JP2004306465A - Method of correcting color in printer, incidental information extracting device, and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for mounting a common LUT on various models, facilitating representation of a quantity of a black designated by a user, and carrying out correction of a color by a pixel unit. <P>SOLUTION: A page printer 20 consists of an incidental information extracting section 20A and an RGB printer section 20B. In the incidental information extracting section 20A, a quantity Q<SB>i</SB>of ink to be used and object information o<SB>i</SB>is extracted by a PDL analyzing section 21 and the quantity Q<SB>i</SB>is converted to RGB data J<SB>i</SB>by using an LUT group 23 by an LUT selecting section 22. The LUT selecting section 22 obtains a correction quantity k<SB>i</SB>of a black color K in inks. In the RGB printer section 20B, the RGB data J<SB>i</SB>is converted to the quantity Q<SB>i</SB>'' of ink to be used based on the object information o<SB>i</SB>by using an LUT group 25 by an LUT selecting section 24. The quantity Q<SB>i</SB>'' is corrected by the correction quantity k<SB>i</SB>to obtain a quantity Q<SB>i</SB>' of ink to be used by a color correcting section 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for controlling the operation of a printer, and more particularly, to a printer that operates based on a page description language.
[0002]
[Prior art]
FIG. 2 is a block diagram illustrating the structure of the conventional page printer 10. The page description language (PDL) input from the outside is analyzed by the PDL analysis unit 11, and the ink usage amount Q _i = (C _i , M _i , Y _i , K _i ) and the accompanying information P _i for a certain pixel i are used. Is required. The accompanying information P _i includes, for example, the type A _{i of the} press simulation and the screen information α _i indicating the type of the screening for the pixel i.
[0003]
The amount _{Q i} is necessarily not immediately be used as the ink discharge amount, the amount of ink based on a predetermined look-up table _{(LUT) Q i '= (} C i', M i ', Y i' , K _i ′). The LUT used for the conversion is selected from the LUT group 13 depending on the type A of the press simulation and the type α of the screening. The selection of the LUT and the conversion of the amount of ink used are performed by the LUT selection unit 12.
[0004]
The used amount Q _i ′ of the converted ink is transmitted to the ink ejection unit 14 and used as the used amounts C _i ′, M _i ′, Y _i ′, and K as the ejection amounts of the cyan, magenta, yellow, and black inks, respectively. _i ′ is adopted.
[0005]
In addition, a technique for converting the used amount of each of a plurality of inks into a new used amount for each of the inks using a predetermined LUT is introduced in, for example, Patent Document 1.
[0006]
[Patent Document 1]
US Pat. No. 4,500,919.
[Problems to be solved by the invention]
However, although the page printer 10 generally has an LUT for converting color data from the RGB color space to the CMYK color space, it does not use it. Also, when changing the color tone of the page printer 10, the LUT group 13 needs to be recreated. Also, of course, the LUT group 13 must be created for each model of the page printer 10. Also, color correction could not be performed in pixel units.
[0008]
The present invention has been made in view of the above circumstances, and is capable of mounting a common LUT regardless of the model, facilitating reproduction of a black amount specified by a user, and further performing color correction in pixel units. It is intended to provide.
[0009]
[Means for Solving the Problems]
In the color correction method for a printer according to the present invention, (a) extracting, from a page description language (PDL), a first usage amount (Q _i ) of ink provided in the printer and object information (ο _i ) indicating a type of an object. , (B) a correction amount (κ _i ) for the specific color (K) in the ink is obtained based on the first usage amount and the object information, and (c) the first usage amount is converted into RGB data. Then, (d) the RGB data is converted into a second usage amount (Q _i ″) of the ink based on the object information (ο _i ), and (e) the second usage amount is corrected by the correction amount, and the second usage amount of the ink is corrected. 3. Calculate the usage (Q _i ′).
[0010]
Since the RGB data and the object information are once obtained in steps (a) to (c), a common LUT is adopted regardless of the model in order to obtain the second amount of ink used in step (d). be able to. In addition, color correction can be performed in step (e) with the correction amount obtained in step (b).
[0011]
In step (a), the user-specified rendering intent (λ _i ) is also extracted from the page description language. In step (b), the correction amount is determined based on the first usage amount and the object information and the user-specified rendering intent. If so, color correction can be performed based on a rendering intent suitable for the object.
[0012]
In step (b), a rendering intent (θ _i ) for each object is also obtained based on the object information and the rendering intent specified by the user. In step (d), the rendering intent (θ _i ) for each object is calculated. If the RGB data is converted into the second usage based on the above, a second usage suitable for the rendering intent of a certain object can be obtained.
[0013]
In step (a), screen information (α _i ) is also extracted from the page description language, and in step (d), if the RGB data is converted to the second usage based on the screen information, A suitable second usage can be obtained.
[0014]
In step (a), the type of press simulation (A _i ) is also extracted. In step (b), the first usage amount is converted into RGB data based on the type of press simulation. RGB data can be obtained.
