JP3034278B2 - Image recording apparatus and color image processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image processing apparatus and a color image processing method for inputting and processing color data.

2. Description of the Related Art Conventionally, a printing apparatus of this type always outputs R (red), G (green), and B (blue) data each time it inputs Y (yellow), M (color) data by a color processing routine.
(Magenta), C (cyan) or Y, M, C, K (black) has been processed.

[Problems to be Solved by the Invention] However, if the accuracy of RGB to YMC or YMCK conversion is increased to improve color reproducibility, the conversion formula becomes complicated, and the digit accuracy of intermediate data is reduced. There is a drawback that the conversion speed decreases because it is necessary to increase the conversion speed. In particular, each RGB data is data for one pixel, and it is all the more necessary to perform an enormous number of calculations to obtain an entire image.

The simplest method is to prepare the correspondence between the input color components and the output color components in advance as a look-up table, and utilize this.

However, in order to enhance color reproducibility, the number of bits of each color component must be secured to some extent.
The memory capacity of the conversion table is enormous.

The present invention has been made in view of such a problem,
An object of the present invention is to provide a color image processing method for generating output color component data at high speed without requiring the capacity of a conversion table for an actual color space, and an image recording apparatus for actually recording a color image.

[Means for Solving the Problems] To solve the problems, for example, an image recording apparatus of the present invention has the following configuration. That is, in an image recording apparatus that converts data in an input color component format into data in a recording color component format and records an image, a second device that converts data in the input color component format into data in a recording color component format by calculation. 1 conversion means, and a conversion table in which data of the input color component format and data of the recording color component format corresponding to the data of the input color component format are recorded in association with each other. Second converting means for converting the data of the color component format into data of the recording color component format; determining means for determining whether or not the input color component format data is stored in the conversion table; When it is determined that the data is not stored, the corresponding conversion color component format data is obtained by using the second conversion unit, and when it is determined that the data is not stored by the determination unit. The first conversion means converts the data in the corresponding color component format into the corresponding color component format data, and records the input color component format data and the data obtained by the conversion in the conversion table in association with each other. And control means for constructing the conversion table.

The color image processing method of the present invention includes the following steps. That is, a color image processing method for converting input color data into output color data and outputting the output color data, comprising: a first conversion step of converting input color data into output color data by operation; A second conversion step of converting input color data into output color data using a conversion table in which output color data corresponding to the input color data are recorded in association with the input color data. A discriminating step of discriminating whether or not the output color data is stored in the discriminating step, corresponding output color data is generated in accordance with the second conversion step, and is not stored in the discriminating step. Is determined, the corresponding output color data is generated by the first conversion step, The input color data and associates the generated output color data has been stored in the conversion table, and a control step of constructing the conversion table.

Embodiment An embodiment according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a printing apparatus according to an embodiment.
The printing devices of the embodiments are Y (yellow), M (magenta),
This device records a color image using four color components of C (cyan) and K (black).

In the drawing, the printing apparatus main body 1 indicated by a solid line includes:
An external host computer 2 is connected via a connector (not shown), and is configured to receive a command or the like from the host computer 2 and print out.

Various components shown below are connected to the CPU 3 that performs all controls in the main body 1. Reference numeral 4 denotes a reception buffer for temporarily storing reception data such as commands from the host computer 2; and 5, a ROM in which a program for executing a series of control flows and the like are stored, including a flowchart shown in FIG. , 6 is RAM used as a work area when CPU3 executes a program, and 7 is YMCK
Is an output unit that outputs each image data. A power supply device (not shown) is also connected.

The RAM 6 stores an RGB-YMCK conversion data.
The GB / YMCK conversion table 6a is secured, and the contents are as shown in FIG.

As shown in the figure, the RGB-YMCK conversion table 6a of the embodiment stores the R, G, B data at the time of conversion from RGB to YMCK and the Y, M, C, K data converted thereby. As a set, a total of N sets of converted data can be stored (“N” is RA
Value that depends on the memory capacity of M6). When the power is turned on, no data is stored in the conversion table 6a, and the conversion table is constructed while the printing process is repeated.

At the time of actual printing, based on the values of Y, M, C, and K obtained by analyzing a command related to a color designation command received from the host computer 2, a character pattern corresponding to an image or a character code input thereafter. Is printed.

The current print colors (Y, M, C, and K values) are stored in a current variable secured at a predetermined address position in the RAM 6, and a procedure for determining the value of the current variable is described in the flowchart of FIG. This will be described with reference to FIG.

The output unit 7 in the embodiment may be a laser beam printer, an ink jet printer, or a thermal transfer printer. It is also assumed that variables “n” and “i” used in the following description are also reserved at predetermined address positions in the RAM 6.

When power is supplied to the main body 1, the CPU 3 firstly executes a step.
In S1, a variable n of the number of valid tables on the RAM 6 is initialized to "0". This effective table number variable n is currently RGB-YMC
It serves as a pointer indicating how far the conversion data is stored in the K conversion table 6a. That is, in the step S1, the fact that no conversion data is stored in the RGB-YMCK conversion table 6a of the RAM 6 is set.

Before and after the description, an interrupt signal is generated in the CPU 3 when data is received from the host computer. The CPU 3 performs processing for sequentially storing the data received by this interrupt routine in the reception buffer 4.

Next, in step S2, one unit of data is read from the reception buffer 4, and it is determined whether the data is data corresponding to a color designation command, print command data, or paper ejection command data.

If the instruction is a color designation instruction, the process proceeds to step S4, where a variable i used as a pointer of the table reference position is set to "0".
To Then, proceeding to the next step S5, the variable i is compared with the variable n, and it is determined whether or not "i <n" is satisfied.

Although the details will be clear from the following description, the fact that this inequality is not satisfied indicates that the same command as the color designation command command that has just been input has not been input in the past. In other words, it is determined that the RGB value corresponding to the RGB-YMCK conversion table 6a does not exist. Therefore, if this inequality is not satisfied, the process proceeds to step S9.

In step S9, R, G,
B data is actually converted into Y, M, C, K data.

FIG. 4 briefly shows the RGB-YMCK conversion algorithm.

In step S17, by density conversion (log conversion), first, R,
Convert G, B data to C, M, Y data. Next, step S1
In step 8, C, M, and Y are converted to C, M, Y, and K data by under color removal (UCR) processing. Next, in step S19, C, M, and Y are masked to correct C, M, and Y. Finally, step S20
Then, each data of C, M, Y, K is corrected by γ conversion to obtain Y, M, C, K data for actual printing.

Returning to FIG. In step S10, the Y, M, C, K data obtained as described above is set in the current YMCK variable on the RAM. Next, in step S11, it is determined whether or not the variable n is smaller than the maximum size N of the maximum RGB-YMCK conversion table 6a (this value is stored in advance in a ROM or the like). If n <N, there is still room for data storage in the RGB-YMCK conversion table 6a.
The RGB value and the converted YMCK value are set in the second table, and the number n of valid tables is incremented by one in step S13, and the result is determined in step S2.
Return to

If it is determined in step S11 that the variable n is not smaller than the maximum size N of the maximum RGB-YMCK conversion table 6a, in other words, if it is determined that there is no empty area in the RGB-YMCK conversion table 6a, the process proceeds. Goes to step S14, and R
The new RGB data and YMCK data are overwritten on the head table "0" of the GB-YMCK conversion table 6a, and the process returns to step S2.

Thus, different types of RGB are stored in the RGB-YMCK conversion table 6a as long as the preset maximum size N permits.
A conversion table based on the data and the YMCK data converted based on the data is constructed.

If it is determined in step S5 that "i <n" is satisfied, the process proceeds to step S6. In step S6, the i-th table is referred to from the RGB-YMCK conversion table 6a, and it is determined whether or not the value of the reference RGB is equal to the RGB data according to the input color designation command. For example, reference RGB
Is R ', G', B 'and the data of each color component by the command of the input color designation command is R, G, B,
When R '= R, G' = G, B '= B, it is determined that they are equal. When any one of them is not satisfied, it is determined that they are not equal.

If it is determined that they are not equal to each other, it is necessary to refer to the next table, so the variable i is incremented by "1", and the process returns to step S5. Thus, when it is determined that equal data exists in the RGB-YMCK conversion table 6a in the process of referring to the tables one after another, that is, the conversion value to the YMCK data for the input color specification instruction is already RGB.
When it is determined that the i-th data exists in the -YMCK conversion table, the process proceeds to step S7. In step S7, the YMCK value of the i-th table of the variable at that time is obtained, processing for setting this value to the current YMCK variable in the RAM 6 is performed, and the process returns to step S2.

In the loop of steps S5, S6, and S8, if it is determined that a matching table cannot be found even at the end, the process proceeds to step S9, where processing for converting the YMCK data is performed, and RGB-YMCK is performed. Additional storage is performed as long as the capacity of the conversion table 6a (depending on the N value) permits.

If it is determined in step S3 that the command is a print command, the flow advances to step S15 to change the character pattern to be printed according to the value (print color) indicated by the current YMCK variable in RAM6.
Draw on the YMCK bitmap and return to step S2.

