Method and apparatus for adjusting correlated color temperature

• US 5,532,848 A
• Filed: 11/25/1992
• Issued: 07/02/1996
• Est. Priority Date: 11/25/1992
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Information Systems Incorporated (Canon Inc.)
• Inventors: Beretta, Giordano B.
• Primary Examiner(s): Rogers, Scott A.
• Application Number:
  US07/981,437
• Time in Patent Office: 1,315 Days
• Field of Search: 358/29, 358/504, 358/527, 250/205, 250/226, 356/213, 356/218, 355/35, 355/67, 354/413, 354/430, 354/132, 348/602, 348/603, 348/655, 345/207, 362/4, 362/5
• US Class Current: 358/504
• CPC Class Codes: H04N 1/6011 with simulation on a subsidiary picture reproducer H04N1/622 takes precedence; matching two or more picture reproducers H04N1/6052
• CPC Class Codes: H04N 1/603 controlled by characteristics of the picture signal generator or the picture reproducer
• CPC Class Codes: H04N 1/6052 Matching two or more picture signal generators or two or more picture reproducers
• CPC Class Codes: H04N 1/6088 by viewing conditions, i.e. conditions at picture output

Abstract

A color printing system includes a central processing unit for generating color image data, a color monitor for displaying color image data generated by the central processing unit and a color temperature sensing device for sensing color temperature of viewing light in which color images displayed on the monitor and color images printed by the printer are viewed. A first light source has a light output intensity controllable by the central processing unit. The central processing unit is adapted to control the intensity of the first light source in accordance with the color temperature sensed by the sensing device so as to match the color temperature sensed by the sensing device to a potential color temperature. Additionally, a second light source may be provided. The second light source has a different color temperature than the first light source and the central processor can adjust the intensity of the first and second light source based on relative color temperatures. The central processing unit is adapted to adjust the color temperature of either or both intensity of the first and second light sources.

Claims

1. Apparatus for adjusting color temperature of viewing light to a white point of a color monitor, said apparatus comprising:

a first light source whose color temperature is adjustable;

means for measuring a color temperature of viewing light, the viewing light including ambient light and light output of said first light source;

means for comparing the color temperature measured by said measuring means with the white point of the color monitor; and

means for adjusting the color temperature of said first light source based on the comparison so that the color temperature of the viewing light is adjusted toward the white point of the color monitor.

2. Apparatus according to claim 1, further comprising a second light source whose color temperature is adjustable, said second light source having a color temperature different from the color temperature of said first light source.

3. Apparatus according to claim 2, wherein said adjusting means adjusts said first light source and said second light source based on a predetermined correlated color temperature of viewing light.

4. Apparatus according to claim 2, wherein the color temperature of said second light source is higher than the color temperature of said first light source, and wherein said adjusting means is adapted to increase the intensity of said second light source when the color temperature measured by said measuring means is low and to increase the intensity of said first light source when the color temperature measured by said measuring means is high.

5. Apparatus according to claim 1, wherein said first light source includes a controllable dimmer controllable by said adjusting means.

6. Apparatus according to claim 1, further comprising means for setting the pre-designated color temperature.

7. Apparatus according to claim 6, wherein said means for setting includes means for measuring the color temperature of a color monitor and wherein said pre-designated temperature is set to the color temperature of said color monitor.

8. A color printing system for adjusting a color temperature of viewing light to a white point of a color monitor, said color printing system comprising:

a central processing unit for generating color image data;

a first light source having a color temperature controllable by said central processing unit;

a color monitor for displaying color image data generated by said central processing unit;

a color printer for printing color image data generated by said central processing unit;

a color temperature sensing device for sensing color temperature of viewing light which includes ambient light and light output of the first light source and in which color images displayed on said color monitor and color images printed by said color printer are viewed;

wherein said central processing unit is adapted to control the color temperature of said first light source in accordance with the color temperature of the viewing light sensed by said color temperature sensing device so as to match the color temperature of the viewing light to the white point of the color monitor.

9. A color printing system according to claim 8, further comprising a second color sensing device for sensing the color temperature of said color monitor, wherein said central processing unit is adapted to set the predetermined color temperature to the color temperature sensed by said second color sensing device whereby color temperature of the viewing light is matched to the color temperature of the color monitor.

10. A color printing system according to claim 8, further comprising a second light source whose color temperature is controllable, said second light source having a color temperature different from the color temperature of said first light source.

11. A color printing system according to claim 10, wherein said central processing unit is adapted to adjust said first light source and said second light source based on a predetermined correlated color temperature of viewing light.

12. A color printing system according to claim 10, wherein the color temperature of said second light source is higher than the color temperature of said first light source, and wherein said central processing unit is adapted to increase the intensity of said second light source when the color temperature measured by said color temperature sensing device is low and to increase the intensity of said first light source when the color temperature measured by said color temperature sensing device is high.

13. A color printing system according to claim 8, wherein said central processing unit is adapted to control both the intensity of said first light source and said color monitor in accordance with the color temperature sensed by said sensing device so as to adjust the color temperature to a predetermined color temperature.

14. A color printing system according to claim 8, further comprising a color sensing device for sensing the color temperature of said color monitor wherein said central processing unit is adapted to adjust an output color image of the color printer so as to match the color temperature of the color monitor.

15. A color printing system according to claim 8, wherein said first light source includes a controllable dimmer controllable by the central processing unit.

16. A method for adjusting color temperature viewing light to a white point of a color monitor, said method comprising the steps of:

measuring a color temperature of viewing light, the viewing light including ambient light and light output of a first light source;

comparing the color temperature of the viewing light measured in the measuring step with the white point of the color monitor; and

adjusting the color temperature of the first light source based on the comparison in the comparison step so that the color temperature of the viewing light is adjusted toward the white point of the color monitor.

17. A method according to claim 16, further comprising the step of adjusting a color temperature of a second light source, said second light source having a color temperature different from the color temperature of the first light source.

18. A method according to claim 17, wherein the step of adjusting the first light source and the step of adjusting the second light source are based on a predetermined correlated color temperature of viewing light.

19. A color printing method for printing color images displayed on a color monitor, and for adjusting a color temperature of viewing light to a white point of the color monitor so that the printed color images are not perceptually different from the displayed color images, said color printing method comprising the steps of:

displaying a color image on a color monitor;

printing the color image displayed on the color monitor;

sensing a color temperature of viewing light, the viewing light including ambient light and light output of a first light source, and said viewing light being used to view the color image displayed in the displaying step and to view the color image printed in the printing step; and

controlling the color temperature of the first light source in accordance with the color temperature of the viewing light sensed in the sensing step so as to match the color temperature of the viewing light to the white point of the color monitor.

20. A method according to claim 19, further comprising the step of controlling a second light source, said second light source having a color temperature different from the color temperature of the first light source.

21. A method according to claim 20, wherein the step of controlling the first light source and the step of controlling the second light source are based on a predetermined correlated color temperature of viewing light.