedded in the image data acquired by the image data acquisition unit;
A region determination unit that determines a halftone dot region from the image data acquired by the image data acquisition unit using the halftone dot information indicated by the digital watermark information extracted by the digital watermark information extraction unit;
An image processing unit for each region that performs image processing predetermined for each region on the image data of each region determined by the region determination unit;
An image forming unit that forms an image on an image forming medium, the image data obtained by the image data obtaining unit and subjected to the image processing by the image processing unit for each area ,
The halftone dot information indicated by the digital watermark information is halftone dot type specifying information for specifying a halftone dot type including at least one of the number of halftone lines and the halftone dot angle .

  In the present invention, the digital watermark information extraction unit extracts the digital watermark information embedded in the image data acquired by the image data acquisition unit, and the halftone dot determination unit converts the halftone dot information indicated by the extracted digital watermark information. Based on this, the halftone dot region in the image data acquired by the image data acquisition unit is determined and extracted. In this way, the halftone dot determination unit does not rely on information indicating the halftone dot obtained directly from the image data itself acquired by the image data acquisition unit, or the halftone dot obtained directly from the image data itself. In addition to the information shown, by performing the region determination using the halftone dot information indicated by the digital watermark information, erroneous detection of halftone dot information that is likely to occur when detecting halftone dot information from the image data itself does not occur. The halftone dot region in the image data acquired by the image data acquisition unit can be accurately determined and extracted. Since the halftone dot region can be accurately extracted in this manner, other parts other than the halftone dot region, for example, the character portion can be accurately extracted. Therefore, even when generation copy is performed, an image suitable for each region is obtained. It is possible to perform processing and prevent image quality deterioration (character portions are crushed, color reproduction is not preferable, gradation is poor, etc.). As a result, the present invention can perform image formation by reproducing the entire image including the halftone dot region of the image read by the image forming apparatus more accurately than in the past.

  According to the present invention, by using the halftone dot number or halftone dot type identification information as the halftone dot information, the characteristics and properties of the halftone dots in the image data can be specifically specified. In addition, by adopting the halftone dot number or halftone dot type identification information that is widely used in general as the digital watermark information, the digital watermark can be used even between different manufacturers of image forming apparatuses. Sharing and decoding of information becomes easy.

The invention of claim 2 is an image forming apparatus according to claim 1, an electronic watermark indicating the halftone dot information using the dot forming process for the halftone region by the regional image processing unit A digital watermark information generation unit for generating information;
The image processing unit for each region embeds the digital watermark information generated by the digital watermark information generation unit in the image data determined as a halftone dot region by the region determination unit.

  According to this invention, the image processing unit for each region embeds the digital watermark information indicating the halftone dot information generated by the digital watermark information generation unit in the image data determined as the halftone dot region by the region determination unit. The image forming unit forms an image of the image data in which the digital watermark information is embedded on the image forming medium. Therefore, for example, even when an image forming medium on which an image is formed by the image forming apparatus is further copied by the image forming apparatus, it is possible to determine a halftone dot region based on the digital watermark information described above. .

According to a third aspect of the present invention, there is provided an image data acquisition unit that acquires image data to be subjected to image formation;
A digital watermark information extraction unit that extracts digital watermark information embedded in the image data acquired by the image data acquisition unit;
An area determination unit for determining a halftone dot area from the image data acquired by the image data acquisition unit using the halftone dot information indicated by the digital watermark information extracted by the digital watermark information extraction unit ;
The halftone dot information indicated by the digital watermark information is an image processing apparatus that is halftone dot type specifying information for specifying a halftone dot type including at least one of the number of halftone lines and the halftone dot angle .

The invention according to claim 4 is an image processing program for causing a computer to perform image processing,
A digital watermark information extraction unit that extracts digital watermark information embedded in the image data acquired by the image data acquisition unit;
A computer including a region determination unit that determines a halftone region from the image data acquired by the image data acquisition unit using the halftone dot information indicated by the digital watermark information extracted by the digital watermark information extraction unit; allowed to function,
The dot information indicated by electronic watermark information, Ru dot type specifying information der specifying the halftone dot type including at least one screen ruling or dot angle.

