JP4860558B2 - Encoding apparatus and encoding method - Google Patents

Description

  The present invention relates to an encoding apparatus and an encoding method for generating a structured document by encoding an image.

  2. Description of the Related Art Conventionally, there is a technique for encoding an image such as a document in which characters and pictures are mixed (picture mixed document). In order to encode such a picture mixed document at a high compression rate, there is a technique for forming an encoded image as a structured document (see, for example, Patent Documents 1 and 2). A structured document is an image component analysis of a mixed pattern document and separated into a pattern portion and an edge portion. For example, an image representing a pattern portion is used as a background, an image representing an edge portion is used as a mask, and an edge color is represented. An image is used as a foreground, and these are independently encoded to generate code data, and then each of these code data is assembled into one file format. If a structured document is generated by encoding a mixed picture document using such an encoding method, compared to an encoding method that encodes a mixed picture document as one multi-valued image when encoded at a high compression rate. Can provide higher image quality.

Japanese Patent No. 3275807 USP Re35,657, USP 5,778,092 “Method and apparatus for compressing color array scale documents”, Xerox Corporation

  However, in the conventional technique as shown in Patent Document 1, it takes a considerable amount of processing time to separate the edge portion and the pattern portion.

  The present invention has been made in view of the above, and an object of the present invention is to provide an encoding apparatus and an encoding method capable of reducing the processing time required to generate a high-quality structured document.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is an encoding device that encodes an input image and generates a structured document including a foreground, a background, and a mask. Assigning a first multi-valued image as the foreground, assigning a second multi-valued image as the background, assigning a binary image as the mask, and encoding the foreground, the background and the mask, respectively, An assembling unit that generates the structured document by assembling the foreground, the background, and the mask encoded by the encoding unit according to a predetermined file format, and the encoding unit is arbitrarily configured as the first multi-valued image. First encoding means for encoding the image of the input image by a multi-level encoding system, second encoding means for encoding the input image as the second multi-level image by a multi-level encoding system, And having a third coding means for coding the binary image encoding scheme an image representing white as a binary image.

  The invention according to claim 2 is the invention according to claim 1, wherein the first encoding means encodes an image representing white as the first multi-value image by a multi-value encoding method. .

  The invention according to claim 3 is an encoding device that encodes an input image to generate a structured document including a foreground, a background, and a mask, and assigns a first multi-valued image as the foreground, and the background Assigning a second multi-valued image as the mask, assigning a binary image as the mask, encoding the foreground, the background and the mask, respectively, and the foreground, the background and the encoding encoded by the encoding means Assembly means for generating a structured document by assembling the mask according to a predetermined file format, wherein the encoding means encodes the input image as the first multi-value image by a multi-value encoding method. Encoding means; second encoding means for encoding an arbitrary image as the second multi-value image by a multi-value encoding method; and binary image encoding for an image representing black as the binary image And having a third coding means for coding the equation.

  The invention according to claim 4 is an encoding device that encodes an input image to generate a structured document composed of a foreground, a background, and a mask, wherein the input image is a multi-valued image encoding method as the background. Encoding means for encoding according to the above, the background encoded by the encoding means, an encoded foreground in which an arbitrary image is encoded in advance by a multi-level encoding method and stored in the first storage means, Assembly means for generating a structured document by assembling an encoded mask stored in the second storage means in advance in accordance with a binary encoding method and an encoded mask stored in the second storage means. Features.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the first encoding means is configured such that all the values of the pixels constituting the first multi-valued image are 0, or the first The first multi-valued image is encoded by a multi-level encoding method so that all the values of the pixels constituting the expanded image when the one multi-valued image is expanded are 0.

  According to a sixth aspect of the present invention, in the first aspect of the invention, the third encoding means is configured such that all the values of the pixels constituting the binary image are 0 or the binary image is expanded. The binary image is encoded by a binary encoding method so that all the values of the pixels constituting the expanded image are 0.

