JPH09200535A - Image processing apparatus and method - Google Patents

Abstract

(57) Abstract: Since conversion of image data form from index color data to intermediate expression color data needs to be performed pixel by pixel, the conversion process takes time. A CPU1 determines whether or not converted data corresponding to palette data designated by index color data is stored in a cache area of a RAM3, and the converted data is stored. In this case, the processed data is read from the cache area. If not, the designated palette data is read from the color palette stored in the RAM 3, the read palette data is converted, and the converted data is stored in the cache area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and a method thereof, and more particularly, to an image processing apparatus and a method thereof for converting a form of image data.

[0002]

2. Description of the Related Art In the case of transmitting a color image or storing a color image in a storage medium, a data format that requires a relatively small amount of data, for example, 8-bit index color data is often used. Then, the index color data is converted into 8-bit RGB color image data by a predetermined color palette and displayed on a monitor or the like.

Further, in an ink jet printer, a ferroelectric liquid crystal display (FLCD), etc., called a binary color output device, multi-valued color image data is subjected to pseudo halftone processing such as dither processing or error diffusion method. An image is formed based on the obtained binary color image data. Therefore, when outputting a color image represented by index color data using a binary color output device, the index color data is once converted into multi-valued color data and then pseudo halftone processing is performed. It will be binarized.

Similarly, when a color image represented by index color data is output using a grayscale device (for example, a laser beam printer capable of expressing gradation), the index color data is once converted into grayscale data. After conversion to, the pseudo-halftone process is performed and binarization is performed.

The above conversion process is performed for each pixel from the palette data indicated by the index color data to the multivalued RGB.
The intermediate representation color data, which is data (or grayscale data), is obtained.

[0006]

However, the above-mentioned technique has the following problems. In other words, since the conversion of the image data form from the index color data to the intermediate representation color data needs to be performed pixel by pixel, there is a problem that the conversion process takes time.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide an image processing apparatus and method capable of speeding up the processing for converting the form of image data.

[0008]

The present invention has the following configuration as one means for achieving the above object.

The image processing device according to the present invention stores the data read from the color palette and processed, and the palette data designated by the input image data, and stores the processed data. And storing the processed data corresponding to the designated pallet data in the storage means, the processing means reads the processed data from the storage means, and specifies the processed data. When the processed data corresponding to the palette data is not stored in the storage means, the specified palette data is read from the color palette and the read palette data is processed.

Further, the image processing method according to the present invention comprises a determining step of determining whether or not processed data corresponding to the palette data designated by the input image data is stored in the storage means. Based on the judgment result obtained in the judgment step, based on the processing step of processing the specified pallet data, and the judgment result,
A storage step of storing the data processed in the processing step in the storage means.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Structure] FIG. 1 is a block diagram showing a schematic structure of a host computer 10 which executes software for realizing an image processing system according to an embodiment of the present invention.

The CPU 1 controls the entire host computer 10 via the main bus 7, and also has an input device 11 (for example, image scanner or storage device) and an output device 12 (for example, printer or printer) connected to the outside of the host computer 10. Monitor) via interfaces (I / F) 4,5.
In other words, the CPU 10 uses the interface (KBD I / F) 6 to input (such as the keyboard 8 and pointing device).
9) Performs a series of processes such as image input, image processing, and image output control according to the instructions input from 9).

The ROM 2 stores the boot program of the CPU 1 including the BIOS of the host computer 10 and the like. RAM3
The CPU 1 loads the OS and other application programs on the RAM 3 and executes them. This application program includes an image processing program according to the present invention. Further, the RAM 3 is used as a work memory when the CPU 1 performs various kinds of arithmetic processing and also as an area in which the CPU 1 loads data necessary for the arithmetic operation. Various data including the above-mentioned OS, application programs, and image data are supplied from a storage medium such as FD, HD, CD-ROM, magneto-optical disk, or a communication line via a predetermined interface.

[Structure of Image Data] Before explaining the image processing according to the present invention, the structure of data used in the image processing will be described. Note that data, arrays, variables, flags, etc. described below exist in a memory such as the RAM 3 unless otherwise specified.

