JP3022143B2 - Conversion device for RGB data to CMY data - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for converting RGB data into CMY data which converts RGB image data into CMY format image data suitable for printing.

[0002]

2. Description of the Related Art RGB which is a form of expression in a luminance signal
(R; Red, G; Green, B; Blue) format image data in CMY (C; Cyan, M; Magenta, Y; Yellow) format, which is an expression format using density signals for printing Conventionally, when converting into data, CMY data is obtained by performing an arithmetic processing by software or hardware on RGB data of each pixel for all pixels of image data at the time of actual conversion processing (for example, Japanese Unexamined Patent Publication (Kokai) No. 63-302671,
No. 284059).

However, in such a configuration in which the arithmetic processing is performed at the time of actual conversion to convert the RGB data into the CMY data, the arithmetic processing time is a bottleneck in the case of an enormous amount of color images such as several megabytes to several hundred megabytes. Therefore, there is a problem that CMY data cannot be generated quickly.

Accordingly, for example, Japanese Patent Application Laid-Open No. 63-278850.
As shown in the publication, when the RGB data is not the RGB intensity itself but a format representing one entry of the pallet table in which the RGB intensity is registered, prior to the actual conversion, the RGB intensity of each entry of the pallet table is converted. A technique has been proposed in which CMY intensities are obtained from the data and set in a color conversion table, and at the time of actual conversion, the RGB data is converted to CMY data by referring to the color conversion table, and then color correction is performed by a color correction program. ing.

[0005]

According to the configuration using the color conversion table as described above, the RGB data is
Since it is not necessary to execute the arithmetic processing for converting to Y data at the time of actual conversion, the conversion processing time is reduced.

However, the prior art disclosed in Japanese Patent Application Laid-Open No. 63-288850 can be applied only when the RGB data has a format not representing the RGB intensity itself but one entry of a pallet table.
In the case of expressing the intensity itself, it was necessary to convert it into CMY intensity by a color conversion program at the time of the actual conversion process. Also, the CM converted with reference to the color conversion table
When color correction is performed on the Y data, it is necessary to sequentially perform the correction using a color correction program.

The present invention has solved such a conventional problem. The purpose of the present invention is to perform color correction only by referring to a conversion table, even when the RGB data has a format indicating the RGB intensity itself. It is an object of the present invention to provide an apparatus for converting RGB data into CMY data so as to obtain CMY data.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method of forming RGB images of all predetermined patterns.
Maskin set for the data according to the printing environment
CMY data that has been subjected to color correction based on the
Conversion table for conversion and the RGB data requested for conversion.
Data, masking set according to the printing environment
Generate CMY data that has been subjected to color correction based on the coefficients
Conversion table creation means for setting the conversion table in the conversion table
When the RGB data to be converted is generated, the RGB
CMY data corresponding to the data from the conversion table
Search and when valid CMY data is obtained, the CMY
Data is output as a conversion result, and valid CMY data
If not obtained, convert to the conversion table creation means
Requests conversion by notifying the target RGB data, and
Conversion means for outputting the converted CMY data as a conversion result;
And the conversion table creation means has a predetermined
Of all the RGB data patterns
RGB data that has not been processed
Color correction based on the previously set masking coefficients.
Generated CMY data and set it in the conversion table
Processing during the operation of the conversion unit or the conversion unit
Is performed during the non-operation of.

Further, the conversion table according to the present invention .
Represents the values of the three components R, G, and B that compose the RGB data.
The combined value is used as an index of CMY data, and C
A configuration for holding a valid bit indicating the validity of MY data
It is characterized by having.

[0010]

[0011]

[0012]

[0013]

[0014]

In the conversion device into CMY data of the RGB data of the effects of the present invention, for all RGB data defined Me pre, the CMY data is subjected to color correction based on the masking coefficients set according to the printing environment to hold
When the RGB data to be converted is generated, the conversion means searches the conversion table for CMY data corresponding to the RGB data to be converted, and converts the CMY data obtained by the search. Output as conversion result. However, if the conversion table creation is not completed,
If you cannot start the exchange at all,
Conversion means, the RGB data to be converted
Data, the CMY data corresponding to the RGB data
Is retrieved from the conversion table, and valid CMY data is
When obtained, output the CMY data as a conversion result
If valid CMY data cannot be obtained,
Pass the RGB data to be converted to the conversion table
To request conversion, and convert the obtained CMY data to the conversion result
Output as In addition, the conversion table creation means
Still strange among all defined RGB data patterns
Printing environment for RGB data that has not been replaced
Color correction based on the masking coefficient set according to the
Generates the CMY data applied in
During the operation of the conversion means or during the conversion.
The conversion table can be quickly executed by performing while the means is not operating.
Is completed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will now be described in detail with reference to the drawings.
A technology (hereinafter, referred to as a prerequisite technology) will be described.