  The invention according to claim 7 is the invention according to claim 3, wherein the third encoding means is configured such that all the values of the pixels constituting the binary image are 1 or the binary image is expanded. The binary image is encoded by a binary encoding method so that all the values of the pixels constituting the expanded image are 1.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the image is a JPEG2000 family file defined by IS15444 series, an international standard IS154444-1 JPEG2000 IMAGE CODING SYSTEM: Core. JPEG2000 code stream shown in Coding System, International Standard IS154444-1 JPEG2000 IMAGE CODING SYSTEM: JPEG2000 file shown in Core Coding System, International Standard IS15444-2 JPEG2000 IMAGE CODING2000 Standard JPEG4 Indication It is characterized by being an image represented by at least one of the JPEG 2000 file indicated by the Motion JPEG2000 file indicated by the JPEG2000 part 3 file and the international standard IS15444-6 INFORMATIONTECHNOLOGY-JPEG2000 IMAGE Coding System: Part6: Compound Image File. .

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the structured document is an international standard IS15444-6 INFORMATIONTECHNOLOGY-JPEG2000 IMAGE Coding System: Part 6: Compound Image File Format. It is an image represented by at least one file format among a JPEG 2000 part 6 file shown, a PDF file indicated by PDF: Portable Document Format, a PostScript file, and a Djvu file.

  The invention according to claim 10 is an encoding method for generating a structured document composed of a foreground, a background, and a mask by encoding an input image, wherein a first multi-valued image is assigned as the foreground, and the background Assigning a second multi-valued image as a mask, assigning a binary image as the mask, and encoding each of the foreground, the background and the mask, and the foreground, the background and the encoding encoded by the encoding means An assembly step of generating a structured document by assembling the mask according to a predetermined file format, wherein the encoding step encodes an arbitrary image as the first multi-value image by a multi-value encoding method. An encoding step, a second encoding step for encoding the input image as the second multi-level image by a multi-level encoding method, and white as the binary image. The to images; and a third encoding step of encoding the binary image encoding scheme.

  According to the present invention, it is possible to reduce the processing time required to generate a high-quality structured document.

  Exemplary embodiments of an encoding apparatus and an encoding method according to the present invention will be explained below in detail with reference to the accompanying drawings.

(1) Configuration A configuration of the encoding device 1 according to the present embodiment will be described. The encoding device 1 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an external storage device such as an HDD (Hard Disk Drive) and a CD (Compact Disk) drive device. A communication I / F, an operation device to which an operation from a user is input, a display device for displaying information, and a bus for connecting them (none shown), and using a normal computer It has a hardware configuration. Various programs and various data are stored in the external storage device. Also, the external storage device stores, for example, code data (JPM file) obtained by encoding a document image read by a scanner in a structured document file format (for example, JPM). A structured document is a general office document (referred to as a mixed picture document) in which constituent elements such as character parts consisting of characters and picture parts consisting of pictures are mixed. It is composed of a plurality of layout objects having a mask for switching between the foreground and the background. Here, since the foreground and the background are high-definition color images, they are encoded by the JPEG2000 encoding method so as to perform tile division or precinct division, and each is divided into four. On the other hand, the mask is encoded by a binary image encoding method having no division structure such as MH / MR / MMR. Hereinafter, such a mask is referred to as a binary mask. Various programs and various data are stored in the ROM. The CPU loads the various programs stored in the ROM and the external storage device to the RAM and executes them, thereby controlling the entire device and realizing various functions. In particular, in the present embodiment, the CPU realizes a function of generating a structured document by encoding a design mixed document.

  Here, the function in which the encoding apparatus 1 encodes a design mixed document to generate a structured document will be briefly described. FIG. 1 is a diagram conceptually showing a function of the encoding apparatus 1 for generating a structured document by encoding a mixed picture document. The encoding device 1 assigns images to the foreground G2, the background G3, and the mask G4, which are the objects of the structured document, using the design mixed document G1. The background and foreground are binary images or multivalued images, and the mask is a binary image. Then, the encoding device 1 encodes the image assigned to the foreground G2 using the multilevel encoding method, encodes the image assigned to the background G3 using the multilevel encoding method, and converts the image assigned to the mask G4 to the binary image. Encoding is performed by an encoding method. Then, the encoding device 1 generates a structured document G5 by assembling the encoded images. Here, what is characteristic in the present embodiment is that the foreground G2, the background G3, and the mask G4 are obtained not by separation from the mixed picture document but by image assignment. How to assign an image will be described in the operation column described later.

  Next, functions realized in the encoding device 1 when the CPU of the encoding device 1 executes various programs will be described. FIG. 2 is a block diagram showing a functional configuration of the encoding device 1. The functional configuration of the encoding device 1 includes an input file parser means 11, an encoding means 12, and an assembly means 13.

  The input file parser means 11 reads a picture mixed document (input file 10) inputted as a processing target from an external storage device, and interprets the state of the picture mixed document by reading information written in the picture mixed document. Such information is written, for example, in the header of the mixed picture document. Specifically, the input file parser means 11 interprets whether the picture mixed document is already compressed or uncompressed as the state of the mixed picture document, or interprets whether the mixed picture document consists of a plurality of pages. Or When the input mixed picture document is uncompressed and consists of a plurality of pages, the input file parser means 11 divides the mixed picture document into pages and passes them to the encoding means 12.

  The encoding means 12 assigns an image to each object (foreground, background and mask) of the structured document for each page of the mixed picture document delivered from the input file parser means 11, and assigns each object to a predetermined code. Each encoding is performed according to the encoding method. The specific operation of the encoding means 12 will be described in detail in the operation column described later.

  The assembling means 13 assembles each code data (code stream) encoded by the encoding means 12 according to a predetermined data format. Schematically, the assembling means 13 superimposes images in the order of background and mask in the above-described code data, and replaces pixels representing black in the mask with corresponding pixels in the foreground. The assembling means 13 outputs the structured document thus assembled as an output file 14 to the external storage device.

(2) Operation Next, the operation of the encoding device 1 will be described. FIG. 3 is a flowchart showing a procedure of processing in which the encoding apparatus 1 generates a structured document by encoding a design mixed document. When the user inputs an encoding request for a mixed picture document to be processed through the operation device, the encoding device 1 accepts the input of the encoding request (step S1). The encoding request input here includes, for example, a file name (input file name) of a mixed picture document to be processed, a file name (output file name) of a structured document after processing, and a compression rate ( For example, 1/500) is included. Then, the input file parser means 11 of the encoding device 1 reads a picture mixed document having the input file name included in the encoding request from the external storage device (step S2). The input file parser means 11 determines whether or not the read mixed picture document is uncompressed (step S3). If the determination result is affirmative, the input file parser means 11 reads the read mixed picture document on the page. Each time it is decomposed, it is delivered to the encoding means 12.

  The encoding unit 12 performs the following processing for each page on the mixed picture document to which the input file parser unit 11 has been delivered. The encoding means 12 assigns an image to each object (background, foreground, mask) of the structured document (step S4). Specifically, the encoding unit 12 assigns the entire image of one page as a background, assigns an entire white image as a mask, and assigns an entire white image as a foreground. That is, here, the encoding apparatus 1 does not separate the picture mixed document into image parts and edge parts by analyzing the image components, and assigns the image of the mixed picture document to the background. Then, conventionally, for example, the encoding device 1 assigns a full white image as a dummy image to a mask representing an image of an edge portion. That is, the encoding apparatus 1 assigns an image representing a state where there is no edge portion to the mask. The foreground to which the image representing the color of the edge portion is assigned is in a state in which there is no color to be represented because there is no edge portion in the mask. For this reason, the image assigned to the foreground may be any image, but here, the encoding device 1 assigns an entirely white image for convenience. Further, the color may be other than white, and the color pattern may not be the entire surface but may be another pattern. In general, it is preferable that all patterns have the same value so as to increase the compression rate.

  Then, the encoding means 12 encodes the foreground to which the image is assigned as described above by the multi-value image encoding method (step S5), encodes the background by the multi-value image encoding method (step S6), and sets the mask. Encoding is performed by a binary image encoding method (step S7). Note that the encoding unit 12 also appropriately performs a process of quantizing with a predetermined threshold when the mask is encoded by the binary image encoding method.

  The assembling means 13 generates a structured document by repeating a series of operations for assembling code data obtained by encoding the respective objects according to a predetermined file format and assembling a code stream for each page (step S8). ). The procedure of the process in which the assembling means 13 generates the structured document by assembling the background, foreground, and mask according to a predetermined file format is the same as that according to the well-known MRC (Mixed Raster Content) encoding method. Then, the explanation is omitted. Then, the assembling means 13 outputs the generated structured document to the external storage device with the output file name included in the encoding request received in step S1, while outputting the processing result to the display device (step S9). ).

  As described above, when a structured document is generated by encoding a mixed picture document at a high compression rate, images are assigned to the background, foreground, and mask. For this reason, it is not necessary to perform image component analysis on a mixed picture document and separate it into a background, foreground, and mask. Therefore, a high-quality image can be provided without taking much processing time.

[Modification]
Moreover, it is not limited to each embodiment mentioned above, The various deformation | transformation which is illustrated below is possible.

<Modification 1>
The various programs executed by the encoding apparatus 1 of the above-described embodiment are files in an installable or executable format, such as a CD-ROM, a flexible disk (FD), a CD-R, and a DVD (Digital Versatile Disk). For example, the program may be recorded on a computer-readable recording medium. Further, the program may be provided by being stored on a computer connected to a network such as the Internet and downloaded to the encoding device 1 via the network.

<Modification 2>
In the above-described embodiment, the encoding unit 12 assigns the entire white image as the mask and the entire white image as the foreground. However, the encoding unit 12 assigns the value of a pixel constituting the encoded image obtained by encoding the image or What is necessary is just to encode so that the values of the pixels constituting the expanded image when the encoded image is expanded are all “0”.

<Modification 3>
In the embodiment described above, the encoding unit 12 is configured to assign the entire image of one page to the background of the structured document for the design mixed document, but it may be assigned to the foreground. FIG. 4 is a diagram conceptually showing a function of the encoding apparatus 1 according to the present modification for generating a structured document by encoding a design mixed document. In this case, a black image is assigned to the mask G4. Although an arbitrary image can be assigned to the background G3, here, as an example, an entire white image is assigned. According to such a configuration, when the assembling means 13 superimposes the mask image on the background image in step S5 of FIG. 3, all the pixels of the mask are replaced with the corresponding pixels of the foreground. As a result, the image that appears is the foreground image, which is the same as the entire one-page image of the mixed picture document. Therefore, even when the structured document is generated from the mixed picture document, it is not necessary to separate the mixed picture document into the background, the foreground, and the mask by using the image component analysis. It is possible to provide a high-quality image without the need.

  Although a black image is assigned as a mask as a mask, the encoding means 12 uses the values of the pixels constituting the encoded image obtained by encoding the image or the pixels constituting the expanded image when the encoded image is expanded. Encoding may be performed so that the values of all become “1”.

<Modification 4>
In the above-described embodiment, the encoding unit 12 may encode each object (foreground, background, mask) of the structured document at the time of assembling them or before they are assembled. good. The case of encoding before assembling these is, for example, a case where code data (code stream) obtained by previously encoding an image is prepared in advance. FIG. 5 conceptually shows a function in which the encoding apparatus 1 generates a structured document using a code stream in which a foreground image and a mask image are encoded in advance when an image mixed document is encoded. It is a figure. An encoded foreground code stream M1 shown in the figure is a code stream obtained by previously encoding the foreground by a multi-level encoding method, and is stored in, for example, an external storage device. Note that the foreground image before encoding is, as an example, a full white image or an arbitrary image, as in the above-described embodiment. The encoded mask code stream M2 is a code stream obtained by previously encoding a mask using a binary image encoding method, and is stored in, for example, an external storage device. Note that the mask before encoding is a white image as in the above-described embodiment. The assembling means 13 assembles a structured document by using the background code stream encoded by the encoding means 12 and the encoded foreground code stream and encoded mask code stream stored in advance in the external storage device. Generate.

  Even with such a configuration, a high-quality image can be provided without taking much processing time.

  Similarly, in the above-described third modification, a code stream in which a mask and a background are encoded is stored in advance in an external storage device or the like, and the assembling means 13 assembles these and the above-mentioned foreground. Also good.

<Modification 5>
In the above-described embodiment, a mixed picture document is handled as an image to be encoded by the encoding device 1. However, the present invention is not limited to this, and a multi-value image including only a pattern or a photo or a binary image including only a character is encoded. It may be a target of conversion.

  In addition, an image to be encoded by the encoding apparatus 1 is a JPEG2000 family file defined by IS15444 series, an international standard IS15444-1 JPEG2000 IMAGE CODING SYSTEM: a JPEG2000 code stream indicated by a Core Coding System, an international standard IS154444-1 JPEG2000. IMAGE CODING SYSTEM: JPEG2000 file shown in Core Coding System, international standard IS15444-2 JPEG2000 IMAGE CODING SYSTEM: JPEG2000 file shown in EXTENSIONS, JPEG2000 part file shown in international standard IS15444-3 MOTION JPEG2000 JPEG2000 file and international standard IS15444-6 INFORMATIONTECHNOLOGY-JPEG2000 IMAGE Coding System: Part6: may be an image represented by at least one file format among the JPM file indicated by the Compound Image File.

  In addition, the structured document generated by the encoding device is an international standard IS15444-6 INFORMATIONTECHNOLOGY-JPEG2000 IMAGE Coding System: Part6: JPEG2000 Part6 file indicated by Compound Image File Format, PDF: Portable Document file, PDF file format format file. And an image represented in at least one file format among the Djvu files.

  The present invention is suitable for use in an encoding technique for generating a structured document by encoding an image.

It is the figure which showed notionally the function in which the encoding apparatus 1 concerning one embodiment of this invention encodes a design mixed document, and produces | generates a structured document. It is a block diagram which shows the functional structure of the encoding apparatus 1 concerning the embodiment. It is a flowchart which shows the procedure of the process which the encoding apparatus 1 concerning the embodiment encodes a design mixed document and produces | generates a structured document. It is the figure which showed notionally the function in which the encoding apparatus 1 concerning the modification of the embodiment encodes a pattern mixed document, and produces | generates a structured document. The encoding apparatus 1 according to the modification of the embodiment generates a structured document using a code stream in which a foreground image and a mask image are encoded in advance when encoding a mixed picture document. It is the figure which showed the function notionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Encoding apparatus 11 Input file parser means 12 Encoding means 13 Assembly means

Claims (10)

An encoding device that encodes an input image to generate a structured document composed of a foreground, a background, and a mask,
Encoding means for assigning a first multivalued image as the foreground, assigning a second multivalued image as the background, assigning a binary image as the mask, and encoding the foreground, the background and the mask, respectively;
Assembly means for assembling the foreground, the background, and the mask encoded by the encoding means according to a predetermined file format to generate a structured document;
The encoding means includes
First encoding means for encoding an arbitrary image as the first multi-level image by a multi-level encoding method;
Second encoding means for encoding the input image as the second multi-level image by a multi-level encoding method;
An encoding apparatus comprising: third encoding means for encoding an image representing white as the binary image by a binary image encoding method. The encoding apparatus according to claim 1, wherein the first encoding unit encodes an image representing white as the first multi-level image by a multi-level encoding method. An encoding device that encodes an input image to generate a structured document composed of a foreground, a background, and a mask,
Encoding means for assigning a first multivalued image as the foreground, assigning a second multivalued image as the background, assigning a binary image as the mask, and encoding the foreground, the background and the mask, respectively;
Assembly means for generating a structured document by assembling the foreground, the background, and the mask encoded by the encoding means in a predetermined file format;
The encoding means includes
First encoding means for encoding the input image as the first multi-level image by a multi-level encoding method;
A second encoding means for encoding an arbitrary image as the second multi-level image by a multi-level encoding method;
An encoding apparatus comprising: third encoding means for encoding an image representing black as the binary image by a binary image encoding method. An encoding device that encodes an input image to generate a structured document composed of a foreground, a background, and a mask,
Encoding means for encoding the input image as the background by a multilevel image encoding method;
The background encoded by the encoding means, the encoded foreground in which an arbitrary image is encoded in advance by the multi-level encoding method and stored in the first storage means, and the image representing white are binary encoded An encoding apparatus comprising: an assembling unit that assembles an encoded mask that has been encoded in advance by a method and stored in a second storage unit in a predetermined file format to generate a structured document. The first encoding unit is configured such that all the values of the pixels constituting the first multi-valued image are 0, or all the values of the pixels constituting the expanded image when the first multi-valued image is expanded are 0. The encoding apparatus according to claim 1 or 2 , wherein the first multi-valued image is encoded by a multi-level encoding method so that The third encoding means is configured such that all the values of the pixels constituting the binary image are 0, or all the values of the pixels constituting the expanded image when the binary image is expanded are 0. The encoding apparatus according to claim 1, wherein the binary image is encoded by a binary encoding method. The third encoding means is such that all the values of the pixels constituting the binary image are 1, or all the values of the pixels constituting the expanded image when the binary image is expanded are 1. The encoding apparatus according to claim 3, wherein the binary image is encoded by a binary encoding method. The image includes a JPEG2000 family file defined by IS15444 series, an international standard IS154444-1 JPEG2000 IMAGE CODING SYSTEM: a JPEG2000 code stream represented by a Core Coding System, and an international standard IS15444-1 JPEG2000 IMAGE CODING SYSTEM: a Core Coding 2000 file. , International Standard IS15444-2 JPEG2000 IMAGE CODING SYSTEM: JPEG2000 file indicated by EXTENSIONS, International Standard IS15444-3 MOTION JPEG2000 file indicated by JPEG2000 Part 3 file indicated by JPEG2000 and International Standard IS1 444-6 INFORMATIONTECHNOLOGY-JPEG2000 IMAGE Coding System: Part6: Image represented in at least one file format among JPM files indicated by Compound Image File. The encoding device described in 1. The structured document is an international standard IS15444-6 INFORMATIONTECHNOLOGY-JPEG2000 IMAGE Coding System: Part6: Compound Image File Format JPEG2000 part 6 file, PDF: Format Document file, PDF file file. The encoding device according to any one of claims 1 to 8, wherein the image is represented by one file format. An encoding method that encodes an input image to generate a structured document composed of a foreground, a background, and a mask,
An encoding step of assigning a first multivalued image as the foreground, assigning a second multivalued image as the background, assigning a binary image as the mask, and encoding the foreground, the background and the mask, respectively;
Assembling the foreground, the background and the mask encoded by the encoding means according to a predetermined file format to generate a structured document;
The encoding step includes
A first encoding step of encoding an arbitrary image as the first multi-level image by a multi-level encoding method;
A second encoding step of encoding the input image as the second multi-level image by a multi-level encoding method;
And a third encoding step of encoding an image representing white as the binary image by a binary image encoding method.

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