  According to these inventions, the digital watermark information extraction unit extracts the digital watermark information embedded in the image data acquired by the image data acquisition unit, and the halftone dot determination unit uses the halftone dot information to generate image data. A halftone dot region in the image data acquired by the acquisition unit is determined and extracted. In this way, the halftone dot determination unit does not rely on information indicating the halftone dot obtained directly from the image data itself acquired by the image data acquisition unit, or the halftone dot obtained directly from the image data itself. By performing area determination using the halftone dot information in addition to the information shown, the halftone dot area in the image data acquired by the image data acquisition unit can be accurately determined and extracted.

  According to the present invention, it is possible to more accurately determine the halftone dot region in an image that is an object of image formation acquired by the image forming apparatus than ever before.

  Hereinafter, an image forming apparatus, an image processing apparatus, and an image processing program according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing an internal configuration of a multifunction machine 1 which is an example of an image forming apparatus according to an embodiment of the present disclosure. The multifunction machine 1 has functions such as a copy function, a printer function, a scanner unit function, and a facsimile function. The multi-function device 1 includes a main body 2, a stack tray 3 disposed on the left side of the main body 2, a document reading unit 5 disposed on the top of the main body 2, and an upper side of the document reading unit 5. And a document feeding unit 6 disposed.

  An operation unit 47 is provided at the front part of the multifunction machine 1. The operation unit 47 displays a start key 471 for a user to input a print execution instruction, a ten key 472 for inputting the number of copies to be printed, operation guide information for various copying operations, and the like. A display unit 473 formed of a liquid crystal display or the like having a touch panel function, a reset key 474 for resetting setting contents set in the display unit 473, and a stop key for stopping a printing (image forming) operation being executed 475 and a function switching key 477 for switching between a copy function, a printer function, a scanner unit function, and a facsimile function.

  The document reading unit (image data acquisition unit) 5 includes a scanner unit 51 including a CCD (Charge Coupled Device) sensor and an exposure lamp, and a document table 52 and a document reading slit 53 made of a transparent member such as glass. . The scanner unit 51 is configured to be movable by a drive unit (not shown). When reading a document placed on the document table 52, the scanner unit 51 is moved along the document surface at a position facing the document table 52, and the document image is scanned. The image data acquired while scanning is output to the control unit 10 (FIG. 2). Further, when reading a document fed by the document feeding unit 6, the document is moved to a position facing the document reading slit 53 and synchronized with the document feeding operation by the document feeding unit 6 via the document reading slit 53. The image of the original is acquired and the image data is output to the control unit 10.

  The document feeding unit 6 includes a document placing unit 61 for placing a document, a document discharge unit 62 for discharging a document whose image has been read, and a document placed on the document placing unit 61. A document transport mechanism 63 including a paper feed roller (not shown), a transport roller (not shown) and the like for feeding the paper one by one to a position facing the document reading slit 53 and discharging it to the document discharge section 62 is provided. The document conveyance mechanism 63 further includes a sheet reversing mechanism (not shown) that reverses the document and reversely conveys the document to a position facing the document reading slit 53, and scans both sides of the document through the document reading slit 53. 51 can be read.

  The document feeding unit 6 is provided so as to be rotatable with respect to the main body unit 2 so that the front side thereof can move upward. By moving the front side of the document feeder 6 upward to open the upper surface of the document table 52, the operator can place a read document, for example, a book in a spread state, on the upper surface of the document table 52. It has become.

  The main body 2 includes a plurality of paper feed cassettes 461, a paper feed roller 462 that feeds the recording paper from the paper feed cassette 461 one by one and transports it to the recording unit 40, and a recording paper transported from the paper feed cassette 461. And a recording unit 40 for forming an image.

  The recording unit (image forming unit) 40 is acquired by the static elimination device 421 that neutralizes residual charges from the surface of the photosensitive drum 43, the charging device 422 that charges the surface of the photosensitive drum 43 after static elimination, and the scanner unit 51. A laser beam is output based on the obtained image data to expose the surface of the photosensitive drum 43, and an electrostatic latent image is formed on the surface of the photosensitive drum 43; Formed on the photosensitive drum 43 and developing devices 44K, 44Y, 44M, and 44C that form toner images of each color of cyan (C), magenta (M), yellow (Y), and black (K) on the photosensitive drum 43. A transfer drum 49 on which the toner images of the respective colors are transferred and overlaid, a transfer device 41 for transferring the toner image on the transfer drum 49 to the paper, and heating the paper on which the toner image is transferred. And a fixing device 45 for fixing the toner image onto the sheet. Note that toner is supplied to each color of cyan, magenta, yellow, and black from a toner supply container (toner cartridge) (not shown). In addition, conveyance rollers 463 and 464 that convey the recording paper that has passed through the recording unit 40 to the stack tray 3 or the discharge tray 48 are provided.

