JP2009302671A - Image processing method, image processing apparatus, and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing method for applying processing relating to addition of dots with respect to compressed image data, while being left compressed, as it is. <P>SOLUTION: An image processor specifies a pixel at a position, corresponding to a dot to be embedded for each block with respect to image data compressed to an index, showing a region to which the pixel belongs to for each pixel and color information regarding the region by the block unit (S307). The image processor overwrites the index so that the region to which a predetermined pixel belongs becomes a region corresponding to the dot (S311). Moreover, the image processor designates the color information on the region, corresponding to the dot so that the color information becomes the color corresponding to the dot (S313). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image processing method, an image processing apparatus, and an image processing program, and more particularly to an image processing method, an image processing apparatus, and an image processing program for performing image processing on compressed image data.

In an image processing apparatus such as an MFP (Multi Function Peripheral), image processing for adding information to image data is performed by various methods. Specific contents of the image processing include processing of converting watermark characters or information into dots and embedding the dots in the image data. In Japanese Patent Laid-Open No. 2006-324909 (hereinafter referred to as Patent Document 1), the applicant of the present application discloses a method of embedding information in image data with dots and a method of detecting information embedded in image data. Various methods have been proposed for compressing image data in which dots are embedded. For example, Japanese Unexamined Patent Application Publication No. 2007-97130 (hereinafter referred to as Patent Document 2) discloses a technique for changing the compression method depending on whether or not the copy-forgery-inhibited pattern image data is included in the image data. Japanese Unexamined Patent Application Publication No. 2007-166227 (hereinafter referred to as Patent Document 3) discloses a technique for separating control information and original image data embedded from image data and compressing only the original image data.
JP 2006-324909 A JP 2007-97130 A JP 2007-166227 A

  By the way, in an image processing apparatus, image data may be compressed and stored. When adding dots to compressed image data, adding dots after processing to return the compressed image data to the state before compression requires a lot of memory for the processing. is there.

  The present invention has been made in view of such a problem, and an image processing method, an image processing apparatus, and an image processing method capable of performing processing relating to dot addition in a compressed state with respect to compressed image data, and An object is to provide an image processing program.

  In order to achieve the above object, according to one aspect of the present invention, an image processing method is an image processing method for compressed image data, and the compressed image data is associated with each pixel. A specific step that includes information indicating the representative color and specifies the pixel corresponding to the dot position in the image data, and rewrites the correspondence of the representative color to the pixel corresponding to the dot position in the compressed image data A rewriting step.

  Preferably, the compressed image data is configured to include the information in units of blocks, and the specifying step and the rewriting step execute processing for each number of pixels of the compressed image data according to the number of pixels of the block. To do.

  More preferably, the unit of processing for the compressed image data in the specifying step and the rewriting step is a divisor pixel number excluding 1 of the block pixel number.

  Preferably, the information indicating the representative color included in the compressed image data includes an area for storing information indicating the color corresponding to the dot.

  Preferably, the compressed image data includes, for each pixel, information specifying a representative color associated with the pixel and information indicating the representative color, and the rewriting step is performed for the pixel corresponding to the dot position. The information specifying the representative color associated with the pixel is rewritten.

  Preferably, the compressed image data includes, for each pixel, information specifying a representative color associated with the pixel and information indicating the representative color, and the rewriting step rewrites information indicating the representative color.

  Preferably, the image processing method is an image processing method for embedding embedded data in compressed image data, further comprising a step of inputting embedded data and a step of converting the embedded data into dots. In the rewriting step, the correspondence relationship of the representative color with respect to the pixel corresponding to the dot position in the compressed image data is rewritten so as to be associated with the representative color corresponding to the dot.

  Preferably, the image processing method is an image processing method for removing dots from compressed image data to which dots are added, and the rewriting step corresponds to a dot position in the compressed image data. The correspondence relationship of the representative color with respect to the pixel is rewritten so as to be associated with the representative color corresponding to the representative color associated with the pixel adjacent to the pixel corresponding to the dot position.

  According to another aspect of the present invention, an image processing apparatus includes an acquisition unit that acquires compressed image data, and an image processing unit that performs image processing on the compressed image data. Is configured to include information indicating the representative color associated with each pixel, and the image processing means includes a specifying step of specifying a pixel corresponding to a dot position in the image data, and the compressed image data Then, an image processing is performed, which includes a rewriting step of rewriting the correspondence relationship of the representative color with respect to the pixel corresponding to the dot position.

  According to still another aspect of the present invention, an image processing program is a program for causing a computer to perform image processing on compressed image data, and the compressed image data is associated with each pixel. A specific step of specifying a pixel corresponding to the dot position in the image data, and a correspondence relationship of the representative color with respect to the pixel corresponding to the dot position of the compressed image data. The computer executes the rewriting step for rewriting.

  According to the present invention, it is possible to add dots to a compressed image data in a compressed state. Further, it is possible to remove the dots in the compressed state from the compressed image data to which the dots are added.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

  In the present embodiment, the image processing apparatus according to the present invention will be described as being realized in a personal computer (hereinafter, PC).

  FIG. 1 is a diagram illustrating a specific example of a configuration concept of the PC 1 and its peripheral devices according to the present embodiment that function as an image processing apparatus. Referring to FIG. 1, a PC 1 includes a mouse 11 and a keyboard 12 as operation input means, a monitor 13 as an image output means, a printer 15 as an image forming apparatus, a scanner 16 as an image reading means, and a storage. It is connected to an external storage device 14 which is one of the means. The PC 1 includes an input / output interface (I / F) 100 therein, and exchanges information with these connected peripheral devices. Further, the PC 1 includes a CPU (Central Processing Unit) 101 that is a calculation means and a storage device 102 that is one of the storage means. Image processing software is stored in the storage device 102. The CPU 101 reads out and executes the image processing software, so that the PC 1 functions as the image processing device according to the present invention.

  The apparatus for realizing the image processing apparatus according to the present invention is not limited to a PC, and may be other apparatuses. A typical example of the other apparatus is an image forming apparatus such as an MFP (Multi Function Peripheral). FIG. 2 is a diagram showing a specific example of a configuration concept of MFP 2 functioning as an image processing apparatus when the image processing apparatus according to the present invention is realized by an MFP as another example. Referring to FIG. 2, MFP 2 includes an operation panel unit 21 that is an operation input unit, a scanner unit 22 that is an image reading unit, and a printer unit 23 that is an image output unit. Further, the MFP 2 includes an image processing unit 201 therein. When the image processing unit 201 executes the process, the MFP 2 functions as the image processing apparatus according to the present invention.

  FIG. 3 is a block diagram showing a specific example of the hardware configuration and functions of the PC 1 according to the present embodiment. Referring to FIG. 3, as described above, the PC 1 includes an input / output I / F 100, a CPU 101, and a storage device 102 therein.

  The input / output I / F 100 is connected to the mouse 11 and the keyboard 12 and receives user instructions input from the mouse 11 and / or the keyboard 12. Further, it is connected to the monitor 13 and passes display image data to the monitor 13. Further, it is connected to the scanner 16 and receives a scan image (scan data) obtained by scanning with the scanner 16. Further, the printer 15 is connected to the printer 15 and passes image data for printing to the printer 15.

  The storage device 102 stores the above-described image processing software and operation software. At least a part of these software may be stored in the external storage device 14. The CPU 101 includes a memory therein, and executes the software read from the storage device 102 while expanding it in the internal memory. At this time, data input via the input / output I / F 100 is used, or data generated by the processing is output to another device via the input / output I / F 100.

  An image processing apparatus realized by the CPU 101 executing image processing software stored in the storage device 102 is created by executing image data obtained by reading a document image with the scanner 16 or application software in the PC 1. For image data such as image data (for example, document data created by execution of document creation software), the input data is converted into a predetermined dot pattern, and dots are embedded. Further, the original image data is restored by separating dots from the image data obtained by scanning the image thus generated.

  In the following description, an image before dots are embedded is referred to as a “document image”. Data indicating information to be embedded in the document image is referred to as “embedded data”.

  FIG. 4 is a block diagram showing a specific example of a functional configuration of the PC 1 when embedding data is embedded in a document image. Each function illustrated in FIG. 4 is a function configured in the CPU 101 mainly by the CPU 101 executing image processing software stored in the storage device 102. Further, it may be realized using the hardware configuration shown in FIG.

  Referring to FIG. 4, the functions of PC 1 are as follows: document image data input unit 301, compression unit 302, representative value calculation unit 303, image storage unit 304, embedded data input unit 305, conversion unit 306, and composition processing unit 307. A reading unit 308 and a pattern storage unit 309.

  The document image data input unit 301 is connected to the input / output I / F 100 and receives document image data input via the input / output I / F 100 after the scanner 16 scans the document image. Alternatively, the document image data input unit 301 includes execution means such as application software in the PC 1 (not shown), and acquires image data created by executing the application software. The document image data input unit 301 is further connected to the dividing unit 302 and outputs the input document image data to the compression unit 302. The compression unit 302 performs a compression process on the document image data. The compression unit 302 includes a representative value calculation unit 303, and calculates a representative value to be described later during the compression process. The compression unit 302 is further connected to the image storage unit 304, and outputs and stores the compressed document image data (hereinafter referred to as compressed data) together with the calculated representative value and the image storage unit 304. A reading unit 308 is connected to the image storage unit 304, and the specified compressed data is read from the image storage unit 304 by the reading unit 308 and input to the synthesis processing unit 307.

  The embedded data input unit 305 is connected to the input / output I / F 100 and receives embedded data input through the input / output I / F 100 when the mouse 11 or the keyboard 12 is operated. The embedded data input unit 305 is further connected to the converting unit 306 and outputs the input embedded data to the converting unit 306. The pattern storage unit 309 stores an additional pattern, which is a basic dot pattern, for adding dots to the compressed data. The conversion unit 306 is connected to the pattern storage unit 309 and converts the embedded data into the arrangement of the additional pattern with reference to the stored additional pattern. The conversion unit 306 is further connected to the synthesis processing unit 307 and inputs the converted result to the synthesis processing unit 307. The synthesis processing unit 307 refers to the additional pattern stored in the pattern storage unit 309 based on the input conversion result, and fills the compressed data input from the reading unit 308 with dots. Execute processing to synthesize embedded data.

  FIG. 5 is a flowchart showing a specific example of processing for embedding embedded data in a document image in the PC 1. The flowchart in FIG. 5 is realized by the CPU 101 executing image processing software stored in the storage device 102.

  Referring to FIG. 5, in step S <b> 10, embedded data input unit 305 receives input of embedded data from mouse 11, keyboard 12, or the like via input / output I / F 100. The embedding data input in step S10 is subjected to conversion processing in the conversion unit 306 in step S20.

  In step S30, the reading unit 308 reads the designated compressed data from the image storage unit 304. In step S40, the composition processing unit 307 executes composition processing for adding the dots converted in step S20 to the compressed data read in step S30.

  Prior to the description of the process of adding dots to the compressed data in step S40, the process of generating compressed data by compressing document image data in the compression unit 302 will be described. The compression method of the image data in the compression unit 302 is not limited to a specific method in the present invention. In the present embodiment, a compression method called BTC (Block Truncation Coding) compression is adopted. BTC compression is a compression method in which document image data is divided into a plurality of areas, and all pixels in each area are represented by one representative color. As a result, the number of colors in the area is reduced, and the amount of data is reduced. The color value of the representative color is referred to as “representative value”.

  Specifically, referring to FIG. 6, in step S101, compression unit 302 divides document image data into blocks of a predetermined size. After initializing the variable n (step S103), the variable n is incremented by 1 (step S105), and the first area dividing process is executed for the block corresponding to the variable n in step S107. In step S109, a second area division process is further executed on the image data after the division in step S107. Thereafter, in step S111, the representative value calculation unit 303 calculates the above-described representative value for each area of the block. In step S113, the compression unit 302 designates a representative color as a palette color corresponding to the area, out of palette colors that are color information in the block, and outputs data related to the block in step S115. The compression unit 302 performs the above processing for each block until the number N of blocks divided in step S101 is reached (YES in step S117).

  The above compression method will be described with a specific example of document image data. FIG. 7A is a diagram showing a specific example of one block obtained by dividing the document image data into a predetermined size (here, 8 × 8 pixels). Specifically, the block has a second gradation in the vertical direction at a substantially central portion of a gradation in which the density of the first color (for example, red) increases diagonally from the upper left to the lower right of the rectangular document. It is assumed that the image data is a color (for example, blue) region overlapped. It is assumed that the block in FIG. 7A is used for the processing in steps S107 to S113.

As a specific example of the first area dividing process in step S107, the compression unit 302 displays C (cyan), M (magenta), Y (yellow), and K that indicate each pixel in the block of FIG. (Black) For the image data of each color, the color value variation in the block is detected, and the image data of the color having the largest color value variation is specified. Further, for the specified image data, an average value of the color values of the pixels in the block is calculated and divided into an area having a color value larger than the average value and an area having a smaller color value. FIG. 7B shows a state after the first area dividing process is performed on the block of FIG. By performing the first region dividing process described above, the region to which the second color is applied is divided into the region 0 and the region to which the first color is applied is divided into the region 1. The second area dividing process is similarly performed in step S109 on the block in the state of FIG. 7B after the first area dividing process is performed. That is, for each of the areas 0 and 1, similarly, variations in color values are detected for the C, M, Y, and K color image data. The image data of a color with a large variation in the number is specified. Then, as with the first region dividing process, the compression unit 302 divides the image data of the color having the largest color value variation into a region having a color value larger than the average value in the region and a region having a smaller color value. . FIG. 7C shows a compressed block after the second area division processing is further performed on the block in the state of FIG. 7B. In this example, the region 1 in which the first color forms a gradation is further divided into a region 1 that is a lighter side region and a region 2 that is a darker region. In step S111, the representative value calculation unit 303 calculates the color values represented by the palette numbers 00, 01, and 10, respectively, as the average value of the color values as the representative value of each region. Here, as described above, when the first color is red and the second color is blue, the colors of the palette numbers 00, 01, and 10 which are the representative colors of the area 0, the area 1, and the area 2 are used. The values are specifically expressed as C (cyan), M (magenta), Y (yellow), and K (black) values as follows:
Pallet number 00: (C, M, Y, K) = (235, 217, 8, 28),
Pallet number 01: (C, M, Y, K) = (3, 31, 13, 3),
Pallet number 10: (C, M, Y, K) = (8, 115, 64, 5).

Here, as described above, the region division processing is performed twice for one block. Therefore, information of four colors corresponding to the palette numbers 00, 01, 10, and 11 is stored in the palette color that is color information relating to the block of FIG. 7A, and the compression unit 302 in FIG. Four colors are designated as the palette colors of the block A). In other words, when the number of area division processes is m, the compression unit 302 designates 2 ^m colors as palette colors. At this time, the compression unit 302 uses the calculated representative values for three of the four colors, and does not specify a specific color value for the fourth color corresponding to the palette number 11. The fourth color corresponds to a representative color of the region 3, which is a pixel at a position where a dot is added, that is, a dot color, which will be described later.

  FIG. 8 is a diagram showing a specific example of the data structure of the compressed data for one block output to the image storage unit 304 in step S115. Referring to FIG. 8, the compressed data is composed of information indicating the representative colors of areas 0 to 3 corresponding to palette numbers 00 to 11, which are the above palette colors, and indexes for each block. . The index is composed of information indicating to which region each of the 64 pixels constituting the block belongs.

  If the color value is represented by 8 bits each of the above-mentioned C, M, Y, and K values, the data amount of color information for one color is 32 bits. The amount of data for one block before compression is 2048 bits because each of 64 pixels has color information. On the other hand, by performing the above-described compression processing, the total amount of color information and the amount of index data for each of the four areas is obtained. For each of the 64 pixels constituting the block, the data amount of information indicating which region belongs is 2 bits, and the data amount of the index is 128 bits. In other words, the data amount for one block of compressed data is 256 bits, which is the sum of the color information data amount (32 bits × 4 colors) and the index data amount (128 bits) for four colors. Is reduced.

[First Embodiment]
The embedding of embedded data according to the first embodiment will be described. In the first embodiment, it is assumed that a watermark image is embedded as embedded data in compressed data. FIG. 9 is a diagram illustrating a specific example of a watermark image. The watermark image shown in FIG. 9 is composed of an arrangement of dots of two types of sizes. The first dot size is 1 × 1 pixel, and the second dot size is 2 × 2 pixels. Since the dots of the former size are small, they are not printed on the printing paper during copying. Since the dot of the latter size is large, it is printed on printing paper when copied. The watermark image shown in FIG. 9 utilizes the above-described property of dot size. For example, when the original image data in which the watermark image shown in FIG. 9 is embedded is printed at a resolution of 600 dpi, and the printed original image is copied, only the large dot among the dots constituting the watermark image is printed. A vertical line emerges. FIG. 9 shows a case in which the watermark image is a vertical line. By using the above properties, a large dot is placed so that the character appears, so that the character image such as “copy prohibited” is watermarked. It can be an image.

  FIG. 10 is a flowchart showing a specific example of the embedded data conversion process in step S20 when a watermark image composed of dots as shown in FIG. 9 is embedded in a document image. FIG. 11 is a flowchart showing a specific example of the dot composition processing in step S40.

  Referring to FIG. 10, in step S <b> 201, conversion unit 306 reads an additional pattern from pattern storage unit 309. In step S203, the conversion unit 306 compares the read additional pattern with the dot arrangement of the watermark image to be embedded, and determines the arrangement of the additional pattern on the document image data.

  Referring to FIG. 11, the composition processing unit 307 that has received the arrangement of the additional pattern as a result of the above-described processing initializes the variable n in step S301 and then increments it by 1 in step S303. Then, the following processing is performed on the block corresponding to the variable n of the document image data to be processed. In step S305, the composition processing unit 307 reads the additional pattern stored in the pattern storage unit 309. In step S307, the position of the dot to be added on the processing target block is specified using the arrangement of the additional pattern as a result of the above-described processing and the additional pattern read in step S305. If there is a pixel to which a dot is added in the block (YES in step S309), in step S311, the composition processing unit 307 displays the corresponding pixel in the compressed data index of the block shown in FIG. The information indicating the area to which the image belongs is rewritten to information indicating the dot, that is, information indicating that it belongs to the area 3 in the above example. Further, in step S313, the composition processing unit 307 designates the color corresponding to the palette number 11 of the fourth color, for which the color value is not designated in step S113, as the color corresponding to the dot. Here, it is assumed that the black color value is designated, and specifically, (C, M, Y, K) = (0, 0, 0, 255) is designated. Note that if the color corresponding to the palette number 11 has already been designated among the palette colors, step S313 is skipped. The composition processing unit 307 executes the above processing for each block until the number N of blocks divided in step S101 is reached (YES in step S315).

  The above conversion process when embedding a watermark image composed of dots in a document image will be described with a specific example assuming that the watermark image shown in FIG. 9 is embedded in the document image. 12 (A) to 12 (C) are diagrams showing specific examples of additional patterns. FIG. 12 (A) shows pattern A, FIG. 12 (B) shows pattern B, and FIG. 12 (C) shows pattern C. A specific example is shown. When the conversion unit 306 reads the additional patterns of FIGS. 12A to 12C from the pattern storage unit 309 in step S201, the conversion unit 306 replaces the watermark image of FIG. 9 with the additional patterns of patterns A to C. In step S203, the arrangement of additional patterns as shown in FIG. 13 is determined.

  FIG. 14 is a diagram showing a specific example of a state where dots are added to the compressed block shown in FIG. Referring to FIG. 14, in step S307, an additional pattern is applied to the compressed document image data, whereby four pixels are specifically identified as pixels corresponding to the dots. By rewriting the index in step S311, the region to which the pixel belongs is changed to the region 3 corresponding to the dot. In step S313, the representative color of the area 3 corresponding to the palette number 11 is designated. As a result, the pixel at the specified position is replaced with the dot color, and the dot is added to the document image data as shown in FIG. In other words, the original image data in the state shown in FIG. 7C, which has been compressed by the above-described processing, is released from the compressed state without returning to the state shown in FIG. 7A. ), Dots can be embedded in the original image data as it is. That is, in the PC 1 according to the present embodiment, as described above, when the block size is 8 × 8 pixels, the data for one block compressed to 256 bits is converted into the original data size of 2048 bits. A process of embedding dots can be performed with the data size of 256 bits without decompressing the original image data and performing the process. Thereby, the amount of memory required for embedding dots can be suppressed. In addition, the processing speed can be increased.

[Second Embodiment]
The embedding of embedded data according to the second embodiment will be described. In the second embodiment, information is embedded as embedded data in compressed data. FIG. 15 is a flowchart showing a specific example of the embedded data conversion process in step S20 when information is embedded in a document image.

  Referring to FIG. 15, in step S401, conversion unit 306 reads an embedding pattern, which is a dot pattern for converting information to be embedded into dots from pattern storage unit 309, and converts the information to be embedded into dots in step S403. In step S405, the conversion unit 306 reads the additional pattern from the pattern storage unit 309. In step S407, the conversion unit 306 compares the read additional pattern with the arrangement of the embedded information dots, and determines the arrangement of the additional pattern on the document image data.

  As a specific example of the method of embedding information in the image data with dots, as described above, the method already disclosed by the applicant of the present application in Japanese Patent Laid-Open No. 2006-324909 can be employed.

  Specifically, it is assumed that the pattern storage unit 309 stores two types of embedding patterns shown in FIGS. 16A and 16B, and FIG. An embedding pattern corresponding to data 0, FIG. 16B shows a specific example of an embedding pattern corresponding to data 1 as information to be embedded. The embedding patterns in FIGS. 16A and 16B show a binarization pattern of 16 × 16 pixels. Referring to FIGS. 16A and 16B, the embedding pattern includes position expression dots D1, position expression auxiliary dots D2, and data expression dots D3. The position expression dot D1 is arranged at the upper left corner, and indicates a reference position, which is a reference position for determining the position of the data expression dot D3. The position representation auxiliary dot D2 is arranged at a position 8 pixels away from the position representation dot D1 on the right and bottom. With these dots D1 and D2, the embedding pattern is repeatedly embedded in the document image data, so that these dots are repeated on the document image at a predetermined interval. The data expression dot D3 is a dot for embedding data information, and is arranged at a position corresponding to the information to be embedded. The embedding pattern is as small as 16/600 inch (0.068 cm) per side when embedding at a resolution of 600 dpi, and appears gray when printed.

  In step S401, the composition processing unit 307 sequentially reads the embedding pattern of FIG. 16A when the information to be embedded is data 0, and the embedding pattern of FIG. FIG. 17 shows a specific example of the arrangement of the embedding pattern determined based on the information to be embedded in step S403. FIG. 18 shows a specific example of the dot pattern based on the arrangement of FIG. 17 in step S403. In steps S405 and 407, the conversion unit 306 determines the arrangement of the additional pattern based on the dot pattern shown in FIG. 18, as in the conversion process according to the first embodiment. 19A to 19C are diagrams showing specific examples of the additional pattern. FIG. 19A shows the pattern A, FIG. 19B shows the pattern B, and FIG. 19C shows the pattern C. A specific example is shown. When the conversion unit 306 reads the additional patterns in FIG. 19A to FIG. 19C from the pattern storage unit 309 in step S405, the conversion unit 306 replaces the dot patterns in FIG. In step S407, the arrangement of additional patterns as shown in FIG. 20 is determined.

  By performing the above processing with the PC 1 according to the present embodiment, information can be embedded after being converted into a dot pattern without decompressing the compressed image data.

[Third Embodiment]
In the first embodiment and the second embodiment, the size of the additional pattern is the same as the size of the block that divides the document image data. That is, in the above example, the original image data is divided into blocks with a size of 8 × 8 pixels and compressed, and dots are added to the compressed data using an additional pattern of the same size. In the third embodiment, it is assumed that dots are added using an additional pattern of a divisor size (excluding 1) of the block size.

  FIGS. 21A and 21B are diagrams showing specific examples of additional patterns used in the third embodiment. FIG. 21A shows pattern A, and FIG. A specific example is shown. Referring to FIGS. 21A and 21B, the size of the additional pattern used in the third embodiment is 4 × 4 pixels which is a divisor of 8 × 8 pixels which is the block size. is there. FIG. 22 shows a specific example of the arrangement of the additional patterns in FIGS. 21A and 21B determined based on the information to be embedded.

  As described above, since the size of the additional pattern in FIGS. 21A and 21B is 4 × 4 pixels, one block of document image data corresponds to four additional patterns. That is, in the PC 1 according to the third embodiment, as shown in FIG. 23, one block of the document image data is further divided into four equal parts, and in order according to the determined arrangement, FIG. The pixel at the position shown in the additional pattern (B) is replaced with a dot.

  As described above, by setting the size of the additional pattern to be a divisor of the size of one block into which the original image data is divided, a plurality of additional patterns can be arranged in one block of the original image data without any gaps. Can do. Further, the types of additional patterns that should be stored in the pattern storage unit 309 in advance can be suppressed.

  In the first to third embodiments described above, document image data is divided into blocks and compressed, and dots are added using an additional pattern in units of blocks. However, processing may be performed in units of an arbitrary number of pixels without performing processing in units of blocks. Moreover, you may make it add a dot to arbitrary positions, without using an addition pattern.

[Fourth Embodiment]
As a fourth embodiment, an example of a method for removing dots from compressed data to which dots have been added as described above will be described.

  When the PC 1 according to the fourth embodiment reads the compressed data to which the dots are added, the synthesis processing unit 307 corresponds to the pixels that belong to the region 3 corresponding to the dots by the index, that is, the dots. The index of the compressed data is rewritten so that the area to which the pixel to which the palette number 11 is assigned belongs is the same as the area to which the adjacent pixel belongs. That is, the color of the pixel where the dot is located is the same color as the adjacent pixel. For example, when the compressed data to which dots are added as shown in FIG. 14 is read out by the PC 1, the compositing processing unit 307 replaces the color of the pixel corresponding to the dot with the color of the pixel immediately below. 17 (C) compressed data is obtained.

  By performing the above processing with the PC 1 according to the present embodiment, it is possible to remove dots from the compressed data to which dots have been added without decompressing the compressed data.

  In the above example, the color of the pixel corresponding to the dot is replaced with the color of the pixel immediately below the pixel corresponding to the pixel corresponding to the dot, but the adjacent pixel is limited to the bottom. Alternatively, other adjacent pixels may be used. Alternatively, a color value having the largest number of pixels among all adjacent pixels or an average value of color values of all pixels may be replaced.

  In the above example, as processing relating to the addition of dots to compressed original image data, addition of dots to compressed original image data and removal of dots from compressed original image data to which dots have been added are performed. 1 is performed by the PC 1 shown in FIG. However, it may be similarly performed by the MFP 2 shown in FIG. Further, at least a part of the functions of the PC 1 or the MFP 2 (for example, the pattern storage unit 309) is included in another device, and the PC 1 or the MFP 2 executes the above-described processing while communicating with the other device. May be. Furthermore, it is possible to provide a program for causing a computer to execute the above-described processing. Such a program is stored in a computer-readable recording medium such as a flexible disk attached to the computer, a CD-ROM (Compact Disk-Read Only Memory), a ROM (Read Only Memory), a RAM (Random Access Memory), and a memory card. And can be provided as a program product. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built in the computer. A program can also be provided by downloading via a network.

  The program according to the present invention is a program module that is provided as a part of a computer operating system (OS) and calls necessary modules in a predetermined arrangement at a predetermined timing to execute processing. Also good. In that case, the program itself does not include the module, and the process is executed in cooperation with the OS. A program that does not include such a module can also be included in the program according to the present invention.

  The program according to the present invention may be provided by being incorporated in a part of another program. Even in this case, the program itself does not include the module included in the other program, and the process is executed in cooperation with the other program. Such a program incorporated in another program can also be included in the program according to the present invention.

  The provided program product is installed in a program storage unit such as a hard disk and executed. The program product includes the program itself and a recording medium on which the program is recorded.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the specific example of the structural concept of PC concerning this Embodiment, and its peripheral device. 2 is a diagram illustrating a specific example of a configuration concept of an MFP functioning as an image processing apparatus. FIG. It is a block diagram which shows the hardware constitutions of PC concerning this Embodiment, and the specific example of the function. It is a block diagram which shows the specific example of the function structure of PC concerning this Embodiment. 10 is a flowchart showing a specific example of processing for embedding embedded data in a document image in the PC according to the present embodiment. 6 is a flowchart illustrating a specific example of processing for compressing document image data in the PC according to the embodiment. FIG. 4 is a diagram for explaining a method of compressing document image data in the PC according to the embodiment. It is a figure which shows the specific example of a data structure of the compressed data for 1 block. It is a figure which shows the specific example of a watermark image. It is a flowchart which shows the specific example of the embedded data conversion process in PC concerning 1st Embodiment. It is a flowchart which shows the specific example of a dot synthetic | combination process in PC concerning 1st Embodiment. It is a figure which shows the specific example of an additional pattern used with PC concerning 1st Embodiment. It is a figure which shows the specific example of arrangement | positioning of an additional pattern. It is a figure which shows the specific example of the compression data to which the dot was added. It is a flowchart which shows the specific example of the embedding data conversion process in PC concerning 2nd Embodiment. It is a figure which shows the specific example of an embedding pattern. It is a figure which shows the specific example of arrangement | positioning of an embedding pattern. It is a figure which shows the specific example of the dot pattern embedded in original image data. It is a figure which shows the specific example of an additional pattern used with PC concerning 2nd Embodiment. It is a figure which shows the specific example of arrangement | positioning of an additional pattern. It is a figure which shows the specific example of an additional pattern used with PC concerning 3rd Embodiment. It is a figure which shows the specific example of arrangement | positioning of an additional pattern. It is a figure explaining the dot synthetic | combination process in 3rd Embodiment.

Explanation of symbols

  1 PC, 2 MFP, 11 mouse, 12 keyboard, 13 monitor, 14 external storage device, 15 printer, 16 scanner, 21 operation panel unit, 22 scanner unit, 23 printer unit, 100 input / output I / F, 101 CPU, 102 Storage device 201 image processing unit 301 original image data input unit 302 compression unit 303 representative value calculation unit 304 image storage unit 305 embedded data input unit 306 conversion unit 307 synthesis processing unit 308 reading unit 309 Pattern storage unit.

Claims (10)

An image processing method for compressed image data,
The compressed image data includes information indicating a representative color associated with each pixel,
A specifying step for specifying a pixel corresponding to a dot position in the image data;
And a rewriting step of rewriting a correspondence relationship of a representative color with respect to a pixel corresponding to the position of the dot in the compressed image data. The compressed image data is configured to include the information in units of blocks,
The image processing method according to claim 1, wherein the specifying step and the rewriting step execute processing for each number of pixels of the compressed image data according to the number of pixels of the block.   The image processing method according to claim 2, wherein a unit of processing for the compressed image data in the specifying step and the rewriting step is a divisor pixel number excluding 1 of the pixel number of the block.   The image processing method according to claim 1, wherein the information indicating the representative color included in the compressed image data includes an area for storing information indicating a color corresponding to the dot. . The compressed image data includes, for each pixel, information specifying a representative color associated with the pixel, and information indicating the representative color,
The image processing method according to claim 1, wherein the rewriting step rewrites information specifying a representative color associated with the pixel for a pixel corresponding to the dot position. The compressed image data includes, for each pixel, information specifying a representative color associated with the pixel, and information indicating the representative color,
The image processing method according to claim 1, wherein the rewriting step rewrites information indicating a representative color. The image processing method is an image processing method for embedding embedded data in the compressed image data,
Inputting the embedded data;
Converting the embedded data into dots,
The rewriting step of rewriting the correspondence relationship of the representative color with respect to the pixel corresponding to the position of the dot in the compressed image data so as to be associated with the representative color corresponding to the dot. The image processing method according to any one of the above. The image processing method is an image processing method for removing the dots from the compressed image data to which dots are added,
In the rewriting step, the correspondence relationship of the representative color with respect to the pixel corresponding to the dot position in the compressed image data is determined according to the representative color associated with the pixel adjacent to the pixel corresponding to the dot position. The image processing method according to claim 1, wherein the image processing method is rewritten so as to be associated with the representative color. Obtaining means for obtaining compressed image data;
Image processing means for performing image processing on the compressed image data,
The compressed image data includes information indicating a representative color associated with each pixel,
The image processing means includes
A specifying step for specifying a pixel corresponding to a dot position in the image data;
An image processing apparatus that executes image processing including a rewriting step of rewriting a correspondence relationship of a representative color with respect to a pixel corresponding to the position of the dot in the compressed image data. A program for causing a computer to execute image processing on compressed image data,
The compressed image data includes information indicating a representative color associated with each pixel,
A specifying step for specifying a pixel corresponding to a dot position in the image data;
An image processing program for causing the computer to execute a rewriting step of rewriting a correspondence relationship of a representative color with respect to a pixel corresponding to a position of the dot in the compressed image data.

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