JP2004023164A - Image coding device, image coding method, program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a simple coding by comparing a target pixel with a referential pixel each having considered positional relationship with respect to each other. <P>SOLUTION: In the step S605, a data position of the referential pixel is calculated in response to a layout to be assigned. In the step S608, the coding is performed by exchanging data to a code indicating whether each of pixel values is equal to each other or not, after comparing the target pixel to be coded with the pixel (referential pixel) having considered positional relationship with the target pixel by using the data position of the referential pixel calculated in the step S605. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image encoding device for encoding an image, an image encoding method, a program, and a storage medium.
[0002]
[Prior art]
In order to compress image data, a compression method that uses data continuity in one raster data such as Packbits method or a compression method that uses one line raster data such as Deltarow method. A compression method for performing data compression by using a difference is known. Such a compression method can be implemented relatively easily even when performing compression by software because of its simple processing, and can be realized by a relatively small-scale decoder when decompressing compressed data. Used in many systems.
[0003]
In addition, there are compression methods such as JBIG and JPEG. A compression method such as JBIG or JPEG requires more complicated processing than the Packbits method or the Deltarow method, but can achieve a high compression ratio. However, it is often used for a relatively large-scale system using a dedicated hardware decoder for performing high-speed processing.
[0004]
Other than this, there is a compression method using a combination of the Packbits method and the Deltarow method for compressing image data, and a compression method using a dictionary method such as the LZW method.
[0005]
[Problems to be solved by the invention]
However, with the increase in resolution and gradation of image data, the size of image data to be compressed has been steadily increasing in recent years, and the compression by the Packbits method or the Deltarow method requires a required compression ratio. Is getting harder.
[0006]
On the other hand, the cost of dedicated hardware for JBIG and JPEG is one of the obstacles to lowering the price of products. Further, in the method such as the LZW method, there is a problem in that the processing becomes complicated, so that it takes time to encode and decode an image.
[0007]
The present invention has been made in view of the above problems, and has as its object to provide an image encoding device, an image encoding method, a program, and a storage medium that perform simple encoding.
[0008]
[Means for Solving the Problems]
In order to achieve the object of the present invention, for example, an image encoding device of the present invention has the following configuration.
[0009]
That is, an image encoding apparatus that encodes a second image in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction,
An arrangement relation calculating means for obtaining an arrangement relation between the first images adjacent to each other;
Reference pixel position calculation means for calculating the position of the reference pixel corresponding to the pixel of interest included in the second image using the arrangement relation obtained by the arrangement relation calculation means,
The second image is encoded using the target pixel and the reference pixel.
[0010]
In order to achieve the object of the present invention, for example, an image encoding device of the present invention has the following configuration.
[0011]
That is, image encoding for encoding a second image in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction and a third image in which a plurality of second images are equally arranged in the main scanning direction and the sub-scanning direction. A device,
An arrangement relation calculating means for obtaining an arrangement relation between the first images adjacent to each other;
Reference pixel position calculation means for calculating the position of the reference pixel corresponding to the pixel of interest included in the third image using the arrangement relation obtained by the arrangement relation calculation means,
The third image is encoded using the target pixel and the reference pixel.
[0012]
In order to achieve the object of the present invention, for example, an image encoding device of the present invention has the following configuration.
[0013]
That is, the second image, in which a plurality of the first images are evenly arranged in the main scanning direction and the sub-scanning direction, has a predetermined size with respect to the third image in which the plurality of third images are uniformly arranged in the main scanning direction and the sub-scanning direction. An image encoding device that encodes a fourth image obtained by performing an intermediate process using a matrix,
Means for determining a position of a reference pixel corresponding to a pixel of interest included in the third image using a size of the matrix and a size of the first image,
The third image is encoded using the target pixel and the reference pixel.
[0014]
In order to achieve the object of the present invention, for example, an image coding method of the present invention has the following configuration.
[0015]
That is, an image encoding method for encoding a second image in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction,
An arrangement relation calculating step of obtaining an arrangement relation between the first images adjacent to each other;
A reference pixel position calculating step of obtaining the position of the reference pixel corresponding to the pixel of interest included in the second image using the arrangement relation obtained in the arrangement relation calculating step,
The second image is encoded using the target pixel and the reference pixel.
[0016]
In order to achieve the object of the present invention, for example, an image coding method of the present invention has the following configuration.
