JP4995772B2 - Image reproduction system and method - Google Patents

Description

  The present invention relates to an image reproduction system and method for performing color processing on an image, outputting the image to an image forming apparatus, and forming the image on an output medium.

  Conventionally, image reproduction in which an image output from an image input device such as a digital camera is subjected to color processing by DLP (Device Link Profile) to form an image on an output medium (paper or display) of the image forming device. A system is known (Patent Document 1).

  In the image reproduction system according to the prior art disclosed in Patent Document 1 and the like, the same image is divided into a plurality of regions, and an appropriate input profile is selected for each divided region, and device-independent image data is respectively obtained. Is converted to device-dependent image data of the image forming apparatus by an output profile corresponding to the image forming apparatus, and an image is formed (reproduced) on the output medium of the image forming apparatus. )

  DLP is a concept that combines an input profile (device-dependent data → device-independent data) and an output profile (device-independent data → device-dependent data).

  Also, a scene analysis technique is known (Patent Document 2). For scene analysis, for example, flash shooting detection, human face area extraction, blue sky detection, ground detection, etc. can be used, and flash shooting detection includes, for example, the degree of under, average density, dynamic range, and RGB values. Whether or not the flash photography is performed is estimated from the maximum value and the minimum value. By using such scene analysis, for example, it is possible to limit the correction target to a human face area. When the target area is limited by pre-processing, the processing time can be significantly reduced and mounting on lab equipment becomes easy.

JP 2000-341499 A (FIG. 1) JP 2004-139574 A (paragraph [0012])

  By the way, as shown in the diagram on the left side of FIG. 7, when color processing is performed on a page P (printed material) on which a photograph image 8, a photograph image 10, and a document (document data such as text data) 12 are present. Once converted into PDL (page description data). In this case, as shown in the center diagram of FIG. 7, the rectangular image 8 is divided into rectangular strip-shaped divided images 8a, 8b, and 8c. Further, a rectangular image 10 close to a rhombus is divided into rectangular strip-shaped divided images 10a, 10b, and 10c.

  According to the prior art, since different color processing is performed for each of the divided images 8a, 8b, 8c, 10a, 10b, and 10c, the image of the page P of the color processing result shown in the right diagram of FIG. 8 has a problem that the divided images 8a, 8b, and 8c have different colors, and the image 10 also has a problem that the divided images 10a, 10b, and 10c have different colors.

  In this way, the images 8 and 10 are divided into the divided images 8a, 8b, 8c, respectively, despite being originally the same image 8 (for example, portrait of a person) and 10 (for example, a yacht floating in the sea). When color processing is performed with different profiles for each of 10a, 10b, and 10c, the color processing results of the image 8 and the image 10 formed on the output medium of the image forming apparatus are sparse. However, there is a problem that desired color reproduction is not performed.

  In addition, in the rectangular image 10 close to the rhombus, the image 10 is divided into strip-shaped divided images 10a, 10b, and 10c. Therefore, when color processing is performed, portions that do not originally have an image (divided images 10a, 10b). 10c is a pixel value that is not hatched, for example, as a pixel value “0”, and color processing is greatly shifted.

  The present invention has been made in consideration of such problems, and provides an image reproduction system and method capable of performing desired color reproduction even when performing color processing by dividing an image. With the goal.

  In this specification, “page” refers to one page (one leaf) of a book page or printed matter.

  An image reproduction system according to the present invention has the following characteristics (1) to (4) in an image reproduction system that performs color processing on an image and forms the image on an output medium.

(1) The same image for determining whether or not the divided images are originally the same image based on the pixel values of the boundary pixels between the adjacent divided regions and the region dividing unit that divides the image into a plurality of regions The image processing apparatus includes a determination unit and a color processing unit that performs the same color processing on the determined identical image.