FIG. 1 is a block diagram of the prerequisite technology of the present invention.
1 is a center (host computer) and 2 is a terminal connected to the center 1 via a communication line 3. This terminal 2
Is a device for reading a color image recorded on a medium 4 such as a color film and sending the color image to the center 1 through the communication line 3. The color image is scanned and digital RGB data (R component An 8-bit signal indicating the intensity of the G component, an 8-bit signal indicating the intensity of the G component,
A scanner 21 that outputs an 8-bit signal indicating the intensity of the B component), and a transmission unit 22 that transmits the output of the scanner 21 to the center 1.

The scanner 21 outputs an 8-bit signal for each of the R, G, and B components. However, since the resolution of the scanner itself is 128 gradations, each component is represented by a decimal notation of 0, 2, and 4. ,.., 254 are output.

On the other hand, the center 1 receives RGB signals from the terminal 2.
A receiving unit 11 for receiving data, a table 12 for holding the received RGB data, a conversion unit 13 realized by a conversion program or the like for executing a conversion process on the RGB data stored in the table 12, A table 14 for storing the conversion result of the means 13; a printing means 15 for performing color printing in accordance with the contents of the table 14; a conversion table 16 to which the conversion means 13 refers at the time of conversion; Means 17
And an input device 1 for giving a masking coefficient used for conversion start and color correction to the conversion table creation means 17.
8.

The conversion table creating means 17 generates an RGB data which is expected to appear.
B data generation unit 171, a table 172 for holding the generated RGB data, and individual Rs in the table 172.
A conversion unit 173 composed of a conversion program for converting RGB data into CMY data by a known method using the fact that RGB has a complementary color relationship with CMY, and CMY data generated by this conversion unit 173 Input device 18
A known color correction based on a masking coefficient (H
DC correction), and a K component (black component) is generated from the color-corrected CMY data output from the color correction unit 174 and added thereto. And a K creation adding unit 175 set in the conversion table 16.

In this base technology, the conversion table creating means 17 is started from the input device 18 prior to the generation of the RGB data to be converted.
In the RGB data generation unit 171, the RGB data (r0, g0, b0), (r
1, g1, b1),..., (RP, gP, bP). In this case, the R, G, and B components are all 128 from the terminal 2.
Since RGB data expressed in gradation is sent out,
In the RGB data generation unit 171, the RGB components (0, 0,
0), (0, 0, 2), ..., (254, 254, 25
A total of 128 ³ pieces of RGB data having 4) are generated.

After these RGB data are stored in the table 172, the conversion unit 173 and the color correction unit 17 one by one.
The CMY data processed by the 4, K creation / addition unit 175 is set in the conversion table 16. Here, the conversion table 16 has an entry assigned with an index I from 0 to 128 ^3, and the conversion target RGB
Assuming that the value of the R component of the data is Ri, the value of the G component is Gi, and the value of the B component is Bi, the CMY data as the conversion result of the RGB data is set in the following index entry of the conversion table 16. You. Index I = (Ri / 2) × 128 ² + (Gi / 2) × 128 + Bi / 2 (1)

FIG. 2 shows the relationship between the value of the RGB component of each RGB data and the value of the index storing the CMY data corresponding to the RGB data.

After the creation of the conversion table 16 by the conversion table creating means 17 is completed, the RGB data (R0, G
0, B0), (R1, G1, B1),..., (Rx, G
When (x, Bx) is transmitted, they are received by the receiving unit 11, set in the table 12, and the conversion process by the conversion unit 13 is started.

FIG. 3 shows an example of the processing of the conversion means 13.
The conversion means 13 first focuses on the first RGB data (R0, G0, B0) of the table 12 (S1), finds the index I from the values of the respective RGB components by the above formula (1) (S3), Then, the CMY data having the index I is read from (S4), and this is output to the table 14 as a conversion result (S5). Then, returning to step S1, the second RGB data (R1, G1,
The same processing as described above is repeated for B1). If it is determined in step S2 that the execution has been completed up to the last RGB data (Rx, Gx, Bx), the processing is terminated.
After that, the CMY data in the table 14 is given to the printing unit 15 and color printing is performed.