[0017]
That is, image encoding for encoding a second image in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction and a third image in which a plurality of second images are equally arranged in the main scanning direction and the sub-scanning direction. The method,
An arrangement relation calculating step of obtaining an arrangement relation between the first images adjacent to each other;
A reference pixel position calculating step of obtaining a position of a reference pixel corresponding to the pixel of interest included in the third image using the arrangement relation obtained in the arrangement relation calculating step,
The third image is encoded using the target pixel and the reference pixel.
[0018]
In order to achieve the object of the present invention, for example, an image coding method of the present invention has the following configuration.
[0019]
That is, the second image, in which a plurality of the first images are evenly arranged in the main scanning direction and the sub-scanning direction, has a predetermined size with respect to the third image in which the plurality of third images are uniformly arranged in the main scanning direction and the sub-scanning direction. An image encoding method for encoding a fourth image obtained by performing an intermediate process using a matrix,
Determining a position of a reference pixel corresponding to a pixel of interest included in the third image using the size of the matrix and the size of the first image,
The third image is encoded using the target pixel and the reference pixel.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail according to preferred embodiments with reference to the accompanying drawings.
[0021]
[First Embodiment]
FIG. 1 shows a color laser beam that decodes encoded data (encoded print data) output by the image encoding apparatus according to the present embodiment and prints the decoded image or character on a recording medium such as paper or OHP. FIG. 2 illustrates a configuration of a printer. In the following, this recording medium is paper, but is not limited to this, and other recording media such as OHP may be used.
[0022]
In FIG. 1, reference numeral 100 denotes a color laser beam printer main body (hereinafter, CLBP) for forming an image of print data developed and supplied by a connected host computer on a recording medium such as recording paper. Reference numeral 104 denotes a controller unit that controls the entire CLBP 100. The controller unit 104 decodes the encoded print data received from the image encoding device, converts the encoded print data into a video signal, and outputs the video signal to the laser driver 110.
[0023]
The laser driver 110 that has received the video signal output from the controller unit 104 performs ON / OFF control of the laser beam 113 emitted from the semiconductor laser 111. The laser beam 113 is swung left and right in accordance with the rotation of the rotary polygon mirror 112, and forms an electrostatic latent image of a print pattern on the electrostatic drum 121. The electrostatic drum 121 is uniformly charged in advance by the charging function of the charging roller 122, and is partially discharged by laser light scanning to form the electrostatic latent image.
[0024]
This electrostatic latent image rotates in the direction of the arrow while maintaining its posture in a predetermined constant direction, and is sequentially contacted with a rotary of cyan (C), magenta (M), yellow (Y), and black (K). The image is developed by the developing devices 124C, 124M, 124Y and 124K. The developed four-color images are multiplex-transferred to the intermediate transfer member 145.
[0025]
A cut sheet recording paper 135 is used as a recording medium. The cut sheet recording paper 135 is loaded into the paper feeder 147 of the CLBP 100, is taken into the apparatus by the paper feed roller 148 and the transport roller 149, and the four color images are transferred from the intermediate transfer body 145. As a result, a full-color image is formed on the cut sheet recording paper 135, and thereafter, the image is fixed by the fixing roller 140 and the pressure roller 141, and output to the outside of the apparatus.
Next, processing of image data in the controller unit 104 will be described. In the present embodiment, the image data is all processed as image data in the image encoding device, and then transferred to the CLBP 100 via an interface described later. The image data at this time is image data of each color of CMYK binary or more, and is encoded (compressed) in the present embodiment. The controller unit 104 expands the received image data and outputs it to the laser driver 110 as a pulse width modulation signal.
[0026]
FIG. 2 is a block diagram showing a basic configuration of each of the CLBP 100 and the image encoding device connected thereto.
[0027]
Reference numeral 3000 denotes an image encoding device, similar to a general computer, wherein a program stored in an external storage device 42 is loaded on the RAM 2 and executed by the CPU 1. Such programs include a device driver for performing a printing process and an application program for displaying the status of the CLBP 100. Other examples include an operating system and an application program that executes document processing in which graphics, images, characters, tables (including spreadsheets and the like) are mixed based on a document processing program and the like.
[0028]
The CPU 1 executes these programs and performs general control of each device connected to the system bus 4. Further, the CPU 1 opens various registered windows based on commands specified by a mouse cursor or the like (not shown) on the CRT 41 and executes various data processing.