  When forming images on both sides of the recording paper, the recording unit 40 forms an image on one side of the recording paper, and then the recording paper is nipped by the conveyance roller 463 on the discharge tray 48 side. In this state, the conveyance roller 463 is reversed to switch back the recording paper, and the recording paper is sent to the paper conveyance path L and conveyed again to the upstream area of the recording unit 40, and an image is formed on the other surface by the recording unit 40. Thereafter, the recording paper is discharged to the stack tray 3 or the discharge tray 48.

  FIG. 2 is a functional block diagram showing a schematic configuration of the multifunction machine 1 shown in FIG. FIG. 3A is a diagram schematically illustrating how digital watermark information is extracted from a document image, and FIG. 3B is a schematic diagram illustrating how digital watermark information is combined with an image to be output to a recording sheet. FIG. The multifunction machine 1 includes a control unit 10 that controls the operation of the entire apparatus. The control unit 10 includes a document reading unit 5 including a scanner unit 51 and the like, a document feeding unit 6 including a document transport mechanism 63, and the like. Connected to the recording unit 40 including the developing device 44, the operation keys such as the start key 471 and the numeric keypad 472, the operation unit 47 including the display unit 473, the image memory 7, the HDD 8, the network I / F unit 9, and the image processing unit 11. Has been.

  The image memory 7 functions as a work area of the control unit 10 or is not shown through image data of a document (for example, a halftone document) read by the document reading unit 5 or a network I / F unit 9 described later. This is a memory for temporarily storing image data transmitted from the external device.

  An HDD (Hard Disk Drive) 8 is composed of, for example, a hard disk or the like, and includes image data of a document image read by the document reading unit 5, image data transmitted from an external device, and an output format set for the image data. And the like are stored.

  The network I / F unit 9 transmits and receives various data to and from a personal computer connected via a network such as the Internet or a LAN using a network interface or the like under the control of the control unit 10. It is.

  The image processing unit 11 performs various images on document image data (image data) obtained by reading a document by the document reading unit 5 or image data obtained from an external personal computer via the network I / F unit 9. The processing is performed. The image processing unit 11 includes a region determination unit 111, a digital watermark information extraction unit 112, a digital watermark information generation unit 113, a region-specific image processing unit 114, and a filter processing unit 115.

  The area determination unit 111 determines, for example, each of a halftone area, a character area, and a photographic area from the original image data read by the original reading unit 5. The region determination information determined by the region determination unit 111 is sent to the region-specific image processing unit 114, and the region-specific image processing unit 114 performs image processing for each region based on the region determination information.

The area determination unit 111 (1) when detecting a character area, each pixel constituting the original image is sequentially set as a target pixel, the target pixel and peripheral pixels are extracted, and an edge detection filter is applied to these pixels. By performing filter processing using (for example, a Laplacian filter), edge detection processing for detecting edge pixels constituting the contour of the image is performed. Then, when an edge is detected by this edge detection process, the region determination unit 111 determines that the target pixel is an edge pixel, and determines a character region based on the edge pixel. For example, the region determination unit 111 calculates a difference value between each of the luminance values of the target pixel and eight neighboring pixels adjacent to the target pixel, and the difference value having a value larger than a predetermined threshold is equal to or greater than a certain number (for example, If there are four or more), it is determined that the target pixel is an edge pixel constituting the character. The region determination unit 111 extracts a region in which the edge pixel is equal to or greater than a predetermined threshold as a character region. Here, the luminance is expressed by, for example, Expression (1).
Y = 0.299R + 0.587G + 0.114B Formula (1)
However, Y represents luminance, R represents the gradation of the red component, G represents the gradation of the green component, and B represents the gradation of the blue component. By using the luminance represented by the expression (1), it is possible to extract a character region in consideration of human vision. The character area determination shown here is merely an example.

  Then, the area determination unit 111 determines (2) an area composed of pixels other than the pixels determined as the character area from the pixels constituting the original image as a non-character area. Further, the region determination unit 111 detects a pixel in the photographic region and a pixel in the halftone dot region from the pixels constituting the non-character region. (2-1) The area determination unit 111, for example, sequentially sets each pixel constituting the image data of the non-character area as a target pixel, and sums the density differences of pixels adjacent to each other in a predetermined area centered on the target pixel. And the total is compared with a threshold determined depending on the average density difference in the predetermined area. If the total is equal to or less than the threshold, it is determined that the pixel of interest is a pixel in the photographic area.

  (2-2) Further, the area determination unit 111 sequentially sets each pixel constituting the image data of the non-character area as a target pixel, and in a predetermined area centered on the target pixel, the main scanning direction or the sub-scanning direction The number of change points of a plurality of pixels arranged in a line is calculated, and when the calculated number of change points is equal to or greater than a threshold, it is determined that the target pixel is a pixel in the halftone dot region. Note that the non-character area determination, halftone area determination, and photo area determination shown here are merely examples. Then, the area determination unit 111 reads the halftone dot information associated with the digital watermark information extracted by the digital watermark information extraction unit 112 from the halftone dot information storage unit 81 at the time of the halftone dot area determination, and the read network Using the dot information, the halftone dot region is determined from the data of the original image read by the original reading unit 5 (details will be described later).

  The digital watermark information extracting unit 112 extracts digital watermark information (embedded information) embedded in the document image data read by the document reading unit 5. This digital watermark information indicates halftone dot information including the number of halftone lines and the halftone angle representing the characteristics and properties of halftone dots contained in image data on a document.

  The digital watermark information is embedded as a latent image in an image formed on a document. For example, different types of dither patterns are used for the latent image portion, which is digital watermark information, and the background portion other than that, and the pattern density of one pattern is determined as the resolution at the time of document reading by the document reading unit 5 (scanner unit 51). Is set to a pattern density that is less than or equal to the resolution at the time of reading the document by the document reading unit 5 (scanner unit 51). Therefore, even if the original document is viewed, it is difficult for a person to visually recognize the digital watermark information. However, if the image on the document is optically read by the document reading unit 5 (scanner unit 51), FIG. As shown in a), the digital watermark information extraction unit 112 can determine the digital watermark information from the read image.

  The digital watermark information generation unit 113 generates digital watermark information to be embedded in an image that is a target of image formation by the recording unit 40. The digital watermark information generation unit 113 uses the different types of dither patterns at the time of halftone dot forming processing by the image processing unit 114 for each area for the halftone dot region in the image to be imaged by the recording unit 40. Digital watermark information including the number of used halftone lines and halftone angle is generated. When the image processing unit by area 114 embeds the digital watermark information generated by the digital watermark information generation unit 113 in the original image read by the original reading unit 5, as shown in FIG. The same digital watermark information as the digital watermark information present in the original image read by the unit 5 is embedded in the image data to be image-formed by the recording unit 40.

  The image processing unit by region 114 performs image processing predetermined for each region on the image data of each region determined by the region determination unit 111. For example, the image processing unit for each region 114 performs different predetermined image processing depending on each of the halftone dot region, the character region, and the photo region. The area-specific image processing unit 114 performs a halftone dot forming process on the image data determined to be a halftone dot area.

  The filter processing unit 115 divides individual pixels constituting an image to be subjected to image processing (an image to be read by the document reading unit 5 and subjected to image formation by the recording unit 40) with surrounding pixels. Image processing that gives a special effect to the image by performing an operation is performed. This image processing is, for example, blurring, edge enhancement, edge extraction, noise processing by expansion processing or reduction processing, mosaic processing, posterization, or the like.

  The image data that has been subjected to the image processing in the image processing unit 11 by each unit is output to the recording unit 40 or the like.

  The control unit 10 includes a ROM (Read Only Memory) that stores a control program of the multifunction device 1, a RAM (Random Access Memory) that temporarily stores data, and a micro information processing that reads and executes a control program from the ROM. The apparatus is configured to execute processing for controlling the entire apparatus in accordance with instruction information input from the operation unit 47 and detection signals from various sensors provided in various parts of the multifunction machine 1.

  Note that the image processing unit 11, the region determination unit 111 included in the image processing unit 11, the digital watermark information extraction unit 112, the digital watermark information generation unit 113, the image processing unit by region 114, and the filter processing unit 115 are included. May be composed of a circuit or the like, but the control unit 10 may function as the image processing unit 11 and each of the above units in accordance with a program stored in the HDD 8 or the like. In addition, the HDD 8 stores an image processing program according to an embodiment of the present invention, and the image processing program is an area formed by each unit of the image processing unit 11 for original image data read by the recording unit 40. The CPU 100 may execute determination processing, image forming operation control by the recording unit 40, and the like. In this case, the multifunction machine 1 is an example of a computer in the scope of claims.

  The image processing apparatus according to an embodiment of the present invention includes a document reading unit 5, a digital watermark information extraction unit 112, and an area determination unit 111.

  Next, area determination and image formation processing during the copying operation of the multifunction machine 1 will be described. FIG. 4 is a flowchart showing area determination and image formation processing during the copying operation of the multifunction device 1.

  When the operator places a document on the document placement unit 61 or the document table 52 and inputs a copy operation start instruction by operating the start key 471 (YES in S1), the control unit 10 causes the document reading unit 5 to Then, the document on the document placement unit 61 or the document table 52 is read (S2).

  Subsequently, the digital watermark information extraction unit 112 extracts the digital watermark information embedded in the original image data from the original image data read by the original reading unit 5 (S3). The digital watermark information extracting unit 112 extracts latent image data, which is digital watermark information, from the document image data, and specifies the number of halftone lines and the halftone angle indicated by the digital watermark information. That is, the number of halftone lines and the halftone angle are embedded in the document image data as the digital watermark information.

  The area determination unit 111 determines whether each part of the document image data is a halftone dot area, a character area, or a photographic area, and the above-described detection methods (1), (2), (2-1) ( The determination of the halftone dot area is performed using the halftone dot information indicated by the extracted digital watermark information (S4). That is, the area determination unit 111 performs, for example, the direction in which the number of change points of a plurality of pixels is calculated when the halftone dot area determination of (2-2) described above in the area determination process is performed, or the direction indicated by the dot angle or the direction The halftone dot region is detected with the direction orthogonal to the threshold value and the threshold value of the number of change points as a value reflecting the number of halftone dots. However, the method of determining the halftone dot area by the area determining unit 111 is not limited to the method.

  As a result, the area determination unit 111 performs halftone dot area determination on the original image read by the original reading unit 5 and the number of halftone lines actually used when forming the halftone dots in the image formed on the original. And the halftone dot angle, the halftone dot area can be accurately extracted from the original image read by the original reading unit 5, and in response to this, the character area and the photographic area, which are other areas, can be extracted. Can be extracted accurately.

  The image processing unit for each area 114 performs image processing for each area based on the area determination information determined by the area determination unit 111 (S5). The area-specific image processing unit 114 performs a halftone dot forming process on the image data determined to be a halftone dot area.

  In addition, the digital watermark information generation unit 113 generates digital watermark information including halftone dot identification information including the number of halftone lines and the halftone angle used in the halftone dot formation processing by the image processing unit for each area 14 in S5. (S6). The area-specific image processing unit 114 includes the generated electronic data in the image data of the halftone dot region in the original image data read by the original reading unit 5 and subjected to the halftone dot forming process in S5. The watermark information is embedded (S7). When the digital watermark information extraction process in S3 is performed accurately, the digital watermark information to be embedded is the same as the digital watermark information extracted in S3.

  The control unit 10 is document image data read by the document reading unit 5 and includes a halftone dot region in which the new digital watermark information is embedded and another region. As described above, the image processing unit Then, the recording unit 40 causes the recording unit 40 to form an image on the recording paper after the necessary image processing has been performed by the respective units 11 (S8). As a result, the recording unit 40 forms an image on the recording paper with the image data in which the digital watermark information indicating the halftone dot information used for the halftone dot formation processing for the image data to be image-formed is embedded. Therefore, even when the recording paper on which image formation has been performed by the multifunction device 1 is further copied by the multifunction device 1, it is possible to perform halftone dot reproduction based on the above-described digital watermark information. No degradation of image quality due to generation copy occurs.

  For example, when the number of halftone lines and the halftone angle are directly detected from the pixel group constituting the original image data read by the original reading unit 5 as in the prior art, it is accurately determined according to the resolution and accuracy of the image reading. In some cases, the number of halftone dots and the halftone dot angle cannot be detected, and there are cases where the halftone dot region cannot be accurately determined based on such an inaccurate halftone line number and halftone angle. According to the series of processes described above, the region determination unit 111 can accurately determine a halftone dot region using the halftone dot identification information (number of halftone lines, halftone dot angle, etc.) indicated by the digital watermark information.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the above-described embodiment, the halftone dot information indicated by the digital watermark information is halftone dot specifying information including the number of halftone dots and the halftone dot angle, but may be only one of the number of halftone dots or the halftone dot angle. . The halftone dot information may further include information other than the number of halftone lines and / or the halftone dot angle.

  In the above-described embodiment, the multifunction device 1 is described as performing digital watermark information extraction, halftone dot area determination, and halftone dot reproduction processing on the original image data read by the original reading unit 5. However, for example, when the multifunction device 1 functions as a printer or a facsimile machine, a network I / F is connected from an external personal computer connected via a network or an external facsimile machine connected via a public line. With respect to the image data to be subjected to image formation acquired by the unit 9, the digital watermark information extraction, halftone dot region determination, and halftone dot reproduction processing described in the above embodiment may be performed. In this case, the network I / F unit 9 functions as an image data acquisition unit in the claims. For example, when a document A on which an image in which digital watermark information is embedded is formed is scanned and stored in a personal computer as a file including image data a such as jpeg, the image data a is combined from the personal computer. When the image is transmitted to the machine 1 and printed out, the multifunction machine 1 or the like uses the extraction of the digital watermark information, the determination of the halftone area, and the halftone dot reproduction process described in the above embodiment to obtain a halftone dot in the image data. It can be accurately reproduced in the same manner as the halftone dots of the image on the original A.

1 is a cross-sectional view schematically showing an internal configuration of a multifunction machine 1 as an example of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a functional block diagram illustrating a schematic configuration of the multifunction peripheral illustrated in FIG. 1. (A) is a diagram schematically showing how digital watermark information is extracted from a document image, and (b) is a diagram schematically showing how digital watermark information is combined with an image to be output to recording paper. It is. 5 is a flowchart illustrating processing for area determination and image formation during a copying operation of a multifunction peripheral.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multifunction machine 5 Original reading part 51 Scanner part 81 Halftone information storage part 9 Network I / F part 10 Control part 11 Image processing part 111 Area determination part 112 Digital watermark information extraction part 113 Digital watermark information generation part 114 Image processing according to area Unit 115 filter processing unit 40 recording unit

Claims (4)

An image data acquisition unit for acquiring image data to be subjected to image formation;
A digital watermark information extraction unit that extracts digital watermark information embedded in the image data acquired by the image data acquisition unit;
A region determination unit that determines a halftone dot region from the image data acquired by the image data acquisition unit using the halftone dot information indicated by the digital watermark information extracted by the digital watermark information extraction unit;
An image processing unit for each region that performs image processing predetermined for each region on the image data of each region determined by the region determination unit;
An image forming unit that forms an image on an image forming medium, the image data obtained by the image data obtaining unit and subjected to the image processing by the image processing unit for each area ,
The halftone dot information indicated by the digital watermark information is an halftone dot type specifying information for specifying a halftone dot type including at least one of the number of halftone lines and the halftone dot angle . A digital watermark information generating unit that generates digital watermark information indicating halftone dot information used in the halftone dot forming process for the halftone dot region by the image processing unit for each region;
The image forming apparatus according to claim 1 , wherein the image processing unit for each region embeds digital watermark information generated by the digital watermark information generation unit in image data determined to be a halftone dot region by the region determination unit . An image data acquisition unit for acquiring image data to be subjected to image formation;
A digital watermark information extraction unit that extracts digital watermark information embedded in the image data acquired by the image data acquisition unit;
An area determination unit for determining a halftone dot area from the image data acquired by the image data acquisition unit using the halftone dot information indicated by the digital watermark information extracted by the digital watermark information extraction unit;
Dot information representing said electronic watermark information, the image processing apparatus is a dot type specifying information for specifying the halftone dot type including at least one screen ruling or dot angle. An image processing program for causing a computer to perform image processing,
A digital watermark information extraction unit that extracts digital watermark information embedded in the image data acquired by the image data acquisition unit;
A computer including a region determination unit that determines a halftone region from the image data acquired by the image data acquisition unit using the halftone dot information indicated by the digital watermark information extracted by the digital watermark information extraction unit; Function
The dot information indicated by electronic watermark information, dot type identification information der Ru image processing program for specifying the halftone dot type including at least one screen ruling or dot angle.

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