  According to the invention having the above feature (1), after the image is divided into a plurality of regions by the region dividing unit, it is determined whether the divided images are originally the same image by the same image determining unit. Discrimination is made based on the pixel values of the boundary pixels between the regions, and the same color processing is performed by the color processing unit on the originally determined same image, so that desired color reproduction is originally performed on the same image. It can be performed.

(2) In the invention having the above feature (1), the same image determination unit determines whether or not the divided images are originally the same image based on the continuity of the image in the frequency domain. It is characterized by that.

  If the pixel values of the boundary pixels between adjacent divided regions are originally the same image boundary, the frequency of the pattern approximates, so it can be easily confirmed whether the images are originally the same image.

(3) In the invention having the above feature (1), the same image determination unit determines whether or not the divided images are originally the same image based on the continuity of the noise pattern of the image. And

  For example, the noise pattern of an image captured by a solid-state camera such as a CCD camera is unique to each solid-state camera, and the noise pattern changes when the ambient temperature changes. Moreover, since this noise pattern has a high frequency compared with the frequency of the pattern, for example, a noise component is extracted by a high-pass filter (high-pass filter), and by checking the pattern, the divided image is originally the same image. It is possible to easily determine whether the image is a divided image.

(4) In the invention having any one of the above characteristics (1) to (3), the color processing unit is characterized in that a pixel having no pixel value is not subjected to color processing.

  For example, on the divided image divided into strips, the pixel value of a place where the image does not exist (transparent place) is changed to an impossible pixel value (such as “−1” when the pixel value is 0 to 255). Set.

  In this way, by not using pixels that do not have pixel values as a target of color processing, it is possible to perform appropriate color processing only on the image portion in the divided image.

  An image reproduction method according to the present invention is an image reproduction method for performing color processing on an image and forming the image on an output medium, and an area division process for dividing the image into a plurality of areas, and adjacent divided areas The same image determination process for determining whether or not the divided images are originally the same image based on the pixel values of the mutual boundary pixels, and the color processing process for performing the same color processing on the determined same image It is characterized by having.

  According to the present invention, after an image is divided into a plurality of regions, it is determined whether or not the divided images are originally the same image based on the pixel values of the boundary pixels between adjacent divided regions. In addition, since the same color processing is performed on the originally same image by the color processing unit, desired color reproduction can be performed on the originally same image.

  An image reproduction system that implements the image reproduction method of the present invention will be described below with reference to the drawings. In the drawings to be referred to below, the same reference numerals are assigned to the components corresponding to those shown in FIG. 7 and the detailed description thereof is omitted.

  FIG. 1 is a configuration diagram of an image reproduction system 20 according to this embodiment. The image reproduction system 20 basically includes a DTP (Desk Top Publishing) device 22 in which software used when an operator edits characters and images is installed. An input device 24 for inputting a document, a color processing device 26 for performing color processing on a page (page data) P output from the DTP device 22, and a page (page data) P after the color processing for a raster image (raster An RIP (Raster Image Processor) 28 for converting the image data) and an image forming apparatus 30 for forming an image or a document on the output medium 6 based on the raster image.

  As the image forming apparatus 30, an ink jet printer, an electrophotographic machine, a DDCP (Direct Digital Color Proof) apparatus, or the like is used. The concept of the image forming apparatus 30 may include an image display (display).

  The input device 24 includes a digital camera 32 that outputs a color image (image data) 8, a scanner 34 that outputs a color image (image data) 10, or a word processor 36 that outputs a document (document data such as text data) 12. Etc.

  The DTP device 22 in which software used for editing characters and images is installed and the color processing device 26 are each constituted by a personal computer or the like.

  The DTP device 22 assigns the image 8, the image 10, and the document 12 to the page P and outputs them to the color processing device 26.