The RG transmitted from terminal 2 in this way
Since the process of converting the B data into the CMY data is replaced with the process of searching the conversion table 16, high-speed conversion can be realized.

[0026]

Next, an embodiment of the present invention will be described.
FIG. 4 is a block diagram of one embodiment of the present invention, wherein the same reference numerals as in FIG. 1 indicate the same parts, 13B is a conversion means, 16A is a conversion table, and 17A is a conversion table creation means. In this embodiment, the conversion by the conversion means 13B can be started even if the creation of the conversion table 16A is not completed.

In the conversion table 16A, an entry corresponding to each index has a valid flag VF. When valid CMY data is set, the valid flag VF is turned on.
If (1) is set and valid CMY data is not set, the valid flag VF is OFF (0).

Upon receiving the activation from the receiving unit 11, the conversion unit 13B first focuses on the first RGB data (R0, G0, B0) of the table 12, as shown in FIG. 5 (S1).
1) An index I is obtained from the values of the RGB components according to the above equation (1) (S13), and the conversion table 16A
Then, the CMY data having the index I is read out together with the valid flag VF (S14). Then, it is determined whether or not the read valid flag VF is ON (S15),
If it is ON, the read CMY data is output to the table 14 as a conversion result (S16), and the process returns to step S1 to repeat the same processing for the second and subsequent RGB data.

If the read valid flag VF is not ON, the index I is notified and a conversion is requested to the conversion table creation means 17A (S17). When the conversion table creation means 17A returns a notification of the conversion completion, (S1
(YES at 8), returning to step S14 to read out the CMY data of index I again. As will be described later, the conversion table creation unit 17A, which is notified of the index I and is requested to perform the conversion, generates CMY data corresponding to the RGB data related to the index I, and generates the conversion table 16A.
After the conversion is completed, the validity flag VF is turned on and the conversion completion is notified to the conversion means 13B. Therefore, the conversion means 13B reads out the CMY data again after the conversion is completed, so that the valid CMY data can be obtained. Are output to the table 14 as conversion results.

When it is determined in step S12 that the above processing has been completed up to the last RGB data (Rx, Gx, Bx), the conversion means 13B terminates the processing. After that, the CMY data in the table 14 is
5 and color printing is performed.

[0032] On the other hand, the conversion table creation means 17A is activated from the input device 18, RGB as shown in FIG. 6
The required number of RGB data is generated by the data generation unit 171 and stored in the table 172 (S21). Here, in the present embodiment, a created flag EF is added to each RGB data and stored in the table 172, and all the created flags EF are initially set to OFF indicating that they are not created.

After that, the conversion table creation means 17A
It is determined whether or not a conversion request has been issued from the conversion unit 13B (S22).
3B), and the created flag EF of the RGB data stored in the table 172 is OFF.
Attention is paid to one of the RGB data (S23),
The RGB data is converted into CMY data by the conversion unit 173 (S25), color correction based on the masking coefficient is performed by the color correction unit 174 (S26), and K is generated and added by the K generation addition unit 175. (S2
7), the CMY data is set in the corresponding entry of the conversion table 16A and the valid flag VF is turned on (S
28), the created flag EF of the RGB data processed this time in the table 172 is set to ON (S29). Then, the process returns to step S22 to check again whether or not a conversion request has been issued from the conversion unit 13B. If not, the same processing as described above is executed for the next unconverted RGB data in the table 172. Then, when it is determined in step S24 that all the RGB data in the table 172 has been processed, the processing is terminated.

On the other hand, if the conversion table creation means 17A determines in step S22 that a conversion request has been issued from the conversion means 13B, the conversion table creation means 17A preferentially processes the RGB data requested to be converted. Execute That is, the RGB data requested to be converted is determined from the notified index I, the RGB data in the table 172 is noted (S30), and the RGB data is converted into CMY data by the conversion unit 173 (S3).
1) Next, color correction is performed by the color correction unit 174 (S3).
2) Next, K is created and added by the K creation adding unit 175 (S33), CMY data is set in the corresponding entry of the conversion table 16A, and the valid flag VF is set to O.
N (S34), and the RG processed this time in the table 172.
The created flag EF of the B data is set to ON (S3
5). Then, the conversion completion is notified to the conversion means 13B (S36), and the process returns to step S22 to continue the above operation.

The conversion table creation means in the embodiment of FIG. 4 17
A indicates the unprocessed R in the table 172 if the conversion request is not issued from the conversion unit 13B during the operation of the conversion unit 13B.
It was configured to process GB data. However, when the conversion unit 13B is activated, the processing of the unprocessed RGB data in the table 172 is interrupted, and the conversion unit 13B is given priority.
It may be configured to process the conversion request from B and restart the processing of the unprocessed RGB data in the table 172 when the operation of the conversion unit 13B stops.

Although the present invention has been described with reference to one embodiment, the present invention is not limited to the above embodiment, and various other modifications can be made. For example, the conversion table contains K
Is included, but the value of K may be separately created from the CMY data as the conversion result.

[0037]

According to the apparatus for converting RGB data into CMY data of the present invention as described above, the following effects can be obtained.

Even in the case where the RGB data has a format indicating the RGB intensity itself, CMY data that has been subjected to color correction can be obtained only by referring to the conversion table.
The conversion processing time can be greatly reduced.

A value (for example, a 24-bit value obtained by concatenating each of the 8 bits) obtained by combining the values of the three components of R, G, and B (for example, each value expressed by 8 bits) constituting the RGB data is represented by the CMY data. Since the conversion table is provided as an index, the corresponding CMY data can be searched at high speed.

[0040]

For the RGB data for which conversion was requested, C
A conversion table generating means for generating MY data and setting the conversion table in the conversion table; and a conversion target in the conversion table generating means when valid CMY data cannot be obtained from the conversion table when the RGB data to be converted is generated. R
Conversion means for notifying GB data, requesting conversion, and outputting the obtained CMY data as a conversion result .
Therefore , the conversion can be started even if the creation of the conversion table is not completed. In addition, since the CMY data of the RGB data that has appeared once is held in the conversion table, the conversion of the same RGB data from the second time can be performed at high speed with reference to the conversion table. Further, the conversion table creation means may output, during a period in which no conversion request is issued from the conversion means, or during a period in which the conversion means is not operating, among the predetermined RGB data patterns, Since the CMY data is generated and the process of setting the CMY data in the conversion table is performed, even if the conversion process is started without waiting for the completion of the creation of the conversion table, the conversion table can be completed quickly. The speed of the RGB data conversion process can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a base technology of the present invention.

FIG. 2 is a diagram illustrating a relationship between an RGB data pattern and an index I;

FIG. 3 is a flowchart illustrating a processing example of a conversion unit 13;

FIG. 4 is a configuration diagram of one embodiment of the present invention.

FIG. 5 is a flowchart illustrating a processing example of a conversion unit 13B.

FIG. 6 is a flowchart illustrating a processing example of a conversion table creating unit 17A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Center 11 ... Receiving part 12 ... Table holding RGB data to be converted 13 ... Conversion means 14 ... Table holding CMY data after conversion 15 ... Printing means 16 ... Conversion table 17 ... Conversion table creation means 171 RGB data generation unit 172 table 173 conversion unit 174 color correction unit 175 K creation addition unit 18 input device 2 terminal 21 scanner 22 transmission unit 3 communication line 4 medium for recording color images

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46-1/64

Claims (2)

(57) [Claims] 1. RGB of all predetermined patterns
A conversion table for storing CMY data that has been subjected to color correction based on a masking coefficient set according to the printing environment for data, and a masking set according to the printing environment for RGB data requested to be converted A conversion table generating means for generating CMY data subjected to color correction based on the coefficients and setting the CMY data in the conversion table; and when generating RGB data to be converted, the CMY data corresponding to the RGB data is stored in the conversion table. Searching, when valid CMY data is obtained, outputs the CMY data as a conversion result. When valid CMY data is not obtained, the conversion table creating means is notified of the RGB data to be converted, and A conversion means for requesting conversion and outputting the obtained CMY data as a conversion result; Conversion table creating means, all predetermined R
A process of generating CMY data that has been subjected to color correction based on a masking coefficient set according to a printing environment for RGB data that has not yet been subjected to a conversion process among the patterns of the GB data, and setting the same in the conversion table, An apparatus for converting RGB data into CMY data, wherein the conversion is performed during operation of the conversion unit or during non-operation of the conversion unit. 2. The conversion table according to claim 1, wherein a value obtained by combining values of three components of R, G, and B constituting RGB data is used as an index of CMY data, and holds a valid bit indicating the validity of the CMY data. 2. The apparatus for converting RGB data into CMY data according to claim 1, wherein: