JP4683375B2 - Encoding device, decoding device, encoding method, decoding method, and programs thereof - Google Patents

Description

  The present invention creates an image dictionary that associates a plurality of image elements constituting an input multi-valued image with identification information of the image elements, and applies the created image dictionary to an encoding process, and The present invention relates to an encoding method.

For example, Non-Patent Document 1 discloses JBIG2 that efficiently encodes image elements. In JBIG2, in addition to encoding processing of a generic region (Generic Region), encoding processing of a text region (Text Region) is defined.
However, the method disclosed in Non-Patent Document 1 does not consider the encoding process and encoding method for a plurality of overlapping image elements.

ITU-T Recommendation T.88 (02/00), “Lossy / lossless coding of bi-level images”, [online], 1999, ITU-T, [searched on February 21, 2005], Internet < URL: http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-T.88>

  The present invention has been made from the above-described background, and an object thereof is to provide an encoding apparatus and an encoding method for encoding a plurality of overlapping image elements while suppressing deterioration in image quality.

In order to achieve the above object, a first encoding device according to the present invention includes a shape pattern composed of binary pixels, a binary density pattern in which halftone dots are regularly arranged corresponding to density values, and an image element consists of a receiving means for receiving a plurality of said image elements, the shape coding means for coding the shape pattern of a plurality of image elements received by said receiving means is accepted by said accepting means When a plurality of image elements overlap each other, for any one of the image elements, a shape reversing unit that inverts the value of a binary pixel constituting the shape pattern, and a binary of the plurality of image elements received by the receiving unit and density pattern, by using the binary density pattern identification information and each other the associated concentrations dictionary that identifies a plurality of images received by said receiving means And a concentration encoding means for encoding the binary density pattern of the unit.

A second encoding device according to the present invention is an image element composed of a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to the density values. Te, a receiving means for receiving a plurality of said image elements, the shape coding means for coding the shape pattern of a plurality of image elements received by the receiving unit, the two values of a plurality of image elements received by said receiving means Density coding for encoding binary density patterns of a plurality of image elements received by the accepting means using a density dictionary in which density patterns and identification information for identifying the binary density patterns are associated with each other If a unit, a plurality of image elements received by said receiving means overlap each other, for any image element, density inversion hand for inverting the binary density pattern With the door.

A first decoding device according to the present invention includes a receiving unit that receives code data including shape information and density information related to a plurality of image elements, and decodes shape information included in the code data received by the receiving unit. , For each of the plurality of image elements, a shape decoding means for obtaining a shape pattern composed of binary pixels or an inverted shape pattern obtained by inverting the values of the binary pixels constituting the shape pattern; and For each of the plurality of image elements , using a density dictionary in which binary density patterns in which halftone dots are regularly arranged corresponding to density values and identification information for identifying the binary density patterns are associated with each other , Decoding density information included in the code data received by the receiving means, and binary corresponding to the density values of each of the plurality of image elements A density decoding means for obtaining a degree pattern, and shape information decoded by the shape decoding means, wherein by using the decoded density information by the concentration decoding means, said plurality of image elements each image Data generating means for generating data.

Preferably, the data generation means uses the inverted shape pattern decoded by the shape decoding means and any of the plurality of binary density patterns acquired by the density decoding means. Generate image data of any of the image elements.
Preferably, the data generation means uses the shape pattern decoded by the shape decoding means and any one of a plurality of binary density patterns acquired by the density decoding means. The image data of the first image element among the plurality of image elements is generated, and the inverted shape pattern decoded by the shape decoding unit and the plurality of binary densities acquired by the density decoding unit Image data of a second image element among the plurality of image elements is generated using any other pattern.

Preferably, the data generation unit generates image data of an image element using any one of a plurality of binary density patterns acquired by the density decoding unit at least twice.
Preferably, the data generating means includes image data corresponding to the code data received by the receiving means, and a first binary density pattern among a plurality of binary density patterns acquired by the density decoding means. The shape pattern of the image element corresponding to the first binary density pattern among the image data after the exclusive OR operation and the pattern decoded by the shape decoding means And performing exclusive OR operation on the image data after the product operation and the second binary density pattern among the plurality of binary density patterns acquired by the density decoding means. Product operation of the image data after the logical OR operation and the inverted shape pattern of the image element corresponding to the second binary density pattern among the patterns decoded by the shape decoding means, And image data after product operation, XORing said second binary density pattern.

A second decoding device according to the present invention includes a receiving unit that receives code data including shape information and density information related to a plurality of image elements, and decodes shape information included in the code data received by the receiving unit. , For each of the plurality of image elements, shape decoding means for obtaining an image element shape pattern composed of binary pixels or an inverted shape pattern obtained by inverting the values of binary pixels constituting the shape pattern; A binary density pattern in which halftone dots are regularly arranged corresponding to the density values of image elements, an inverted binary density pattern obtained by inverting the binary density pattern, and identification information for identifying these patterns are associated with each other. was using the density dictionary, for each of the plurality of image elements, density information included in the code data received by said receiving means Density decoding means for decoding and obtaining binary density patterns or inverted binary density patterns corresponding to density values of each of the plurality of image elements, shape information decoded by the shape decoding means, and the density Data generation means for generating image data of each of the plurality of image elements using density information decoded by the decoding means.

A first program according to the present invention includes a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to density values in an encoding apparatus including a computer. an image element is an accepting step of accepting a plurality of the image elements, the shape encoding step for encoding the shape pattern of a plurality of image elements that are accepted, the plurality of image elements accepted overlap each other In this case, for any one of the image elements, a shape inversion step for inverting the values of the binary pixels constituting the shape pattern, the binary density patterns of the plurality of received image elements, and the binary density pattern are identified. using the density dictionary identification information is associated with each other to, to encode the binary density pattern of a plurality of image elements the accepted To perform the concentration encoding step to the computer of the encoding device.

A second program according to the present invention includes, in an encoding device including a computer, a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to density values. an image element is an accepting step of accepting a plurality of the image elements, the shape encoding step of encoding the shape pattern of a plurality of image elements in which the accepted, binary plurality of image elements the accepted A density encoding step for encoding binary density patterns of the plurality of received image elements using a density dictionary in which density patterns and identification information for identifying the binary density patterns are associated with each other; If multiple image elements the accepted overlap each other, for any image element, density inversion step of inverting the binary density pattern The causing a computer to execute the encoding device.

According to a third program of the present invention, in a decoding device including a computer, in the decoding device including the computer, a reception step of receiving code data including shape information and density information regarding a plurality of image elements; The shape information included in the encoded data is decoded, and for each of the plurality of image elements, a shape pattern constituted by binary pixels or an inverted shape pattern obtained by inverting the values of the binary pixels constituting the shape pattern is obtained. A density dictionary in which a shape decoding step to be acquired, a binary density pattern in which halftone dots are regularly arranged corresponding to density values of image elements, and identification information for identifying the binary density pattern are associated with each other. using, for each of the plurality of image elements, included in the code data received by said receiving means A density decoding step for decoding density information and obtaining a binary density pattern corresponding to each density value of the plurality of image elements, the decoded shape information, and the decoded density information are used. And causing the computer of the decoding device to execute a data generation step of generating image data of each of the plurality of image elements.

According to a fourth program of the present invention, in a decoding device including a computer, a reception step of receiving code data including shape information and density information regarding a plurality of image elements, and shape information included in the received code data Decoding for each of the plurality of image elements to obtain a shape pattern of an image element constituted by binary pixels or an inverted shape pattern obtained by inverting the values of binary pixels constituting the shape pattern A step, a binary density pattern in which halftone dots are regularly arranged corresponding to the density values of the image elements, an inverted binary density pattern obtained by inverting the binary density pattern, and identification information for identifying these patterns with the associated concentrations dictionary together, for each of the plurality of image elements, the accepted code data A density decoding step of decoding density information included and obtaining a binary density pattern or an inverted binary density pattern corresponding to density values of each of the plurality of image elements; the decoded shape information; and the decoding Using the converted density information, the computer of the decoding apparatus executes a data generation step of generating image data of each of the plurality of image elements.

  According to the encoding apparatus of the present invention, code data of an image including a plurality of overlapping image elements can be generated with high image quality and high compression rate.

First, in order to help understanding of the present invention, its background and outline will be described.
FIG. 1 is a diagram illustrating an encoding process and a decoding process based on JBIG2. FIG. 1 (A) illustrates the encoding process, and FIG. 1 (B) illustrates the decoding process.
As shown in FIG. 1A, the multi-value input image is separated into shape information and density information, and the shape information and density information are encoded respectively. When the input image is binarized, each image element (object) included in the input image becomes a binary image expressed in a pseudo gradation by the area gradation method.
The density information of such a binary image expressed in pseudo gradation is encoded by JBIG2 halftone area encoding. A halftone image element (in this example, a circle and a triangle) is composed of a plurality of halftone images (binary values) corresponding to density values (tone values), and is expressed in a pseudo gradation. The size of the halftone image corresponds to the density value (tone value). In the halftone area encoding process of JBIG2, these halftone images are registered in the image dictionary in association with density values, and a binary image composed of a halftone pattern is encoded. The code data includes a density value of each region in the input image and position information indicating a position where the density value exists.

  The shape information of each image element is encoded by JBIG2 text area encoding or generic area encoding. In the text area encoding process, a typical image pattern appearing in an input image is registered in an image dictionary in association with an index for identifying the image pattern, and the input image is encoded using the image dictionary. Generic region coding is a method of coding an input image without creating an image dictionary or the like. More specifically, generic region encoding encodes an input image using local pixel array statistics (for example, context).

  As shown in FIG. 1B, the decoding process is performed by a logical sum (OR) operation and a logical product (AND) operation. In the decoding process, the halftone image registered in the density dictionary is arranged by logical sum operation based on the code data of the density information, and the image shape indicating the shape of the image element is obtained based on the code data of the shape information. This is done by calculating the product of the image shape for the generated image. However, when decoding a plurality of image elements, an area where the image elements overlap may become a white area.

[First Embodiment]
A first embodiment of an image processing apparatus 2 according to the present invention will be described.
2A and 2B are diagrams for explaining the outline of the encoding process and the decoding process in the present embodiment. FIG. 2A shows the encoding process, and FIG. 2B shows the decoding process.
As shown in FIG. 2 (A), the image processing apparatus 2 in the present embodiment separates the image elements constituting the input image into its shape information and density information, and based on the shape information, The inverted image shape obtained by inverting the value of at least one image shape is encoded, and each halftone image is encoded based on the density information. Similar to the image shape, the inverted image shape is encoded by text region encoding or generic region encoding.

  As shown in FIG. 2B, the image element decoding process is performed by an exclusive OR (XOR) operation and an AND operation. The decoding process is performed by performing at least two exclusive OR operations when image elements are drawn in an overlapping manner. In this way, since a plurality of image elements are encoded by separating shape information and density information and decoded using exclusive OR operation, the image elements are highly compressed even when they overlap. It can be coded at a rate and decoded appropriately.

[Hardware configuration]
A hardware configuration of the image processing apparatus 2 in the present embodiment will be described.
FIG. 3 is a diagram illustrating the hardware configuration of the image processing apparatus 2 to which the encoding method and the decoding method according to the present invention are applied, centering on the control apparatus 20.
As illustrated in FIG. 3, the image processing apparatus 2 includes a control device 20 including a CPU 202 and a memory 204, a communication device 22, a storage device 24 such as an HDD / CD device, an LCD display device or a CRT display device, and a keyboard. A user interface device (UI device) 26 including a touch panel and the like is included.
The image processing device 2 is, for example, a general-purpose computer in which an encoding program 4 and a decoding program 5 described later are installed as part of a printer driver, and acquires image data via the communication device 22 or the storage device 24. The obtained image data is encoded or decoded and transmitted to the printer apparatus 10. Further, the image processing apparatus 2 may acquire image data optically read by the scanner function of the printer apparatus 10 and encode the acquired image data.

[Encoding program]
FIG. 4 is a diagram illustrating a functional configuration of the encoding program 4 that is executed by the control device 20 (FIG. 3) and implements the encoding method according to the present invention.
As illustrated in FIG. 4, the encoding program 4 includes a raster generation unit 400, an image dictionary creation unit 420, and a code generation unit 440. The image dictionary creation unit 420 includes a shape extraction unit 422, a halftone image extraction unit 424, an index assignment unit 426, and a shape inversion unit 428. The code generation unit 440 includes a shape information encoding unit 442 and a density information encoding unit. Part 444.
Note that all or some of the functions of the encoding program 4 may be realized by an ASIC provided in the printer apparatus 10 or the like.

In the encoding program 4, the raster generation unit 400 acquires image data (input image) in PDL (Page Description Language) format acquired via the communication device 22 or the storage device 24, and the acquired input image The image data is converted into raster data (color component image) of each color component, the raster data is subjected to screen processing, and output to the image dictionary creation unit 420 and the code generation unit 440. Further, the raster generation unit 400 specifies shape information, position information, and superimposition information of the image element included in the input image based on the image data in the PDL format, and the shape of the specified image element Information, position information, and superimposition information are output to the image dictionary creation unit 420.
Note that the encoding program 4 receives shape information, position information, and superimposition of image elements by pattern matching or the like when an input image rasterized in advance such as image data optically read by a scanner or the like is input. Information may be specified.

The image dictionary creation unit 420 is based on the input image, shape information, position information, and superimposition information of the image element input from the raster generation unit 400, and a density dictionary 710 (see FIG. 5) applied to the density information encoding process. And a shape dictionary 720 (described later with reference to FIG. 6) to be applied to the shape information encoding process, and the generated density dictionary 710 and shape dictionary 720 are output to the code generation unit 440. To do.
More specifically, the shape extraction unit 422 extracts the shape of the image element appearing in each color component image as a shape pattern based on the shape information and superimposition information of the image element input from the raster generation unit 400 and overlaps them. The shape reversing unit 428 inverts the shape of the image element that is an image element to be drawn on the upper side, and extracts a reversed shape pattern. The shape pattern of this example consists only of a shape (for example, edge information) and does not include density information and color information.
The shape reversing unit 428 generates a reversed shape pattern by inverting the value of the shape pattern of the image element under the control of the shape extracting unit 422, and outputs it to the shape extracting unit 422.

The halftone dot image extraction unit 424 extracts a halftone dot pattern that appears in each color component image based on the input image (binary image subjected to screen processing) input from the raster generation unit 400. The halftone dot pattern extracted by the halftone dot image extraction unit 424 is a halftone dot pattern corresponding to the density value of the image element, and does not include those existing in the edge region.
The index assigning unit 426 is an index for identifying each pattern with respect to the shape pattern (including the inverted shape pattern) extracted by the shape extracting unit 422 and the halftone dot pattern extracted by the halftone dot image extracting unit 424. Is granted. That is, the index assigning unit 426 generates a shape dictionary 720 (FIG. 6) by associating an index with a shape pattern, and generates a density dictionary 710 (FIG. 5) by associating an index (density value, etc.) with a halftone dot pattern. To do. The index is, for example, identification information generated individually for each input image, and may be a serial number assigned to the image pattern in the order in which the image pattern is extracted from the input image.

The code generation unit 440 encodes the image elements included in the input image based on the density dictionary 710 and the shape dictionary 720 input from the image dictionary creation unit 420, and the encoded image element code data and image dictionary ( The density dictionary 710 and the shape dictionary 720) are output to the storage device 24 (FIG. 3) or the printer device 10 (FIG. 3).
More specifically, the shape information encoding unit 442 compares the shape pattern registered in the shape dictionary 720 with the partial images included in each color component image, and matches or resembles any image pattern. The image data is replaced with the index corresponding to the shape pattern and the position information of the partial image. Furthermore, the shape information encoding unit 442 may encode the index and position information replaced with the partial image, the shape dictionary 720, and the like by entropy encoding (Huffman encoding, arithmetic encoding, LZ encoding, or the like). Further, based on the superimposition information of the image, the shape information encoding unit 442 encodes an image element obtained by inverting the value of the image element when the image elements overlap.

  The density information encoding unit 444 encodes the density information of the partial image included in each color component image based on the halftone dot pattern (density value) and the index registered in the density dictionary 710. For example, the density information encoding unit 444 outputs position information indicating the area of the partial image and the density value (that is, index) of the partial image in association with each other as code data of the density information of the partial image. .

5A and 5B are diagrams for explaining density information encoding processing. FIG. 5A illustrates an input image 600, and FIG. 5B illustrates a density dictionary 710 corresponding to the input image 600. FIG. 5C illustrates the code data of the density information of the input image 600.
As illustrated in FIG. 5A, the input image 600 may include a plurality of halftone density values. In this example, the halftone density value of the image element “triangle” and the halftone density value of the image element “circle” are different from each other. In such a case, the halftone image extraction unit 424 (FIG. 4) extracts a halftone pattern corresponding to each halftone density value. That is, when the halftone dot image extraction unit 424 has halftone dot patterns (except for the halftone dot pattern of the edge region) having different sizes in the input image 600, as illustrated in FIG. Each halftone dot pattern is extracted and registered in the density dictionary 710. In addition, since the shape of the halftone dot pattern may be different for each color component image, the halftone dot image extraction unit 424 uses a halftone dot pattern (edge region region) having different shapes in the input image 600 (a plurality of color component images). If a dot pattern is excluded, each dot pattern is extracted and registered in the density dictionary 710.

As illustrated in FIG. 5B, the index assigning unit 426 (FIG. 4), for each halftone dot pattern extracted by the halftone dot image extracting unit 424, identifies an index (identification). Information) is added to complete the density dictionary 710.
The density information encoding unit 444 (FIG. 4) encodes the density information of the input image based on the density dictionary 710 created as described above. Specifically, as illustrated in FIG. 5C, the density information encoding unit 444 specifies and specifies an area having a halftone dot pattern (that is, a density value) registered in the density dictionary 710. A pair of the position information of the area and the index corresponding to the halftone dot pattern of this area is used as code data of the density information.

6A and 6B are diagrams illustrating the encoding process of shape information. FIG. 6A illustrates an input image 600, and FIG. 6B illustrates a shape dictionary 720 corresponding to the input image 600. FIG. 6C illustrates the code data of the shape information of the input image 600.
As illustrated in FIG. 6A, the input image 600 may include a plurality of image elements having different shapes. In this example, the shape of the image element “triangle” is different from the shape of the image element “circle”.
The shape extraction unit 422 (FIG. 4) extracts a shape pattern indicating each image shape. That is, when there are a plurality of image elements having different contour shapes in the input image 600, the shape extraction unit 422 extracts the shape of each image element as a shape pattern as illustrated in FIG. 6B. Register in the shape dictionary 720. In addition, the shape extraction unit 422 causes the shape inversion unit 428 to invert the image shape of the second image element “circle” that overlaps the shape of the first image element “triangle” based on the superposition information, so that the inverted shape pattern Are extracted and registered in the shape dictionary 720. The shape inversion unit 428 inverts the shape pattern of the image element “circle” under the control of the shape extraction unit 422, and outputs it to the shape extraction unit 422.
Note that there may be a common image shape among a plurality of color component images constituting a color image (for example, when the image element “triangle” is a color image, the C color image element “triangle”). , M-color image element “triangle”, Y-color image element “triangle”, and K-color image element “triangle” may exist), and the shape extraction unit 422 is an image common to a plurality of color component images The shape is registered in the shape dictionary 720 as one shape pattern.

As illustrated in FIG. 6B, the index assigning unit 426 (FIG. 4) applies these shape patterns to each shape pattern (“triangle” and “circle”) extracted by the shape extraction unit 422. An identification index (identification information) is assigned to complete the shape dictionary 720.
The shape information encoding unit 442 (FIG. 4) encodes the shape information of the input image based on the shape dictionary 720 created as described above. Specifically, as illustrated in FIG. 6C, when the shape information encoding unit 442 finds in the input image 600 an image element whose shape substantially matches the shape pattern registered in the shape dictionary 720. In addition, a pair of position information indicating the region of the image element and an index of a shape pattern whose shape matches that of the image element is used as code data of the shape information.

FIG. 7 is a diagram illustrating code data 900 generated by the encoding program 4.
As illustrated in FIG. 7, the code data 900 includes a header including data attribute information, an image dictionary including a density dictionary 710 and a shape dictionary 720, and density information of the first image element (triangle). A halftone area code corresponding to code data, a text area code (or generic area code) corresponding to code data of shape information of the first image element (triangle), and a halftone of the second image element (circle) An area code, a text area code (or generic area code) corresponding to code data of the inverted shape information of the second image element (circle), and a second halftone area code of the second image element (circle) including.
In the density dictionary 710, halftone dot patterns included in the input image and indexes (density values and the like) for identifying these halftone dot patterns are registered in association with each other. In the shape dictionary 720, a shape pattern corresponding to the contour of an image element included in the input image and an index for identifying the shape pattern are registered in association with each other.

The halftone area codes of the first image element and the second image element have an index (that is, a density value) corresponding to the halftone dot pattern included in the input image and these halftone dot patterns (density values). A pair with position information indicating a region to be performed is included.
The text region code (or generic region code) of the first image element includes an index of a shape pattern corresponding to the shape of the image element included in the input image, and position information indicating a position where these image elements exist. A pair is included.
Further, the text area code (or generic area code) of the second image element includes an index of an inverted shape pattern obtained by inverting the shape value of the image element included in the input image, and a position where these image elements exist. A pair with the position information shown is included.

[Encoding operation]
FIG. 8 is a flowchart showing the encoding process (S10) by the encoding program 4.
As shown in FIG. 8, in step 100 (S100), when the PDL file is input as the input image 600, the raster generation unit 400, based on the input PDL file, the image elements included in the input image 600. Shape information, position information, and superimposition information are specified, and shape information, position information, and superimposition information of the specified image element are output to the image dictionary creation unit 420.
The shape extraction unit 422 of the image dictionary creation unit 420 includes image elements existing in the input image 600 (a plurality of color component images) based on the shape information, position information, and superimposition information of the image elements input from the raster generation unit 400. The shape pattern corresponding to the contour of the is determined. In addition, when the image elements are drawn with overlapping image elements, the shape extraction unit 422 causes the shape inversion unit 428 to extract a shape pattern obtained by inverting the shape of the image element.
Note that the shape extraction unit 422 of this example determines the shape pattern using the shape information specified based on the PDL file, but is not limited to this. For example, a rasterized multi-value image is obtained. The shape pattern may be determined by simple binarization with a predetermined threshold.

  The raster generation unit 400 converts the input image data of the input image 600 into raster data of each color component, performs screen processing on the raster data, and outputs the raster data to the image dictionary creation unit 420 and the code generation unit 440.

  In step 102 (S102), the halftone image extraction unit 424 extracts a halftone dot pattern from the raster data (binary image) of the input image input from the raster generation unit 400. More specifically, the halftone dot image extraction unit 424 removes the halftone dot pattern of the edge region from the raster data (screen-processed) of a plurality of color component images, and the remaining halftone dot pattern. A halftone dot pattern having a different shape or size is selected from the group.

In step 104 (S104), the index assigning unit 426 assigns an index for identifying each shape pattern to the shape pattern (including the inverted shape pattern) extracted by the shape extracting unit 422, thereby obtaining a shape dictionary. 720 is completed.
Further, the index assigning unit 426 completes the density dictionary 710 by assigning an index for identifying each halftone dot pattern to the halftone dot pattern extracted by the halftone dot image extracting unit 424.
The completed shape dictionary 720 is input to the shape information encoding unit 442, and the completed density dictionary 710 is input to the concentration information encoding unit 444.

  In step 106 (S106), the shape information encoding unit 442 compares the shape pattern registered in the shape dictionary 720 with the image element included in each color component image, and matches any shape pattern or shape. As the shape information of similar image elements, an index corresponding to the shape pattern and position information of the image elements are output.

  In step 108 (S108), the density information encoding unit 444 specifies the existence area of each density value corresponding to each halftone dot pattern registered in the density dictionary 710, and includes position information indicating the existence area of each density value. The index corresponding to each density value is output as density information.

  In step 110 (S110), the code generation unit 440 outputs the shape information (index and position information corresponding to the shape pattern or the inverted shape pattern) output from the shape information encoding unit 442 and the density information encoding unit 444. Density information (index and position information corresponding to the density value), a shape dictionary 720, a Huffman code corresponding to the density dictionary 710, and the like, and the generated code data (FIG. 7) as shape information, density information The code data of the shape dictionary 720 and the density dictionary 710 are output.

[Decryption program]
FIG. 9 is a diagram illustrating a functional configuration of the decryption program 5 that is executed by the control device 20 (FIG. 3) and implements the decryption method according to the present invention.
As illustrated in FIG. 9, the decoding program 5 includes a decoding processing unit 500, a density decoding unit 510, a shape decoding unit 520, and a decoded image generation unit 530.
Note that all or some of the functions of the decryption program 5 may be realized by an ASIC provided in the printer apparatus 10 or the like.

  In the decoding program 5, the decoding processing unit 500 decodes the input code data 900 (FIG. 7) into a set of indexes and position information, an image dictionary (a density dictionary 710 and a shape dictionary 720), and the like. The index and position information (that is, halftone area code) and the density dictionary 710 are output to the density decoding unit 510, the shape information index and position information (that is, text area code or generic area code), and the shape dictionary 720. Is output to the shape decoding unit 520.

  The density decoding unit 510 decodes the density information of the input image based on the density information index and position information input from the decoding processing unit 500 and the density dictionary 710. More specifically, the density decoding unit 510 arranges the halftone dot patterns registered in the density dictionary 710 in accordance with the index of the density information and the position information input from the decoding processing unit 500, so that FIG. A halftone dot image as illustrated is generated.

  The shape decoding unit 520 decodes the shape information of the image elements included in the input image based on the shape information index and position information input from the decoding processing unit 500 and the shape dictionary 720. More specifically, the shape decoding unit 520 arranges the shape patterns (including the inverted shape pattern) registered in the shape dictionary 720 according to the index and position information of the shape information input from the decoding processing unit 500. Then, an image shape as illustrated in FIG. 2 is created.

  Based on the density information decoded by the density decoding unit 510 and the shape information decoded by the shape decoding unit 520, the decoded image generation unit 530 decodes the code data of the input image 600 and generates a decoded image. To do. More specifically, the decoded image generation unit 530 first selects the first halftone image created by the density decoding unit 510 (a network arranged by, for example, an exclusive OR operation according to the index and position information). The first image is obtained by performing a join operation (for example, a product operation) between the point pattern) and the first image shape (the shape pattern arranged according to the index and position information) created by the shape decoding unit 520. An element (“triangle” shown in FIG. 2) is generated. Further, the decoded image generation unit 530 performs an exclusive OR operation on the second halftone image on the generated image, and then performs a second OR operation on the image after the exclusive OR operation. A product operation is performed on the image shape, and then the second halftone image is again subjected to an exclusive OR operation on the image after the product operation, thereby obtaining a second image element ("circle" )).

[Decryption operation]
FIG. 10 is a flowchart showing the decryption process (S20) by the decryption program 5.
As shown in FIG. 10, in step 200 (S200), the decoding processing unit 500 (FIG. 9) converts the input code data 900 (FIG. 7) into a halftone area code (index of density information and set of position information). ), Text region code or generic region code (shape information index and position information set), and image dictionary (density dictionary 710 and shape dictionary 720), and density information index and position information and density dictionary 710 are The data is output to the decoding unit 510, and the shape information index and position information and the shape dictionary 720 are output to the shape decoding unit 520.

In step 202 (S202), the density decoding unit 510 extracts the halftone pattern 1 from the density dictionary 710 based on the density information index and the position information input from the decoding processing unit 500, and extracts the extracted halftone pattern. Is placed in the area indicated by the position information. The image in which the halftone dot pattern is arranged is input to the decoded image generation unit 530 as the halftone image 1 (FIG. 2).
The decoded image generation unit 530 generates an image by performing an exclusive OR operation on the halftone image 1 created by the density decoding unit 510 and the generated image.

In step 204 (S204), the shape decoding unit 520 extracts the shape pattern corresponding to the index from the shape dictionary 720 based on the index and position information of the image shape 1 input from the decoding processing unit 500, and extracted. The shape pattern is arranged in the area indicated by the position information. The image in which the shape pattern is arranged is input to the decoded image generation unit 530 as the image shape 1 (FIG. 2).
In step 206 (S206), the decoded image generation unit 530 performs a product operation on the image shape 1 created by the shape decoding unit 520 and the generated image to generate an image.

In step 208 (S208), the density decoding unit 510 extracts the halftone pattern 2 from the density dictionary 710 based on the density information index and the position information input from the decoding processing unit 500, and extracts the extracted halftone pattern. Is placed in the area indicated by the position information. The image in which the halftone dot pattern is arranged is input to the decoded image generation unit 530 as the halftone image 2 (FIG. 2).
The decoded image generation unit 530 generates an image by performing an exclusive OR operation on the halftone image 2 created by the density decoding unit 510 and the generated image.

In step 210 (S210), the shape decoding unit 520 extracts a shape pattern corresponding to the index from the shape dictionary 720 based on the index and position information of the inverted image shape 2 input from the decoding processing unit 500, and is extracted. The shape pattern is arranged in the area indicated by the position information. The image in which the shape pattern is arranged is input to the decoded image generation unit 530 as the inverted image shape 2 (FIG. 2).
In step 212 (S212), the decoded image generation unit 530 performs a product operation on the inverted image shape 2 created by the shape decoding unit 520 and the generated image to generate an image.

In step 214 (S214), the density decoding unit 510 extracts the halftone dot pattern 2 again and arranges it in the region indicated by the position information. The image on which the halftone dot pattern is arranged is input again to the decoded image generation unit 530 as the halftone image 2.
The decoded image generation unit 530 performs an exclusive OR operation on the halftone image 2 and the generated image again to generate a decoded image (FIG. 2).

As described above, the image processing apparatus 2 according to the present embodiment is configured with a halftone dot pattern in a state in which edge information of image elements is held by separating and encoding shape information and density information. A binary image can be efficiently encoded.
Further, since the image processing apparatus 2 can independently reduce the redundancy of the shape information and the redundancy of the density information, a higher compression rate can be expected.
Further, the image processing apparatus 2 encodes the inverted image shape information obtained by inverting the shape value of the image element, uses the inverted image shape for the decoded image, and performs the exclusive OR operation on the halftone image at least twice. Since the calculation is performed, a plurality of image elements can be appropriately overlapped and drawn.

[Second Embodiment]
A second embodiment of the image processing apparatus 2 according to the present invention will be described.
FIG. 11 is a diagram for explaining the outline of the encoding process and the decoding process in the present embodiment, FIG. 11A shows the encoding process, and FIG. 11B shows the decoding process.
As shown in FIG. 11A, the image processing apparatus 2 according to the present embodiment encodes the image elements constituting the input image based on the shape information and encodes the halftone image based on the density information. The inverted halftone image obtained by inverting the value of at least one halftone image is encoded. The inverted halftone image is encoded by halftone region encoding in the same manner as the halftone image.
As shown in FIG. 11B, the decoding process of the image element is performed by an exclusive logical sum negation (XNOR) operation and a logical sum (OR) operation. The decoding process is performed by performing an exclusive OR negation operation at least twice when image elements are drawn in an overlapping manner. Thus, since a plurality of image elements are encoded with shape information and density information separated, the image elements can be encoded with a high compression rate. In addition, since at least one halftone image is inverted and encoded, and is decoded using an exclusive OR negation operation, even when image elements overlap, it can be appropriately decoded.

[Encoding program]
FIG. 12 is a diagram illustrating a functional configuration of the encoding program 6 which is executed by the control device 20 (FIG. 3) and implements the encoding method according to the present invention.
As illustrated in FIG. 12, the encoding program 6 includes a raster generation unit 400, an image dictionary creation unit 420, and a code generation unit 440. The image dictionary creation unit 420 includes a shape extraction unit 422, a halftone image extraction unit 424, an index assignment unit 426, and a halftone dot inversion unit 602. The code generation unit 440 includes a shape information encoding unit 442 and a density information code. Including a conversion unit 444 The encoding program 6 has a configuration in which the shape inversion unit 428 is deleted from the encoding program 4 (FIG. 4) and a halftone inversion unit 602 is added. 12 that are substantially the same as those shown in FIG. 4 are denoted by the same reference numerals.

In the encoding program 6, the shape extraction unit 422 extracts the shape of the image element appearing in each color component image as a shape pattern based on the shape information of the image element input from the raster generation unit 400.
The halftone dot image extraction unit 424 extracts a halftone dot pattern that appears in each color component image based on the input image (binary image subjected to screen processing) input from the raster generation unit 400. Also, the halftone image extraction unit 424 converts the halftone dot pattern of the image elements that are overlapping image elements to be drawn on the upper side based on the superimposition information of the image elements input from the raster generation unit 400 into halftone dots. The inverted halftone dot pattern is extracted by inverting the part 602.
The halftone dot inversion unit 602 generates a reverse halftone dot pattern by inverting the value of the halftone dot pattern under the control of the halftone dot image extraction unit 424, and outputs it to the halftone dot image extraction unit 424.

FIG. 13 is a diagram illustrating code data 910 generated by the encoding program 6.
As illustrated in FIG. 13, the code data 910 includes a header including data attribute information and the like, an image dictionary including a density dictionary 710 and a shape dictionary 720, and density information of the first image element (triangle). Halftone area code corresponding to code data, text area code (or generic area code) corresponding to code data of shape information of the first image element (triangle), and density information of the second image element (circle) A halftone area code corresponding to code data (including an inverted halftone dot pattern), a text area code (or generic area code) corresponding to code data of shape information of the second image element (circle), and And a second halftone region code of the second image element (circle). The code data 910 is different from the code data 900 shown in FIG. 7 in that it includes a halftone dot pattern inverted with respect to the second image element (circle) and non-inverted shape information.

[Encoding operation]
FIG. 14 is a flowchart showing the encoding process (S30) by the encoding program 6.
As illustrated in FIG. 14, in S <b> 100, the shape information of the image element is acquired by the raster generation unit 400 and the shape extraction unit 422 of the image dictionary creation unit 420.
In step 300 (S300), the halftone image extraction unit 424 extracts a halftone dot pattern from the raster data (binary image) of the input image input from the raster generation unit 400. In addition, when the image elements overlap, the halftone image extraction unit 424 controls the halftone dot inversion unit 602 to extract the inverted halftone dot pattern.
In the processing of S104 to S110, the encoding program 6 creates a density dictionary 710 and a shape dictionary 720, encodes shape information and density information, and outputs code data 910 shown in FIG.

[Decryption operation]
FIG. 15 is a flowchart showing the decryption process (S40) by the decryption program 7. Note that the decryption program 7 has substantially the same components as the decryption program 5 shown in FIG.
As shown in FIG. 15, in S <b> 200 to S <b> 206, the decoding program 7 decodes the input code data 910 and draws the first image element (triangle) by the halftone image 1 and the shape information 1.

In step 400 (S400), the density decoding unit 510 extracts the inverted halftone dot pattern 2 from the density dictionary 710 based on the density information index and position information input from the decoding processing unit 500, and extracts the extracted inverted network. The point pattern is arranged in the area indicated by the position information. The image on which the inverted halftone pattern is arranged is input to the decoded image generation unit 530 as the inverted halftone image 2 (FIG. 11).
The decoded image generation unit 530 generates an image by performing an exclusive OR operation on the inverted halftone image 2 generated by the density decoding unit 510 and the generated image.

In step 402 (S402), the shape decoding unit 520 extracts the shape pattern corresponding to the index from the shape dictionary 720 based on the index and position information of the image shape 2 input from the decoding processing unit 500, and extracted. The shape pattern is arranged in the area indicated by the position information. The image in which the shape pattern is arranged is input to the decoded image generation unit 530 as the image shape 2 (FIG. 11).
In step 212 (S212), the decoded image generation unit 530 adds up the image shape 2 created by the shape decoding unit 520 and the generated image to generate an image.

In step 404 (S404), the density decoding unit 510 extracts the inverted halftone pattern 2 again and arranges it in the area indicated by the position information. The image in which the inverted halftone dot pattern is arranged is input again to the decoded image generation unit 530 as the inverted halftone image 2.
The decoded image generation unit 530 performs an exclusive OR operation on the inverted halftone image 2 and the generated image again to generate a decoded image (FIG. 11).

  As described above, the image processing apparatus 2 in the present embodiment encodes an inverted halftone dot pattern obtained by inverting the value of the halftone dot pattern corresponding to the density information of the image element, and this inversion is performed on the decoded image. Since the exclusive OR of the halftone dot pattern is performed at least twice, a plurality of image elements can be appropriately overlapped and drawn.

[Third Embodiment]
A third embodiment of the image processing apparatus 2 according to the present invention will be described.
In this embodiment, the intermediate halftone area and refinement area of JBIG2 are used. First, in order to help understanding of the present invention, an outline of the intermediate halftone area and the refinement area will be described.
JBIG2 defines two types of buffers in which an image that is a decoding result of a region is placed. One of the buffers is a page buffer, which serves as an output of the decoder. The other is an auxiliary buffer, which is a buffer for placing intermediate data.
All regions, such as halftone regions, text regions, generic regions, can have an “intermediate” attribute. When the area has an intermediate attribute, the decoding result is placed not in the page buffer but in the auxiliary buffer. The area arranged in the auxiliary buffer can be drawn in the page buffer by using a refinement area described later. At this time, the area of the auxiliary buffer can be simply drawn in the page buffer, or can be drawn in the page buffer after changing the image.

FIGS. 16A and 16B are diagrams for explaining the relationship between the page buffer and the auxiliary buffer in decoding. FIG. 16A shows decoding of a text area, and FIG. 16B shows decoding of an intermediate text area.
As shown in FIG. 16A, when the text area has no intermediate attribute, the decoding result is arranged in the page buffer. As shown in FIG. 16B, when the text area has an intermediate attribute, the decoding result is arranged not in the page buffer but in the auxiliary buffer. Also in the halftone area and the generic area, if these areas have intermediate attributes, the decoding result is placed in the auxiliary buffer.

The refinement region is a region in which a known image is changed and an image different from this image is generated. As the known image of the refinement area, an area in the auxiliary buffer (that is, an area having an intermediate attribute) and an arbitrary area of the page buffer can be used.
FIG. 17 is a diagram for explaining the refinement area decoding. FIG. 17A shows the relationship between the auxiliary buffer area and the refinement area decoding, and FIG. 17B shows the page buffer and the refinement area. The relationship with the decryption of the comment area is shown.
As shown in FIG. 17A, when the refinement area is decoded with respect to the auxiliary buffer area, an image arranged in the auxiliary buffer is used and rendered in the page buffer. As shown in FIG. 17B, when the refinement area is decoded for the page buffer, the image in the page buffer is used and rendered in the page buffer. Also, the auxiliary buffer area can be used without changing the image and can be directly drawn in the page buffer.

[Encoding program]
FIG. 18 is a diagram illustrating code data 920 generated by the encoding program 8 of this embodiment. The encoding program 8 (not shown) has the same components as the encoding program 4 (FIG. 4).
As illustrated in FIG. 18, the code data 920 is data encoded by the encoding program 8 and represents the intermediate halftone area code (halftone area having an intermediate attribute) of the second image element (circle). Including. Code data 900 (FIG. 7) includes a plurality of halftone area codes of the same content, whereas code data 920 includes only one intermediate halftone area code for each density information.
In this way, the encoding program 8 can reduce the amount of code data.

[Encoding operation]
FIG. 19 is a flowchart showing the encoding process (S50) by the encoding program 8.
As shown in FIG. 19, in the processing of S100 to S106, the encoding program 6 creates a density dictionary 710 and a shape dictionary 720 from an input image, and encodes shape information.
In step 500 (S500), the encoding program 8 encodes the density information of the first image element (triangle) by halftone region encoding, and the density information of the second image element (circle) has an intermediate attribute. Encoding is performed by halftone area encoding.
Further, the encoding program 8 outputs the encoded data 920 shown in FIG. 18 in the process of S110.

[Decryption operation]
FIG. 20 is a flowchart showing the decryption process (S60) by the decryption program 9. The decryption program 9 (not shown) has the same components as the decryption program 5 (FIG. 9).
As shown in FIG. 20, in the process of S200, the decoding program 9 decodes the input code data (FIG. 18). When the intermediate halftone area is decoded, it is placed in the auxiliary buffer.
In step 600 (S600), the decoding program 9 decodes the halftone area of the page buffer to generate a halftone image 1.
In the processing of S202 to S206, the decoding program 9 draws the first image element (triangle) using the halftone image 1 and the image shape 1.

In step 602 (S602), the decoding program 9 generates an intermediate halftone area for the halftone image 2.
The decoding program 9 generates a refinement region using an auxiliary buffer, and generates a halftone image 2.
In the processing of S208 to S212, the decoding program 9 draws the second image element (circle) using the halftone image 2 and the image shape 2.
In step 604 (S604), the decoding program 9 generates the refinement region again using the auxiliary buffer, generates the halftone image 2, and performs the exclusive OR operation again to obtain the decoded image. Generate.
In this way, the decoding program 9 generates a halftone image 2 by generating an intermediate halftone region and a plurality of refinement regions. Since the halftone image 2 is encoded using the intermediate halftone area, it can be appropriately decoded even if it is not encoded a plurality of times.

  As described above, since the image processing apparatus 2 according to the present embodiment performs encoding using the intermediate halftone area, the code amount of the code data can be reduced. In addition, since the image processing apparatus 2 generates an intermediate halftone region and a plurality of refinement regions, the image processing apparatus 2 can perform at least two exclusive logical operations on image elements that are not encoded a plurality of times. The image elements can be appropriately overlapped and drawn.

It is a figure which illustrates the encoding process and decoding process based on JBIG2, FIG. 1 (A) shows an encoding process, FIG.1 (B) shows a decoding process. FIGS. 2A and 2B are diagrams for explaining the outline of an encoding process and a decoding process in the first embodiment, FIG. 2A shows the encoding process, and FIG. 2B shows the decoding process. It is a figure which illustrates the hardware constitutions of the image processing apparatus 2 with which the encoding method and decoding method concerning this invention are applied centering on the control apparatus 20. FIG. It is a figure which illustrates the function structure of the encoding program 4 which implement | achieves the encoding method concerning this invention. FIG. 5A illustrates an input image 600, FIG. 5B illustrates a density dictionary 710 corresponding to the input image 600, and FIG. (C) illustrates the code data of the density information of the input image 600. FIG. 6A illustrates an input image 600, FIG. 6B illustrates a shape dictionary 720 corresponding to the input image 600, and FIG. (C) illustrates the code data of the shape information of the input image 600. It is a figure which illustrates the code data 900 produced | generated by the encoding program 4. FIG. It is a flowchart which shows the encoding process (S10) by the encoding program 4. It is a figure which illustrates the function structure of the decoding program 5 which implement | achieves the decoding method concerning this invention. It is a flowchart which shows the decoding process (S20) by the decoding program 5. FIG. It is a figure explaining the outline of the encoding process and decoding process in 2nd Embodiment, FIG. 11 (A) shows an encoding process and FIG. 11 (B) shows a decoding process. It is a figure which illustrates the function structure of the encoding program 6 which implement | achieves the encoding method concerning this invention. It is a figure which illustrates the code data 910 produced | generated by the encoding program 6. FIG. It is a flowchart which shows the encoding process (S30) by the encoding program 6. FIG. It is a flowchart which shows the decoding process (S40) by the decoding program 7. FIG. It is a figure explaining the relationship between the page buffer and auxiliary buffer in decoding, FIG. 16 (A) shows decoding of a text area, FIG.16 (B) shows decoding of an intermediate text area. FIG. 17A is a diagram for explaining the decoding of the refinement area. FIG. 17A shows the relationship between the auxiliary buffer area and the refinement area decoding, and FIG. 17B shows the page buffer and the refinement area decoding. Shows the relationship. It is a figure which illustrates the code data 920 produced | generated by the encoding program 8. FIG. It is a flowchart which shows the encoding process (S50) by the encoding program 8. FIG. It is a flowchart which shows the decoding process (S60) by the decoding program 9. FIG.

Explanation of symbols

2 ... Image processing device 10 ... Printer device 20 ... Control device 202 ... CPU
204 ... Memory 22 ... Communication device 24 ... Storage device 4 ... Encoding program 400 ... Raster generation unit 420 ... Image dictionary creation unit 422 ... Shape extraction unit 424 ... Halftone dot image extraction unit 426 ... Index assignment unit 428 ... Shape inversion unit 440 ... Code generation unit 442 ... Shape information encoding unit 444 ... Density information encoding unit 710 ... Concentration dictionary 720 ... Shape dictionary 5 ... Decoding program 500 ... Decoding processing unit 510 ... Density decoding unit 520 ... Shape decoding unit 530 ... Decoded image generation unit 600 ... Input image 900 ..Code data

Claims (12)