If it is determined in step S3 that the command is a sheet ejection command, step S1 is executed.
The program proceeds to step S6, where the YMCK bit map on the RAM 6 is output to the output unit 7 to output the paper, and the process returns to step S2.

As described above, according to the present embodiment, the designated RG
The B data and the converted YMC or YMCK data are stored. If the input RGB data is determined to be equal to the stored RGB data by a certain comparison function, the stored YMC or YMCK is used. Accordingly, when the same RGB data is repeatedly input, the processing required for converting from RGB to YMC or YMCK is not required, so that the speed can be improved.

Note that the RGB-YMCK table 6a in the RAM 6 in the embodiment is constructed in the order of the input RGB designation data, but is sorted in ascending order (or descending order) at appropriate timing.
The processing related to the search may be performed at high speed (∵The approximate position can be determined by sorting).

When the table is full, the data to be overwritten may be the oldest data registered in the table or the oldest data referred to.

In step S6 in FIG. 3 of the embodiment, as means for judging whether or not they are equal, the input color designation command
When the R, G, B data and the reference R, G, B in the conversion table 6a completely match, it is determined that they are equal, but they may have a certain width.

For example, the data according to the input color designation command is R, G, B, and the reference data R ′, G ′,
When B ′, R′−ε _r ≦ R ≦ R ′ + ε _r G′−ε _g ≦ G ≦ G ′ + ε _g B′−ε _b ≦ B ≦ B ′ + ε _b is determined to be equal. If one is not satisfied, it may be determined that they are not equal.

Further, the RGB-YMCK conversion may be performed for each pixel of the RGB image data without depending on the color designation command command as in the present embodiment. It goes without saying that a YMC printer may be used instead of the YMCK printer.

In the present embodiment, the input color component data is R, G,
Although B is used, a configuration may be used in which Y, M, C, and K data is obtained by inputting, for example, Y, I, and Q data, L ^* , a ^* , and b ^* data.

[Effects of the Invention] As described above, according to the present invention, by using both an operation and a conversion table to generate an output color component, an entire image is obtained without using a conversion table in a real color space. The number of operations up to can be reduced. Therefore, the conversion process can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram of the printing apparatus of this embodiment, FIG. 2 is a schematic diagram of an RGB-YMCK conversion table of this embodiment, FIG. 3 is a flowchart relating to color designation of this embodiment, and FIG. FIG. 8 is a diagram showing an algorithm of an RGB-YMCK conversion routine. In the figure, 1 ... printing apparatus main body, 2 ... host computer, 3 ... CPU, 4 ... reception buffer, 5 ... ROM, 6 ...
... RAM, 6a ... RGB-YMCK conversion table, 7 ... output unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/525 B41J 5/30 H04N 1/46 H04N 1/60

Claims (7)

(57) [Claims] An image recording apparatus for converting an input color component format data into a recording color component format data and recording an image, wherein the input color component format data is converted into a recording color component format data by calculation. A first conversion means for converting, and a conversion table in which input color component format data and recording color component format data corresponding to the input color component format data are recorded in association with each other, Second conversion means for converting data of the color component format into data of the recording color component format; determination means for determining whether or not the input data of the color component format is stored in the conversion table; If it is determined that the data is stored, the corresponding color component format data is obtained using the second conversion means. And converting the input color component format data and the converted data into the corresponding color component format data by the first conversion means, and recording the converted color component format data in the conversion table. And a control unit for constructing the conversion table. 2. A color image processing method for converting input color data into output color data and outputting the output color data, comprising: a first conversion step of converting input color data into output color data by operation; A second conversion step of converting input color data into output color data using a conversion table in which output color data corresponding to input color data is recorded in association with the input color data; A discriminating step of discriminating whether or not the image data is stored in the memory. If it is determined that the data is stored in the discriminating step, corresponding output color data is generated in accordance with the second conversion step. If it is determined that the output color data is not stored, corresponding output color data is generated by the first conversion step. Both the color image processing method characterized by comprising a control step of associating the output color data generated with the input color data stored in the conversion table, constructing the conversion table. 3. The conversion table can store N sets of sets of input color data and output color data.
3. The method according to claim 2, wherein the output color data obtained in the first color conversion step is overwritten and stored when N pieces of data have already been stored. The color image processing method according to the above item. 4. The color image processing method according to claim 3, wherein the object to be overwritten is the oldest stored data in the conversion table. 5. The color image processing method according to claim 3, wherein the object to be overwritten is data that is referred to the oldest in the conversion table. 6. The color image processing method according to claim 2, further comprising the step of sorting the contents of said conversion table. 7. The determining step includes providing a predetermined allowable range for the input color data, and determining whether there is data within the allowable range stored in the conversion table. 3. The color image processing method according to claim 2, wherein: