Color image signal processing device

• US 5,631,749 A
• Filed: 12/15/1995
• Issued: 05/20/1997
• Est. Priority Date: 01/12/1995
• Status: Expired due to Term

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Ueda, Masashi
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): NGUYEN, ANH-VINH THI
• Application Number:
  US08/573,488
• Time in Patent Office: 522 Days
• Field of Search: 358/518, 358/520, 358/521, 358/515, 358/524, 358/525, 358/523, 358/530, 358/500, 358/501, 382/274
• US Class Current: 358/520
• CPC Class Codes: H04N 1/6075 Corrections to the hue
• CPC Class Codes: H04N 1/622 with simulation on a subsidiary picture reproducer
• CPC Class Codes: H04N 1/628 Memory colours, e.g. skin or sky

Abstract

Any color on a CRT display is selected, and a selection operation is carried out to adjust the selected color to a color which is suitable to be reproduced by a printer. On the selected information, a hue conversion table adjustment unit corrects a conversion characteristic data of a hue conversion table. A hue component of a color signal on the CRT display is converted using the corrected conversion characteristic data.

Claims

1. A color image signal processing device, comprising:

hue calculation means for calculating a hue value from the color signal of an image for a first device;

hue conversion means for converting the hue value calculated in said hue calculation means to reproduce the image by a second device;

first color selection means for selecting a color of an image for said first device;

second color selection means for selecting a color to be reproduced by said second device; and

conversion characteristic correcting means for correcting a conversion characteristic of said hue conversion means on the basis of the color selected by said first color selection means and the color selected by said second color selection means.

2. The color image signal processing device as claimed in claim 1, wherein said hue conversion means includes hue conversion value storage means for presetting and storing hue values of said first device into which a hue range of said first device is arbitrarily divided and hue values of said second device which correspond to the hue values of said first device, said conversion characteristic correcting means including address calculation means for calculating an address in said hue conversion value storage means on the basis of the color selected by said first color selection means, hue conversion characteristic calculation means for calculating a new conversion characteristic on the basis of the colors which are selected by said first color selection means and said second color selection means, and hue conversion value correcting means for correcting a storage content of said hue conversion value storage means on the basis of the address calculated by said address calculation means and the new conversion characteristic calculated by said hue characteristic calculation means.

3. The color image signal processing device as claimed in claim 1, wherein the second color selection means is a color adjustment amount inputting means.

4. The color image signal processing device as claimed in claim 3, wherein the color adjustment amount inputting means inputs a hue adjustment amount Δ

H.

5. A color image signal processing device, comprising:

a first output device for a color image;

a second output device for a color image;

a first controller for controlling the first output device;

a second controller for controlling the second output device;

input means connected to the first controller;

a read only memory electronically connected to the second controller storing hue conversion data; and

a random access memory electronically connected to the second controller containing a working area and space for a hue conversion table, wherein the second controller includes means for calculating hue, a hue conversion table adjustment unit and a color converter, the first and second controllers electrically connected to permit selection of a hue for correction and the amount of correction to be applied.

6. The color image signal processing device as claimed in claim 5, wherein the first output device is a CRT display and the second output device is a color printer.

7. The color image signal processing device as claimed in claim 6, wherein the means for calculating hue calculates a hue for the second output device based on the amount of correction to be applied to the selected hue from the first output device.

8. The color image signal processing device as claimed in claim 7, wherein the means for calculating hue is a hue adjuster which is a part of the second controller.

9. The color image signal processing device as claimed in claim 6, wherein the hue conversion table adjustment unit changes the hue conversion table to reflect an output hue for the second output device based upon the selected hue of the first output device.

10. A method for converting a hue shown on a first output device to a hue output to a second output device, comprising the steps of:

selecting a color from the first output device, as an XYZ_in value;

calculating a L*a*b*_in value from the XYZ_in value;

converting the L*a*b*_in value to an input hue value H_in ;

determining whether a value H_OUT exists in a hue conversion means that corresponds to H_in ;

establishing a value H_OUT ;

calculating an L*a*b*_out value based on H_OUT ;

converting the L*a*b*_out value to a XYZ_out value;

converting the XYZ_out value to a CMY signal; and

outputting the CMY signal to the second output device.

11. The method as claimed in claim 10, wherein the step of establishing a value H_OUT further comprises the step of checking a lookup table to determine whether a value H_OUT exists for the value H_in.

12. The method as claimed in claim 11, wherein when a value H_OUT does not exist in the table for the value H_in, the step of establishing a value H_OUT further comprises the steps of using table values to interpolatively calculate the value H_OUT.

13. The method as claimed in claim 12, wherein interpolatively calculating the value H_OUT determines the relationship of H_in to table values on either side of H_in and calculates the value H_OUT to have a similar relationship to table values H_OUT corresponding to the table values on either side of H_in.

14. The method as claimed in claim 13, further comprising the step of adjusting the table to incorporate the value H_in and the interpolated value H_OUT corresponding thereto.

15. The method as claimed in claim 10, wherein calculating the L*a*b*_in value is calculated according to:

space="preserve" listing-type="equation">L*=116(Y/Yn).sup.1/3 -16

space="preserve" listing-type="equation">a*=500{(X/Xn).sup.1/3 -(Y/Yn).sup.1/3 }

space="preserve" listing-type="equation">b*=200{(Y/Yn).sup.1/3 -(Z/Zn).sup.1/3 }

where a white color on the first output device is represented by X_n, Y_n and Z_n.

16. The method as claimed in claim 15, wherein when any one of X/X_n, Y/Y_n, and Z/Z_n is less than 0.00856, the corresponding cubic root is substituted by 7.787(X/X_n)+16/116, 7.787(Y/Y_n)+16/116, and 7.787(Z/Z_n)+16/116.

17. The method as claimed in claim 10, wherein the L*a*b*_in value is converted to the hue value H_in by:

space="preserve" listing-type="equation">HO=ARCTAN(b*/a*)·

180/π

;

where

space="preserve" listing-type="equation">for a*>

0 and b*≧

0, H.sub.in =HO

space="preserve" listing-type="equation">for a*<

0 and b*≧

0, H.sub.in =180-HO

space="preserve" listing-type="equation">for a*>

0 and b*≦

0, H.sub.in =HO+180

space="preserve" listing-type="equation">for a*<

0 and b*≦

0, H.sub.in =360-180

space="preserve" listing-type="equation">for a*=0 and b*>

0, H.sub.in =90

space="preserve" listing-type="equation">for a*=0 and b*<

0, H.sub.in =270

for a*=0 and b*=0, there is only brightness, no color, therefore H=0.

18. The method as claimed in claim 10, where the step of calculating the L*a*b*_out value uses:

space="preserve" listing-type="equation">L*.sub.out =L*.sub.in

space="preserve" listing-type="equation">a*.sub.out =Cos(H.sub.OUT ·

π

/180)×

(a.sub.in.sup.*2 +b.sub.in.sup.*2).sup.1/2

space="preserve" listing-type="equation">b*.sub.out =Sin(H.sub.OUT ·

π

/180)×

(a.sub.in.sup.*2 +b.sub.in.sup.*2).sup.1/2.

19.

19. The method as claimed in claim 10, wherein the step of converting the L*a*b_out value to the XYZ_out value is done by:

space="preserve" listing-type="equation">YO=(L*.sub.out +16)/116

space="preserve" listing-type="equation">XO=a*.sub.out /500+YO

space="preserve" listing-type="equation">ZO=YO-b*.sub.out /200

space="preserve" listing-type="equation">X.sub.out =XO.sup.3 +Xn

space="preserve" listing-type="equation">Y.sub.out =YO.sup.3 +Yn

space="preserve" listing-type="equation">Z.sub.out =ZO.sup.3 +Zn.

20. The method as claimed in claim 19, wherein when any one of XO, YO and ZO is less than 0.008856^1/3, the corresponding X_out, Y_out and Z_out values are calculated using:

space="preserve" listing-type="equation">X.sub.out =(XO-16/116)/7.787

space="preserve" listing-type="equation">Y.sub.out =(YO-16/116)/7.787

space="preserve" listing-type="equation">Z.sub.out =(ZO-16/116)7.787.