  The color processing device 26 also operates as a function realization unit (function realization means) that realizes various functions when the CPU executes programs stored in a memory such as a ROM based on various inputs. In this embodiment, the color processing device 26 is an area dividing unit 52 that divides an image into a plurality of areas, and a divided area in which the same image is divided based on pixel values of boundary pixels between adjacent divided areas. The same image discriminating unit 54 for discriminating whether there is a color, the color processing unit 56 for performing the same color processing on the divided areas obtained by dividing the same image, and the synthesizing unit 58 for synthesizing the pages after color processing. Have.

  Details of the color processing device 26 will be described later.

  The image forming apparatus 30 corresponds to the page Pa based on the raster image by the RIP 28 of the page Pa that has been subjected to the color processing by the color processing apparatus 26 with respect to the page P input to the DTP apparatus 22, and the images 8 and 10 and the document. 12 outputs, for example, a printed hard copy HC (printed material) formed on the output medium 6.

  Next, the operation of the color processing device 26 will be described with reference to the flowchart of FIG.

  In step S1, the area dividing unit 52 of the color processing device 26 converts the page P of the image 8, the image 10, and the document 12 sent from the DTP device 22 into page description data (Page) as shown in FIG. (Description Language).

  In this case, the image 8 and the image 10 are each divided into strip-shaped (rectangular) divided images 8a, 8b, 8c, 10a, 10b, and 10c. Note that each of the divided images 10a, 10b, and 10c includes an image portion indicated by hatching and a transparent portion without hatching. The divided images 8a, 8b, and 8c of the originally rectangular image 8 do not include a transparent portion. Note that the document 12 is not targeted for division.

  In step S2, the same image discriminating unit 54 of the color processing device 26 divides adjacent divided regions (divided image 8c and divided image 8b, divided image 8b and divided image 8a, divided image 10c and divided image 10b, and divided image 10b and divided. Based on the pixel values of the mutual boundary pixels of the image 10a), it is determined whether or not the same image is a divided region.

  In this case, as shown in FIG. 4 schematically showing the pixels by circles, the divided pixel 8c existing in the image 8 and the boundary pixel Px1 and the boundary pixel Px2 adjacent to the divided image 8b have the same pixel value. Therefore, it can be determined that the divided images 8c and 8b are the divided areas in which the same image 8 is originally divided. Similarly, the boundary image Px3 and the boundary pixel Px4 that are adjacent to each other in the divided image 8b and the divided image 8a have the same or close pixel values, and thus are determined to be the divided images 8b and 8a in the divided region where the same image 8 was originally divided. can do. Therefore, the divided images 8a, 8b, and 8c can be determined as the same image 8 by the same image determining unit 54.

  Similarly, the pixel values of the adjacent pixel Px5 and the adjacent pixel Px6 of the divided image 10c and the divided image 10b existing in the image 10 of FIG. Since they are close to each other, it can be determined that they are the divided images 10c and 10b in the divided area where the same image 10 was originally divided. Similarly, the boundary image Px7 and the boundary pixel Px8 adjacent to each other in the divided image 10b and the divided image 10a are the same or close to each other, and thus are determined to be the divided images 10b and 10a in the divided region where the same image 10 was originally divided. can do. Therefore, it is possible to determine that the divided images 10a, 10b, and 10c are originally the same image 10. However, since the pixels marked with ● in the transparent portion originally have no image, the pixel value is set to an impossible pixel value such as −1. The same image is not discriminated for the boundary pixel having the pixel value = −1.

  When determining whether or not they are the same image, as shown in FIG. 5, the function of the pixel value of the boundary line to which the boundary pixel Px1 belongs is a function z = f (x, y), and the function of the boundary line to which the boundary pixel Px2 belongs. When the function of the pixel value is set as function z = g (x, y), the function value f (x2, y2) of the position x2 and y2 of the boundary pixel Px2 and the function value of the position x2 and y2 + 1 of the boundary pixel Px1 When g (x2, y2 + 1) is approximate or equal, it can be determined that they are the same image 8.

  In other words, when the images 8 and 10 have continuity in the frequency domain, it can be determined that the same images 8 and 10 are divided images.