An image element composed of a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to the density value, and receiving means for receiving a plurality of the image elements;
Shape encoding means for encoding shape patterns of a plurality of image elements received by the receiving means;
When a plurality of image elements received by the receiving unit overlap with each other, a shape inversion unit that inverts the value of a binary pixel constituting a shape pattern for any of the image elements ;
Using a density dictionary in which binary density patterns of a plurality of image elements received by the receiving unit and identification information for identifying the binary density patterns are associated with each other , An encoding device comprising: density encoding means for encoding a binary density pattern of an image element. An image element composed of a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to the density value, and receiving means for receiving a plurality of the image elements;
Shape encoding means for encoding shape patterns of a plurality of image elements received by the receiving means;
Using a density dictionary in which binary density patterns of a plurality of image elements received by the receiving unit and identification information for identifying the binary density patterns are associated with each other , Density encoding means for encoding binary density patterns of image elements;
An encoding apparatus comprising: a density inversion unit that inverts a binary density pattern for any one of the image elements when the plurality of image elements received by the reception unit overlap each other . Receiving means for receiving code data including shape information and density information regarding a plurality of image elements;
The shape information included in the code data received by the receiving means is decoded, and for each of the plurality of image elements, a shape pattern constituted by binary pixels or a value of the binary pixels constituting this shape pattern is obtained. Shape decoding means for acquiring an inverted inverted shape pattern;
Using the density dictionary in which the binary density pattern in which halftone dots are regularly arranged corresponding to the density value of the image element and the identification information for identifying the binary density pattern are associated with each other, the plurality of image elements For each, density decoding means for decoding density information included in the code data received by the receiving means, and obtaining a binary density pattern corresponding to the density value of each of the plurality of image elements;
Decoding comprising: data generation means for generating image data for each of the plurality of image elements using the shape information decoded by the shape decoding means and the density information decoded by the density decoding means Device. The data generation means uses any one of the plurality of image elements by using the inverted shape pattern decoded by the shape decoding means and any of the plurality of binary density patterns acquired by the density decoding means. The decoding device according to claim 3 , wherein the image data is generated. The data generation means uses the shape pattern decoded by the shape decoding means and any one of the plurality of binary density patterns acquired by the density decoding means, among the plurality of image elements. Using the inverted shape pattern decoded by the shape decoding unit and one of the plurality of binary density patterns acquired by the density decoding unit, generating image data of one image element, The decoding device according to claim 3 , wherein image data of a second image element among the plurality of image elements is generated. The decoding according to any one of claims 3 to 5 , wherein the data generation unit generates image data of an image element by using any one of a plurality of binary density patterns acquired by the density decoding unit at least twice. Device. The data generating means exclusively outputs image data corresponding to the code data received by the receiving means and a first binary density pattern among a plurality of binary density patterns acquired by the density decoding means. Logical OR operation, product operation of the image data after the exclusive OR operation and the shape pattern of the image element corresponding to the first binary density pattern among the patterns decoded by the shape decoding means Then, an exclusive OR operation is performed on the image data after the product operation and the second binary density pattern among the plurality of binary density patterns acquired by the density decoding means, and this exclusive OR operation is performed. A product operation is performed on the subsequent image data and the inverted shape pattern of the image element corresponding to the second binary density pattern among the patterns decoded by the shape decoding means, and the product operation And image data decoding apparatus according to claim 6, exclusive OR operation and said second binary density pattern. Receiving means for receiving code data including shape information and density information regarding a plurality of image elements;
The shape information included in the code data received by the receiving means is decoded, and for each of the plurality of image elements, the shape pattern of an image element composed of binary pixels or the binary pixels constituting this shape pattern Shape decoding means for acquiring an inverted shape pattern obtained by inverting the value of
A binary density pattern in which halftone dots are regularly arranged corresponding to the density values of image elements, an inverted binary density pattern obtained by inverting the binary density pattern, and identification information for identifying these patterns are associated with each other. For each of the plurality of image elements, the density information included in the code data received by the receiving unit is decoded using the density dictionary, and a binary density pattern corresponding to the density value of each of the plurality of image elements Or density decoding means for obtaining an inverted binary density pattern;
Decoding comprising: data generation means for generating image data for each of the plurality of image elements using the shape information decoded by the shape decoding means and the density information decoded by the density decoding means Device. In an encoding device including a computer, an image element including a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to density values, A reception step for receiving a plurality of elements ;
A shape encoding step of encoding a shape pattern of the accepted plurality of image elements;
A shape inversion step of inverting the value of a binary pixel constituting a shape pattern for any one of the image elements when the received plurality of image elements overlap each other ;
Using the density dictionary in which the binary density pattern of the received plurality of image elements and the identification information for identifying the binary density pattern are associated with each other, the binary density of the received plurality of image elements A program for causing a computer of the encoding apparatus to execute a density encoding step for encoding a pattern. In an encoding device including a computer, an image element including a shape pattern composed of binary pixels and a binary density pattern in which halftone dots are regularly arranged corresponding to density values, A reception step for receiving a plurality of elements ;
A shape encoding step of encoding a shape pattern of the accepted plurality of image elements ;
Using the density dictionary in which the binary density pattern of the received plurality of image elements and the identification information for identifying the binary density pattern are associated with each other, the binary density of the received plurality of image elements A density encoding step for encoding the pattern;
A program that causes the computer of the encoding apparatus to execute a density inversion step of inverting a binary density pattern for any one of the image elements when the received plurality of image elements overlap each other . In a decoding apparatus including a computer, an accepting step of receiving code data including shape information and density information regarding a plurality of image elements;
The shape information included in the received code data is decoded, and for each of the plurality of image elements, a shape pattern composed of binary pixels or an inversion obtained by inverting the values of the binary pixels constituting the shape pattern A shape decoding step for obtaining a shape pattern;
Using the density dictionary in which the binary density pattern in which halftone dots are regularly arranged corresponding to the density value of the image element and the identification information for identifying the binary density pattern are associated with each other, the plurality of image elements For each, a density decoding step for decoding density information included in the code data received by the receiving means and obtaining a binary density pattern corresponding to the density value of each of the plurality of image elements;
A program that causes a computer of the decoding device to execute a data generation step of generating image data of each of the plurality of image elements using the decoded shape information and the decoded density information. In a decoding apparatus including a computer, an accepting step of receiving code data including shape information and density information regarding a plurality of image elements;
The shape information included in the received code data is decoded, and for each of the plurality of image elements, a shape pattern of an image element composed of binary pixels or a value of a binary pixel constituting the shape pattern is obtained. A shape decoding step to obtain an inverted inverted shape pattern;
A binary density pattern in which halftone dots are regularly arranged corresponding to the density values of image elements, an inverted binary density pattern obtained by inverting the binary density pattern, and identification information for identifying these patterns are associated with each other. For each of the plurality of image elements, the density information included in the received code data is decoded using the density dictionary, and a binary density pattern or an inverted binary pattern corresponding to the density value of each of the plurality of image elements is decoded. A density decoding step for obtaining a value density pattern;
A program that causes a computer of the decoding apparatus to execute a data generation step of generating image data of each of the plurality of image elements using the decoded shape information and the decoded density information.

Images