[0029]
The RAM 2 functions as a main memory, a work area, and the like for the CPU 1. A keyboard controller (KBC) 5 controls a key input from a keyboard (KB) 40 or a pointing device (not shown). Reference numeral 6 denotes a CRT controller (CRTC), which controls display on the CRT 41. Reference numeral 7 denotes a disk controller (DKC), which is a hard disk (HDD) for storing a boot program, various applications, font data, user files, edit files, and the like, and an external device such as a floppy (registered trademark) disk (FD) or CD-ROM. The access to the storage device 42 is controlled. Reference numeral 9 denotes a parallel input / output controller (PIOC), which executes a bidirectional communication control process with the CLBP 100 via the bidirectional parallel interface 31.
[0030]
When printing is performed, print data is created by the image encoding device 3000 and stored in the external storage device 42 as spool data. In the present embodiment, the spool data is encoded and transmitted to the CLBP 100 via the parallel interface 30. Here, the transfer interface is a bidirectional parallel interface. However, this may be a USB interface or an IEEE 1394 interface.
[0031]
The encoded print data transmitted from the image encoding device 3000 to the CLBP 100 is sequentially written to the RAM 24 via the PIOC 26 in accordance with control processing by the CPU 21 and the control unit 22. The CPU 21 controls each device connected to the system bus 2 and the printing unit 50 by a control program stored in the ROM 23. The RAM 24 is used as a work area of the CPU 21 and mainly as a data reception buffer, that is, a FIFO (First-In First-Out method). The ROM 23 stores programs for controlling the entire CLBP 100, as well as setting data and the like.
[0032]
The encoded data written in the RAM 24 is decompressed by the CPU 21 or the control unit 22, and the decompressed print data is subjected to the print processing described with reference to FIG. Output to the printing unit 50.
[0033]
Next, encoding of an image performed by the image encoding device will be described. FIG. 3 is a diagram showing an example of an image of one logical page (details will be described later) used in the description of this encoding. In the image shown in the figure, a plurality of rectangular texture images by the application program are repeatedly output as background images. In this example, one rectangular texture image has a size of 512 dots in width and 400 dots in height, and shows a state in which images are repeatedly arranged. However, in the following description, the size of the rectangular texture is not limited to this. Absent.
[0034]
FIG. 4 is a diagram showing an image of one page when 4-in-1 layout printing is designated using an application program, and the image is an image to be printed. The image in the figure shows a state in which four logical pages (one logical page is the image of one page shown in FIG. 3) are formed on one physical page. In this case, each logical page output by the application program is reduced to a size of about a quarter, and is arranged in the order, position, and angle according to preset parameters.
[0035]
In the encoding method according to the present embodiment, a pixel to be encoded (target pixel) is compared with a pixel (reference pixel) having a predetermined positional relationship with the target pixel, and whether each pixel value is the same is determined. The encoding is performed by replacing the code with a code indicating the above. FIG. 5 shows a target pixel and a reference pixel. In this embodiment, the reference pixel for the target pixel is determined as follows. That is, for example, when the image shown in FIG. 4 is encoded, the distance from the target pixel to the left end of each adjacent image (repeated interval in FIG. 4) or the right (in the direction parallel to the main scanning direction) The pixel located in () is a reference pixel for the target pixel. Then, the encoding is performed using the target pixel and the reference pixel. Since this encoding method is a known method, its description is omitted here.
[0036]
The positional relationship between the target pixel and the reference pixel can be determined by referring to the above-mentioned parameters, so that the repetition interval can be obtained. Even if adjacent images are rotated, the rotation angle (posture) can also be determined by referring to the above parameters, so that a reference pixel for the target pixel can be obtained. That is, in any case, the reference pixel for the target pixel can be obtained by referring to the parameter indicating the arrangement relationship of each image (each logical page).
[0037]
FIG. 6 is a flowchart of a process performed by the printer driver executed on the image encoding device. In the following description, a case where the image shown in FIG. 4 is encoded will be described as an example, but the encoding target is not limited to the same image.
[0038]
First, in step S601, an image object such as a text / graphics image (the image shown in FIG. 3) is output from the application program and temporarily stored in the RAM 2. In this case, if necessary, a spooling process such as writing to a file is performed.
[0039]
Next, in step S602, it is determined whether a background image has been output. If it is determined that the output has been output, the process proceeds to step S603, and it is determined whether the layout printing is set. In this determination, it is determined whether or not the layout print is set on the property dialog for performing the print setting. When layout printing is set, the RAM 2 also temporarily stores parameters indicating how many logical pages are arranged in a physical page and how.
[0040]
If it is determined that the layout printing is set, the process proceeds to step S604, and the image object temporarily stored in the RAM 2 in step S601 is processed according to the above parameters. That is, when the above parameter indicates a layout in which four reduced logical pages are arranged in a physical page (that is, when the arrangement of each logical page shown in FIG. 4 is specified), in this step, an image is displayed. The object is subjected to reduction processing and arranged at the indicated positions. Further, depending on the above parameters, a rotation process of the image object is also performed.
[0041]
Next, in step S605, a reference pixel data position corresponding to the layout is calculated with reference to the above parameters. The calculation method is as described above. On the other hand, if it is determined in step S602 that the background pattern has not been output, or if it is determined in step S603 that the layout printing has not been set, the process proceeds to step S606, in which a bit map for forming a physical page from the image object is set. Create image data as an image. In the case of a printer driver or the like, color conversion processing such as RBG → CMYK conversion and halftone processing such as dither processing are simultaneously performed. In step S608, the image data thus formed is encoded (compressed) using the reference pixel data position calculated in step S605.
[0042]
As described above, when layout printing is set by the image encoding device according to the present embodiment, the position of the reference pixel with respect to the target pixel can be relatively easily determined by referring to the parameter indicating the layout of layout. , Image data can be encoded using the target pixel and the reference pixel.
[0043]
Further, in the above description, the case of 4-in-1 is shown as an example of the layout print setting. However, the present invention is not limited to this, and may be 8-in-1 or 9-in-1.
[0044]
In the above description, the repetition interval is obtained in the main scanning direction. However, the repetition interval may be obtained in the sub-scanning direction. Further, the main scanning direction and the sub-scanning direction shown in each figure may be opposite directions.
[0045]
[Second embodiment]
In the first embodiment, the repetition interval is obtained for each logical page. However, since the same image (background image) is included in a logical page, the size of the background image may be used as the repetition interval. In the present embodiment, the repetition interval is obtained for each background image. Note that the basic configuration of the image encoding device according to the present embodiment is the same as that of the first embodiment. Further, in the following description, one logical page uses the same one shown in FIG. 3 as in the first embodiment.
[0046]
FIG. 7 is a diagram illustrating an image of one page when 2-in-1 layout printing is designated using an application program. In this case, each background image output from the application program is arranged to be reduced by half and rotated by 270 degrees at the same time. That is, the image output in the portrait is arranged in the landscape. Therefore, in this case, as for the rectangular repetition interval, a height of 200 dots in the short side direction of the sheet, which is the main scanning direction, (1/2 of the original height of 400 dots of the rectangle) is used. It is assumed that the size of the background image is known in advance, and the height after the change due to the above-described reduction and rotation is also obtained using the known size.
[0047]
The image encoding process according to the present embodiment is a process of obtaining a reference pixel using the repetition interval instead of the above-described parameters in the flowchart illustrated in FIG.
[0048]
[Third Embodiment]
In the above embodiment, the position of the reference pixel is calculated using the size of the logical page and the size of the background image. However, when the halftone processing using the dither pattern is performed on the physical page, this dither Depending on the size of the pattern and the size of the background image, the reference pixel data position may be calculated to be the least common multiple thereof.
[0049]
For example, assuming that the size of the dither pattern is 16 dots in width and the width of the background image is 200 dots, the background image, which was originally the same image, may not become the same pattern by performing dither halftone processing. FIG. 8 shows this state. FIG. 8 is a diagram showing each background image after the halftone processing.
[0050]
In the figure, the regions 701 to 704, which were originally the same image, have the same region 701 and 703 and the same region 702 and 704 by halftone processing. Therefore, in such a case, it can be obtained by setting the position of the reference pixel data at 400 dots left.
[0051]
[Other embodiments]
An object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or the apparatus stores the storage medium in the storage medium. Needless to say, this can also be achieved by reading and executing the programmed program code.
[0052]
In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
[0053]
As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. I can do it. When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. It goes without saying that a case where a part of the actual processing is performed and the function of the above-described embodiment is realized by the processing is also included.
[0054]
Further, after the program code read from the storage medium is written into a memory provided on a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that a CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0055]
【The invention's effect】
As described above, an object of the present invention is to perform simple encoding.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an image or a character decoded by decoding encoded data (encoded print data) output by an image encoding apparatus according to a first embodiment of the present invention on a recording medium such as paper or OHP. FIG. 2 is a diagram illustrating a configuration of a color laser beam printer that prints a color image.
FIG. 2 is a block diagram illustrating a basic configuration of each of a CLBP 100 and an image encoding device connected thereto.
FIG. 3 is a diagram illustrating an example of an image of one page to be encoded, which is used for describing encoding performed by the image encoding device according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating an image of one page when 4-in-1 layout printing is designated using an application program.
FIG. 5 is a diagram showing a target pixel and a reference pixel.
FIG. 6 is a flowchart of a process performed by a printer driver executed on the image encoding device according to the first embodiment of the present invention.
FIG. 7 is a diagram illustrating an image of one page when 2-in-1 layout printing is designated using an application program according to the second embodiment of the present invention.
FIG. 8 is a diagram showing each background image after halftone processing.

Claims (13)

An image encoding apparatus for encoding a second image in which a plurality of first images are uniformly arranged in a main scanning direction and a sub-scanning direction,
An arrangement relation calculating means for obtaining an arrangement relation between the first images adjacent to each other;
Reference pixel position calculation means for calculating the position of the reference pixel corresponding to the pixel of interest included in the second image using the arrangement relation obtained by the arrangement relation calculation means,
An image encoding device, wherein the second image is encoded using the target pixel and the reference pixel. The arrangement relation calculating means obtains the arrangement relation of each adjacent first image using a parameter indicating the arrangement relation of the first image in the second image. 2. The image encoding device according to 1. 3. The image coding apparatus according to claim 2, wherein the arrangement relation calculating unit obtains an interval between corresponding portions in each of the first images adjacent to each other. 3. The image coding apparatus according to claim 2, wherein said arrangement relation calculating means calculates a rotation angle of each of the first images adjacent to each other. An image encoding device that encodes a second image in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction, and a third image in which a plurality of second images are equally arranged in the main scanning direction and the sub-scanning direction. So,
An arrangement relation calculating means for obtaining an arrangement relation between the first images adjacent to each other;
Reference pixel position calculation means for calculating the position of the reference pixel corresponding to the pixel of interest included in the third image using the arrangement relation obtained by the arrangement relation calculation means,
An image encoding apparatus, wherein the third image is encoded using the target pixel and the reference pixel. A second image, in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction, is further divided into a matrix of a predetermined size with respect to a third image in which a plurality of uniform images are arranged in the main scanning direction and the sub-scanning direction. An image encoding device that encodes a fourth image obtained by performing an intermediate process using the image encoding device,
Means for determining a position of a reference pixel corresponding to a pixel of interest included in the third image using a size of the matrix and a size of the first image,
An image encoding apparatus, wherein the third image is encoded using the target pixel and the reference pixel. 7. The method according to claim 6, wherein the means obtains, as a reference pixel position, a pixel at a position shifted from the pixel of interest by a least common multiple of the size of the matrix and the size of the first image. Image coding device. An image encoding method for encoding a second image in which a plurality of first images are uniformly arranged in a main scanning direction and a sub-scanning direction,
An arrangement relation calculating step of obtaining an arrangement relation between the first images adjacent to each other;
A reference pixel position calculating step of obtaining the position of the reference pixel corresponding to the pixel of interest included in the second image using the arrangement relation obtained in the arrangement relation calculating step,
An image encoding method, comprising: encoding the second image using the target pixel and the reference pixel. An image encoding method for encoding a second image in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction, and a third image in which a plurality of first images are equally arranged in the main scanning direction and the sub-scanning direction. So,
An arrangement relation calculating step of obtaining an arrangement relation between the first images adjacent to each other;
A reference pixel position calculating step of obtaining a position of a reference pixel corresponding to the pixel of interest included in the third image using the arrangement relation obtained in the arrangement relation calculating step,
An image encoding method, comprising: encoding the third image using the target pixel and the reference pixel. A second image, in which a plurality of first images are uniformly arranged in the main scanning direction and the sub-scanning direction, is further divided into a matrix of a predetermined size with respect to a third image in which a plurality of uniform images are arranged in the main scanning direction and the sub-scanning direction. An image encoding method for encoding a fourth image obtained by performing an intermediate process using
Determining a position of a reference pixel corresponding to a pixel of interest included in the third image using the size of the matrix and the size of the first image,
An image encoding method, comprising: encoding the third image using the target pixel and the reference pixel. A program for causing a computer to function as the image encoding device according to any one of claims 1 to 7. A program for causing a computer to execute the image encoding method according to claim 8. A storage medium for storing the program according to claim 11.

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