  The image 8 includes specific high-frequency noise (high-frequency noise exceeding the upper limit of the frequency of the picture) due to the CCD image pickup device built in the digital camera 32, and the image 10 is a CCD image pickup built in the scanner 34. Since it contains high frequency noise peculiar to the element (high frequency noise exceeding the upper limit of the frequency of the picture), adjacent divided images (8c and 8b, 8b and 8a) and adjacent divided images (10c and 10b, 10b and 10a) are included. )), It is possible to determine whether or not the images are the same images 8 and 10 by comparing the noise distribution of the boundary line composed of adjacent pixels. Since this noise distribution is different even if the ambient temperature is different, it is possible to accurately determine whether or not the images are originally the same.

  Note that the boundary pixels may be compared by thinning (compressed) when the resolution of the image is high. As long as the frequency of the pattern remains even after thinning and comparing, and as long as there is a high-frequency noise peculiar to the CCD image sensor, it is difficult to determine whether adjacent divided images are originally the same image. There is no.

  Next, in step S <b> 3, before the page P is synthesized, the color processing unit 56 performs color processing for each of the determined identical images 8 and identical images 10.

  Note that it is preferable to perform scene analysis or the like in advance before performing color processing. At the time of this scene analysis, the pixel value of the pixel of the transparent portion in the image 10 (the portion of the strip-shaped divided images 10a, 10b, and 10c that is not an image without hatching) is “−1” or the like. Appropriate scene analysis can be performed by using unrecognized values. If “0” is used instead of the value “−1”, it is recognized as white, so that appropriate scene analysis cannot be performed. Since scene analysis is disclosed in Patent Document 2 and the like and is well known, it will be omitted.

  Since the color processing is also well known as disclosed in Patent Document 1 and the like, a brief description will be given. Input profiles (device-dependent data) created in advance for the image 8 of the digital camera 32 and the image 10 of the scanner 34, respectively. Image 8 and image 9 by each DLP that links the output profile (converter from device-independent data to device-dependent data) generated in advance with respect to the image forming apparatus 30. Can be color processed.

  The page (page data) Pa including the images 8 and 10 and the document 12 subjected to the color processing and synthesized by the synthesis unit 58 of the color processing device 26 is supplied to the RIP 28.

  The page Pa supplied to the RIP 28 is converted into a raster image and supplied to the image forming apparatus 30. The image 8 and the image 8 are subjected to the same color processing for each of the images 8 and 10 on the output medium 6 from the image forming apparatus 30. A hard copy HC representing page Pa on which 10 and document 12 are printed is output.

  As described above, according to the above-described embodiment, the area dividing unit 52 converts the image 8 and the image 10 of the page P including the plurality of images 8 and 10 into the divided images 8a, 8b, 8c including the plurality of areas. After being divided into divided images 10a, 10b, and 10c, the same image discriminating unit 54 uses the same image discriminating unit 54 as pixels of boundary pixels between the divided images (8c and 8b, 8b and 8a, 10c and 10b, and 10b and 10a) in adjacent divided regions. Based on the value, it is determined whether or not the divided images are originally the same image, and the same color processing is performed by the color processing unit 56 on the originally determined images 8 and 10. Even when different images 8 and 10 are arranged in the page P, desired color reproduction can be performed on the images 8 and 10.

  More specifically, FIG. 6 (example) and FIG. 7 (prior art: PRIOR ART) will be described. In the prior art shown in FIG. 7, each of the divided images 8c, 8b, 8a, 10c, 10b, 10a. For example, in the embodiment shown in FIG. 6, there is a problem that the color of the image differs between the divided image 8 a of the image 8 and the remaining divided image 8 b. Since scene analysis and color processing are performed for each of the same images 8 and 10, desired color processing can be performed for each of the images 8 and 10.