[0015]
In particular, if steps (a) to (e) are performed for each pixel, color correction can be performed for each pixel. Further, in step (a), a pixel position (χ _i ) indicating the position of the pixel is also extracted from the page description language, and in step (e), the second usage amount is corrected by the pixel position and the correction amount, and the third usage amount is corrected. If the amount is obtained, color correction is performed based on the pixel position, so that the color difference on the same printing surface can be reduced.
[0016]
The accompanying information extraction device according to the present invention includes a PDL analysis unit (21) and conversion units (22, 23). The PDL analysis unit executes step (a) of the printer color correction method according to the present invention, and the conversion unit executes steps (b) and (c) of the printer color correction method according to the present invention.
[0017]
A printer according to the present invention includes an ink ejection unit (27) having a plurality of color inks, a conversion unit (24, 25), and a color correction unit (26). Then, the conversion unit executes step (d) of the color correction method of the printer according to the present invention, and the color correction unit executes step (e) of the color correction method of the printer according to the present invention.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram showing the structure of a printer, for example, a page printer 20, according to an embodiment of the present invention. The page printer 20 can be divided into an accompanying information extraction unit 20A and an RGB printer unit 20B.
[0019]
The accompanying information extraction unit 20A includes a PDL analysis unit 21, an LUT selection unit 22, and an LUT group 23. The accompanying information extraction unit 20A inputs a page description language (PDL) from outside the page printer 20, analyzes the contents, and uses the ink usage amount Q _i = (C _i , M _i , Y for the pixel i). _i , K _i ) and accompanying information P _i are extracted. In the accompanying information P _i , the type A _i of the press simulation, the screen information α _i , the rendering intent λ _i designated by the user, the object information o _i indicating the type of the object, and the pixel indicating the position of the pixel i for the pixel i Position χ _i is included.
[0020]
The screen information can be exemplified by two types of gradation priority / resolution priority, and the rendering intent can be exemplified by four types of perception / saturation / relative color retention / absolute color retention. As the types of objects, three types of images / texts / illustrations can be exemplified.
[0021]
The LUT selection unit 22 performs data conversion based on the LUT for converting the ink usage amount CMYK into RGB (red; green; blue) data for each type A of the press simulation. For example, the ink usage Q _i = (C _i , M _i , Y _i , K _i ) is changed to RGB data J _i = (R _i , G _i , B _i ) by the LUT corresponding to the type A _{i of the} press simulation. Is converted. Thus, RGB data suitable for the type of press simulation can be obtained.
[0022]
The LUT selection unit 22 further outputs data to which the additional information P _i ′ and the correction information P _i ″ are added. The additional information P _i ′ includes the screen information α _i , the object information o _i , and the rendering intent for the pixel i. including theta _i. the correction information _{P i} "comprises pixel position chi _i and black correction amount kappa _i. Note that four types of black correction amount, strong / normal / weak / none, can be exemplified.
[0023]
The rendering intent θ _i is determined as a rendering intent suitable for the type of the object based on the rendering intent λ _i specified by the user and the object information o _i, so that this determination can be made based on the LUT. Further, since the black correction amount κ _i is determined by the rendering intent λ _i specified by the user, the object information o _i , and the ink usage amount CMYK, this determination can be made based on the LUT. As described above, the LUT for obtaining the accompanying information data P _i ′ and the correction information P _i ″ are combined into an LUT for obtaining RGB data, and are denoted as “CMYKtoRGB ⁺ LUT” in FIG. These LUTs constitute the LUT group 23.
[0024]
The RGB printer unit 20B includes an LUT selection unit 24 and an LUT group 25. The RGB data J _i and the accompanying information P _i ′ are input to the LUT selection unit 24, and an LUT is selected from the LUT group 25 based on the accompanying information P _i ′. The LUT converts the RGB data into the amount of ink used CMYK. The LUT corresponding to the screen information α _i , the object information o _i , and the rendering intent θ _i is selected. Therefore, the amount of ink Q appropriate for the type of screening and the rendering intent suitable for the type of object is selected. _i ″ = (C _i ″, M _i ″, Y _i ″, K _i ″).
[0025]
The RGB printer unit 20B includes a color correction unit 26, and inputs the ink usage amount Q _i ″ and correction information P _i ″. Then, the ink usage amount Q _i ″ is corrected using the correction information P _i ″, and the ink usage amount Q _i ′ = (C _i ′, M _i ′, Y _i ′, K _i ′) as the actual ejection amount. ) Is required.
[0026]
The RGB printer unit 20B further includes an ink ejection unit 27, and ejects cyan, magenta, yellow, and black inks based on the used amount Q _i ′ of ink.
[0027]
Since the color correction unit 26 can perform color correction for each pixel i, it is easy to reproduce the black amount specified by the user. It may further perform color correction in pixels, since the color correction also based on the pixel position chi _i, it is possible to reduce the color difference in the same printing surface.
[0028]
In addition, since the LUT group 25 prepares an LUT for each piece of accompanying information P _i ′, it is not necessary to prepare a different LUT for each model when obtaining the ink usage amount Q _i ″.
[0029]
Of course, RGB printer unit 20B, if the input RGB data _{J i} and black correction amount kappa _i externally, as printers only this, it is possible to function as a so-called RGB printer. In other words, as an RGB printer, color correction can be performed for each pixel as in the color correction unit 26, and if an LUT is prepared for each piece of accompanying information P _i ′ as in the LUT group 25, the RGB printer is On the other hand, only by adding an incidental information extraction device corresponding to the incidental information extraction unit 20A, it is possible to function as the page printer 20 capable of inputting a page description language including information on ink usage.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a structure of a page printer according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating the structure of a conventional page printer.
[Explanation of symbols]
21 PDL analysis unit 22, 24 LUT selection unit 23, 25 LUT group 26 Color correction unit A _i Press simulation type Q _i , Q _i ′, Q _i ″ Ink usage J _i RGB data P _i ′ Associated information P _i ”Correction information α _i screen information θ _i rendering intent κ _i black correction amount λ _i user specified rendering intent ο _i object information ο _i pixel position

Claims (19)

(A) extracting, from a page description language (PDL), a first usage amount (Q _i ) of ink provided in the printer and object information (ο _i ) indicating an object type;
(B) obtaining a correction amount (κ _i ) for a specific color (K) in the ink based on the first usage amount and the object information; (22, 23);
(C) converting the first usage amount into RGB data (22, 23);
(D) converting the RGB data into a second usage amount (Q _i ″) of the ink based on the object information (ο _i );
(E) correcting the second usage amount with the correction amount to obtain a third usage amount (Q _i ′) of the ink (26). In the step (a), a user-specified rendering intent (λ _i ) is also extracted from the page description language,
The color correction method for a printer according to claim 1, wherein in the step (b), the correction amount is obtained based on the first usage amount, the object information, and the rendering intent specified by the user. In the step (b), a rendering intent (θ _i ) for each object is also obtained based on the object information and the rendering intent specified by the user,
3. The color correction method for a printer according to claim 2, wherein in the step (d), the RGB data is converted into the second usage based on a rendering intent (θ _i ) for each object. In the step (a), screen information (α _i ) indicating the type of screening is also extracted from the page description language,
4. The color correction method for a printer according to claim 1, wherein in the step (d), the RGB data is converted into the second usage based on the screen information. 5. In the step (a), the type (A _i ) of the press simulation is also extracted,
The method according to any one of claims 1 to 4, wherein in the step (b), the first ink usage is converted into RGB data based on the type of the press simulation. 6. The method according to claim 1, wherein steps (a) to (e) are performed for each pixel. In the step (a), a pixel position (χ _i ) indicating a pixel position is also extracted from the page description language,
7. The color correction method for a printer according to claim 6, wherein in the step (e), the second usage amount is corrected by the pixel position and the correction amount to obtain the third usage amount. A PDL analysis unit (21) for extracting, from a page description language (PDL), an amount of ink used (Q _i ) provided in the printer and object information (ο _i ) indicating the type of the object;
A conversion unit for determining a correction amount (κ _i ) for a specific color (K) in the ink based on the usage amount and the object information and converting the usage amount into RGB data; An accompanying information extracting device (20A) provided. The PDL analysis unit also extracts a user-specified rendering intent (λ _i ) from the page description language,
The apparatus according to claim 8, wherein the conversion unit obtains the correction amount based on the first usage amount, the object information, and the rendering intent specified by the user. The converting unit, based on said object information and said user-specified rendering intent, determining rendering intent (theta _i) also of each object, accompanying information extraction apparatus according to claim 9, wherein. The accompanying information extraction device according to any one of claims 8 to 10, wherein the PDL analysis unit also extracts screen information (α _i ) indicating a type of screening from the page description language. The PDL analysis unit also extracts the type of press simulation (A _i ),
The incidental information extraction device according to claim 8, wherein the conversion unit converts the first ink usage amount into RGB data based on a type of the press simulation. 13. The accompanying information extraction device according to claim 8, wherein the extraction in the PDL analysis unit and the conversion in the conversion unit are performed for each pixel. 14. The accompanying information extraction device according to claim 13, wherein the PDL analysis unit also extracts a pixel position (χ _i ) indicating a pixel position from the page description language. An ink ejection unit (27) including a plurality of color inks,
A conversion unit (24, 25) that converts the RGB data into a first usage amount (Q _i ″) of the ink based on object information (ο _i ) indicating the type of the object;
A color correction unit that corrects the first usage amount with a correction amount (κ _i ) for a specific color (K) in the ink to obtain a second usage amount (Q _i ′) of the ink; (20B) comprising: Wherein the conversion unit is also based on the rendering intent for each of the objects (theta _i), converts the RGB data to the first usage claim 15 printer according. 17. The printer according to claim 15, wherein the conversion unit converts the RGB data into the first usage based on screen information indicating a type of screening. 18. The printer according to claim 15, wherein the conversion in the conversion unit and the correction in the color correction unit are executed for each pixel. 19. The printer according to claim 18, wherein the conversion unit obtains the second usage amount by correcting the first usage amount with a pixel position (χ _i ) indicating a pixel position and the correction amount.

Images