FIG. 2 is a diagram showing an example of the structure of the image data stored in the storage area of the input image data, and is an array of, for example, 8-bit palette index data designating the palette data. Below, this data is data [] (the number of elements is n +
Expressed as 1). Here, the number of elements n + 1 is equal to the number of pixels of the input image data.

FIG. 3 is a diagram showing an example of the structure of palette data stored in the palette storage area. The palette data is, for example, an array of RGB values each having 8 bits and a total of 24 bits. Less than,
This data is represented by palette [] (the number of elements is m + 1). Here, the number of elements m + 1 is equal to the number of color palettes, and is 256 when 8-bit index color data is handled. The palette data is not always stored in the palette storage area of RAM3. For example, the palette data stored in the external storage device or the ROM 2 described above can be used, or the palette data input together with the image data can be used.

FIG. 4 is a diagram showing an example of the structure of cache data stored in the primary cache area. The primary cache data is an array of RGB values as in FIG. Hereinafter, this data is represented by cash1 [] (the number of elements is m + 1).

FIG. 5 is a diagram showing an example of the structure of cache data stored in the secondary cache area. The secondary cache data is intermediate representation color data used before the binarization process.
It is an array including a flag indicating that the calculation has been completed. Less than,
This data is represented by cash2 [] (the number of elements is m + 1). Also, i
The intermediate representation color data of the second array cash2 [i] is cash2 [i] .val
Then, the calculated flag is represented by cash2 [i] .flag.

FIG. 6 is a view showing an example of the structure of image data stored in the storage area for intermediate image data. The intermediate image data is an array of intermediate expression color data. Below, this data
It is represented by tensity [] (the number of elements is n + 1).

[Image Processing] Next, the processing of converting the index color data into the intermediate expression color data using the primary and secondary caches will be described.

7 and 8 are flowcharts showing an example of the procedure of the image processing according to the present invention, which is executed by the CPU 1.

First, in step S102, the flag init_flag is checked. The init_flag is a flag that indicates that cash1 [] is in the initial state by "0" when the program of this processing is loaded into the RAM3 and first executed. This is because, in general, when a program is called multiple times, the timing and the number of times are often unknown on the called program side. Therefore, the flag init_flag
Indicates the initial state of cash1 []. That is, step S10
By determining the state of init_flag in 2, the palette []
Determines whether the data in should be copied to cash1 []. If init_flag = '0', then in step S103 i
Set '1' to nit_flag. From this time onward,
When this program is called, the process proceeds to step S104. If you want to change the palette data already stored in cash1 [], set init_flag to "0" before calling this program.

In step S104, the loop variable i is set to 0, and it is determined in steps S105 to S107 whether all the data of palette [] and cash1 [] are equal. And palette
If there is even one [i] ≠ cash1 [i], then in step S108, p
Copy all the data in alette [] to cash1 [], step S10
In 9, the flag1 is set to '1' to indicate that the cash1 [] data has been rewritten. On the other hand, palette [] = cash
If it is 1 [], then in step S110 flag0 is set to "0" to indicate that the data in cash1 [] has not been rewritten.

In this way, all of the palette data is RA
When stored in cash1 [] allocated on M3, when using palette data stored in an external storage device that uses a relatively low-speed storage medium such as a hard disk, CD-ROM, magneto-optical disk, floppy disk, etc. In addition, the access to the palette data can be speeded up.

Then, in step S201, the state of flag1 is checked. If flag1 = '1', all calculated flags flag of cash2 [] are cleared to '0' in step S202. Next, in step S203, 0 is set to the loop variable i, and step S204
To execute the loop of S212.

That is, in step S204, the palette index data of data [i] is substituted into the variable index, and step S
In 205, it is determined whether or not '1' is set in cash2 [index] .flag. This cash2 [index] .flag is not calculated when cash2 [index] .val is "0", and cas when it is "1".
h2 [index] .val means calculated.

If cash2 [index] .val = '0',
In step S206, the intermediate expression color data is calculated using the RGB value of cash1 [index], and the calculated intermediate expression color data is set to the variable co.
Substitute in l. The format of this intermediate representation color data depends on the data to be output. For example, when outputting binary color data, the halftone expression color is also represented by multivalued RGB data (for example, 8 bits each for a total of 24 bits), so cash1 [ind
The RGB value of [ex] can be used as it is to represent the intermediate expression color, but when outputting grayscale data or binary monochrome data, the intermediate expression color must be represented by 8-bit grayscale data Gr, for example, It is calculated using the following formula. Gr = (α ・ R + β ・ G + γ ・ B) (1) where 0 <α <1, 0 <β <1, 0 <γ <1, α + β + γ = 1 For example α = 0.3 , β = 0.6, γ = 0.1

Next, in step S207, the intermediate expression color data of the variable col is stored in cash2 [index] .val, and in step S208
Set '1' to cash2 [index] .flag and set cash2 [inde
After indicating that [x] .val has been calculated, step S210
Proceed to.

On the other hand, when cash2 [index] .val = '1', intermediate representation color data is extracted from cash2 [index] .val and assigned to the variable col in step S209.

Subsequently, in step S210, the intermediate expression color data of the variable col is stored in intensity [i], and in step S211, it is determined whether or not the end of the input image data, that is, i = n. If i ≠ n, the process proceeds to step S212, the variable i is incremented, and the process returns to step S204.

On the other hand, when i = n, it means that all the palette index data of data [] have been converted into the intermediate expression color data. Therefore, in step S213, all the data of intensity [] is output in a form suitable for the output application. Convert to. That is, when outputting image data to a full-color device such as a color monitor or film recorder, multivalued RGB data,
In other words, all the data of intensity [] should be output as it is (or the bit depth adjusted). When outputting to a full-color device such as a color laser beam printer, all the data of intensity [] should be converted to multi-valued CMY or CMYK data (and the bit depth should be adjusted if necessary) before output. .

When the image data is output to a binary color output device such as an FLCD, a binarization method (for example, simple binarization or dithering) according to the characteristics of the device or the purpose of the binary image data is used. , Error diffusion, etc.)
Binary color image data obtained by binarizing all data of nsity [] may be output. When outputting to a binary color device such as an inkjet printer, after converting all intensity [] data to multi-valued CMY or CMYK data, binarization according to the characteristics of the device and the use of binary image data The binary color image data binarized by the method may be output.

Furthermore, when outputting to a gray scale monitor or the like, the gray scale data of intensity [] may be output as it is (or after adjusting the bit depth). When outputting to a multi-tone laser beam printer or the like, grayscale data of intensity [] may be converted to density data and output as it is (or with bit depth adjusted). Although detailed description is omitted, step S2
In 13, gamma correction according to the characteristics of the output device,
It goes without saying that image processing such as gradation correction and color reproduction range compression is performed on the image data as necessary.

As described above, according to this embodiment, the palette data is cached in the primary cache area allocated to the RAM3 or the like, and the intermediate expression color data calculated from the cached palette data is allocated to the RAM3 or the like secondary cache area. Since the palette index data is already calculated, it is not necessary to newly calculate the intermediate expression color data, and it is only necessary to read the intermediate expression color data from the secondary cache area. Therefore, it is possible to reduce the number of times the intermediate expression color data is calculated for at least one input image data (index color data), and the number of times the intermediate expression color data is calculated for a plurality of input image data unless the palette data is changed. Can be reduced. That is, the index color data is converted into a multivalued RG by the number of times the intermediate expression color data is calculated.
It is possible to speed up the process of converting to B data or grayscale data.

[0036]

Second Embodiment Hereinafter, an image processing apparatus according to a second embodiment of the present invention will be described. In the second embodiment,
The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the above-described first embodiment, the palette data palette [] is compared with the primary cache data cash1 [], and if there is at least one different data, palett
An example of copying all data of e [] to cash1 [] has been explained,
In the second embodiment, only the data that does not match is paletted.
Copy from te [] to cash1 [].

FIG. 9 is a flow chart showing an example of the image processing procedure of the second embodiment, which corresponds to FIG. 7 of the first embodiment. That is, in step S105, cash1 [i] ≠ palett
If it is e [i], the process does not proceed to step S108 but step S3.
In 07, the palette data of palette [i] is copied to cash1 [i], cash2 [i] .flag is set to "0" in step S308, and the process proceeds to step S106.

By doing so, even when a part of cash1 [] is rewritten, the intermediate representation color data may be calculated only when the flag of cash2 [] is '0', and the intermediate representation color data can be calculated more than in the first embodiment. The number of times expression color data is calculated can be reduced.

[0040]

Third Embodiment Hereinafter, an image processing apparatus according to a third embodiment of the present invention will be described. In the third embodiment,
The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The standard color palette prepared for the operating system and application software is
Different colors are preset for each palette. But,
The same color may be set in different palettes in the color palette created by the user and the color palette obtained by modifying the standard color palette by the user.

The above-described embodiment does not consider the case where the same color is set in such different palettes. In the third embodiment, when there are different palettes in which the same color is set, the palette index data of the pixels pointing to those palettes are set to the same value and updated to point to one palette.

FIG. 10 is a flow chart showing an example of the procedure of the image processing of the third embodiment, which is a process of updating the input image data executed after step S109 or S110 shown in FIG. 7 (or FIG. 9). An example is shown.

First, the loop variable j is initialized to 1 in step S501, and the palette index data of data [j] is substituted into the index counter p1_index in step S502.
Next, in step S503, the loop variable i is initialized to 0, and in step S504, the palette index data of data [i] is assigned to the index counter p2_index.

Then, in step S505, p1_index and p2_ind
Ex is compared, and if they are equal (that is, they point to the same palette), the process proceeds to step S509. Also, p1_index ≠ p2_i
In the case of ndex, in step S506, the RGB data of cash1 [p1_index] is assigned to the variable rgb1, and the RGB data of cash1 [p2_index] is assigned to the variable rgb2. Next, in step S507, rgb1 and
rgb2 is compared, and if they are equal (that is, the palettes are different but the same color), the value of p2_index is stored in data [j] in step S508, and then the process proceeds to step S511. If rgb1 ≠ rgb2, the variable i is incremented in step S509, the variables i and j are compared in step S510, and if i <j, the process returns to step S504, and if not, the process proceeds to step S511.

In step S511, the variable j is incremented, the variable i is compared with the pixel number n in step S512, and if j> n, the process returns to step S502, and if not, the process proceeds to step S201 shown in FIG. .

By doing so, even when the same color is set in different palettes, the palette index data of the pixels pointing to those palettes are set to the same value,
Since it can be updated to point to one palette, the number of calculations of intermediate expression color data can be reduced and the processing speed can be increased.

[0048]

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (for example, a copying machine) Machine, facsimile machine, etc.).

Further, an object of the present invention is to supply a storage medium having a program code of software for realizing the functions of the above-described embodiment to a system or apparatus, and to supply the computer (or CPU or M or CPU of the system or apparatus).
Needless to say, this can also be achieved by the PU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Examples of the storage medium for supplying the program code include a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM,
CD-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) running on the computer based on the instruction of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Furthermore, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that a case where the CPU included in the function expansion card or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

In each of the above-described embodiments, an example has been described in which the index color data is 8 bits, the RGB data is 8 bits each and the total is 24 bits, and the gray scale data is 8 bits. However, the present invention is not limited to this. However, it is possible to handle image data of any bit depth such as 4-bit index color data, RGB data of 15-bit total of 15 bits, gray-scale data of 4-bit or 2-bit. Further, the palette data and the intermediate expression color data are not limited to RGB data, and may be CMY or CMYK data.

Further, in the above-described embodiment,
In step S206 shown in FIG. 8, an example in which the index color data is converted into the corresponding grayscale data obtained from the palette data of, for example, each RGB 8-bit or the palette data has been described. By changing the color, it is possible to convert the palette data into RGB 8-bit palette data, and to reduce the bit width of the data to RGB 5-bit (or 4-bit or 2-bit grayscale), for example.

When the present invention is applied to the above-mentioned storage medium, the storage medium stores the program code corresponding to the above-mentioned flow chart. Briefly, in the memory map example of FIG. Each module shown will be stored in the storage medium. That is, at least the program code of each module of “determination”, “processing” and “storing” may be stored in the storage medium.

[0055]

As described above, according to the present invention,
It is possible to provide an image processing apparatus and method for speeding up the process of converting the form of image data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a host computer that executes software that realizes an image processing system according to an embodiment of the present invention;

FIG. 2 is a diagram showing a structural example of image data stored in a storage area of input image data,

FIG. 3 is a diagram showing a structure example of palette data stored in a palette storage area;

FIG. 4 is a diagram showing a structure example of cache data stored in a primary cache area;

FIG. 5 is a diagram showing a structure example of cache data stored in a secondary cache area;

FIG. 6 is a diagram showing an example of the structure of image data stored in a storage area of intermediate image data;

FIG. 7 is a flowchart showing an example of an image processing procedure according to the present invention;

FIG. 8 is a flowchart showing an example of an image processing procedure according to the present invention;

FIG. 9 is a flowchart showing an example of the procedure of image processing according to the second embodiment of the present invention,

FIG. 10 is a flowchart showing an example of the procedure of image processing according to the third embodiment of the present invention,

FIG. 11 is a diagram showing an example of a memory map of a storage medium storing a program code according to the present invention.

Claims (13)

[Claims] 1. Storage means for storing processed data read from a color palette; processing means for processing palette data designated by input image data and storing the processed data in the storage means. The processing means reads the processed data from the storage means when the processed data corresponding to the designated palette data is stored in the storage means, and performs the processing corresponding to the designated palette data. Image data is stored in the storage means, the specified palette data is read from the color palette and the read palette data is processed. 2. The image processing apparatus according to claim 1, further comprising a binarizing unit that binarizes the data processed by the processing unit. 3. The image processing apparatus according to claim 2, further comprising a binary color output device that outputs an image based on the data binarized by the binarizing unit. 4. The image processing apparatus according to claim 1, further comprising a halftone processing unit that performs pseudo halftone processing on the data processed by the processing unit. 5. A binary color output device for outputting an image based on the data subjected to pseudo halftone processing by the halftone processing means.
The image processing device described in. 6. The image processing apparatus according to claim 1, wherein the processing unit converts the palette data read from the color palette into grayscale data. 7. The storage means for storing the color palette is further provided, and if the color palette stored in the storage means is different from the color palette to be processed, the processing means uses the color palette to be processed. 7. The image processing apparatus according to claim 1, wherein the storage unit is updated. 8. The storage device further comprises storage means for storing the color palette, wherein the processing means compares the color palette stored in the storage means with a color palette to be processed, and obtains corresponding palette data. 7. The image processing device according to claim 1 or 6, wherein when different, the palette data in the storage unit is updated to the palette data to be processed. 9. The storage device further comprises storage means for storing the input image data, and the processing means has the same different palette data designated by different unit data constituting the input image data stored in the storage means. 7. In the case of, the image processing device according to claim 1 or 6, wherein the unit data are the same. 10. A determination step of determining whether or not processed data corresponding to palette data designated by input image data is stored in the storage means, and a determination result obtained in the determination step. An image processing method comprising: a processing step of processing the designated palette data based on the determination result; and a storage step of storing the data processed in the processing step in the storage means based on the determination result. 11. The processing step reads the processed data from the storage means when the determination result indicates that the processed data corresponding to the designated pallet data is stored in the storage means. 11. If not, the image processing method according to claim 10, wherein the designated palette data is read from the color palette and the read palette data is processed. 12. The storage step, when the determination result indicates that the processed data corresponding to the designated palette data is not stored in the storage means, stores the data processed in the processing step in the storage means. 11. The image processing method according to claim 10, wherein the image is stored. 13. A computer-readable memory that stores image processing program code, and determines whether or not processed data corresponding to palette data designated by input image data is stored in the storage means. Based on the code of the determination step and the determination result obtained in the determination step, the code of the processing step that processes the designated pallet data, and based on the determination result, the data processed in the processing step is stored. A computer readable memory having the code of the storing step stored in the means.