  In this case, the same image discriminating unit 54 discriminates whether or not the divided images are originally the same image based on the continuity of the images 8 and 10 in the frequency domain. If the pixel values of the boundary pixels between adjacent divided regions are originally the boundaries of the same images 8 and 10, the frequency of the pattern approximates, so it is easy to determine whether or not they are the same images 8 and 10 originally. Can be confirmed.

  Further, the same image determination unit 54 determines whether or not the divided images are originally the same images 8 and 10 based on the continuity of the noise patterns of the images 8 and 10. For example, the noise pattern of an image captured by a digital camera 32 that is a solid-state camera such as a CCD camera is unique to each digital camera 32, and the noise pattern changes when the ambient temperature changes. In addition, since this noise pattern is higher in frequency than the pattern frequency, for example, a noise component is extracted by, for example, a high-pass filter (high-pass filter), and the same image 8, 10 is originally divided by checking the pattern. It is possible to easily determine whether the divided image has been obtained.

  Note that the color processing unit 56 does not set pixels for which no pixel value exists as a target for color processing. For example, the pixel value of a place where the image 10 does not exist (the area having no hatching in the strip-shaped divided images 10a, 10b, and 10c in FIG. 3) is assumed to be an impossible pixel value (when the pixel value is 0 to 255). , -1 etc.). In this way, by not using pixels that do not have pixel values as a target of color processing, it is possible to perform appropriate color processing only on the image portion in the divided image.

  Note that the present invention is not limited to the above-described embodiment, and can be applied to the case where only one image exists in the page P (for example, only the image 10 in the page P). Of course, various configurations can be adopted based on the contents.

It is a block diagram of the image reproduction system which concerns on this embodiment. It is a flowchart with which operation | movement description of a color processing apparatus is provided. It is explanatory drawing of area division (division image). It is explanatory drawing of the discrimination | determination process of the same image originally based on the pixel value of a boundary pixel. It is explanatory drawing of the discrimination | determination process of the same image originally based on the continuity of the frequency of a pattern. It is a schematic diagram of the color processing of an Example. It is a schematic diagram of the color processing of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Image reproduction system 22 ... DTP apparatus 24 ... Input device 26 ... Color processing apparatus 28 ... RIP 30 ... Image forming apparatus 52 ... Area division part 54 ... Same image discrimination | determination part 56 ... Color processing part

Claims (6)

In an image reproduction system that performs color processing on an image and forms the image on an output medium,
An area dividing unit for dividing the image into a plurality of areas;
The same image discriminating unit for discriminating whether or not the divided images are originally the same image based on the pixel values of the boundary pixels between the adjacent divided regions;
A color processing unit that performs the same color processing on the originally identified same image;
An image reproduction system characterized by comprising: The image reproduction system according to claim 1,
The same image discrimination unit
The pixel values of the pixels on the boundary line between adjacent divided regions are represented by two types of functions each having the position of each pixel as an argument,
It is determined whether or not the divided images are originally the same image based on the closeness of the pixel values of the boundary pixels calculated using the two types of functions.
An image reproduction system characterized by that. The image reproduction system according to claim 1 or 2 ,
The same image discrimination unit
An image reproduction system characterized by determining whether or not the divided images are originally the same image based on the continuity of the image in the frequency domain. The image reproduction system according to any one of claims 1 to 3 ,
The same image discrimination unit
An image reproduction system characterized by determining whether or not the divided images are originally the same image based on the continuity of the noise pattern of the image. In the image reproduction system according to any one of claims 1 to 4 ,
The color processing unit
An image reproduction system characterized in that pixels that do not have pixel values are not subject to color processing. In an image reproduction method for performing color processing on an image and forming the image on an output medium,
A region dividing process for dividing the image into a plurality of regions;
The same image discrimination process for discriminating whether or not the divided images are originally the same image based on the pixel values of the boundary pixels between adjacent divided regions;
A color processing process for performing the same color processing on the originally identified same image;
An image reproduction method characterized by comprising:

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