Method and system for characterizing color display monitor output

• US 6,847,376 B2
• Filed: 03/15/2001
• Issued: 01/25/2005
• Est. Priority Date: 11/13/1998
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: LightSurf Technologies, Inc. (VeriSign, Inc.)
• Inventors: Engeldrum, Peter G., Strother, Thomas L., Hilliard, William J., Mattox, Joel D., Deutch, James E., Bernard, Peter, van Prooijen, Cornelis P.
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): BLACKMAN, ANTHONY J
• Application Number:
  US09/809,385
• Publication Number:
  US 20020041287A1
• Time in Patent Office: 1,412 Days
• Field of Search: 345/589, 345/590, 345/207, 345/600, 345/89, 348/674, 348/441, 358/504, 358/519, 382/167, 347/242
• US Class Current: 345/600
• CPC Class Codes: G06F 3/14 Digital output to display device ; Cooperation and interconnection of the display device with other functional units
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2370/027 Arrangements and methods specific for the display of internet documents
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/32512 of different type, e.g. internal and external devices
• CPC Class Codes: H04N 1/32529 of different type, e.g. internal and external devices

Abstract

The present invention provides a technique for modeling the tone reproduction curve of a flat panel screen such as an LCD. The technique employs a second order function to predict the luminance output as a function of the input voltage based upon two known input values. This abstract is provided for the sole purpose of complying with the rules requiring an abstract to allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure contained herein. This abstract is submitted with the express understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.

Claims

1. A method for predicting the color output of a display device as a second order function of the input voltage to the device, comprising:

obtaining the input voltage value required to display on the device each of at least two images having known luminance values; and

solving the function as at least two simultaneous equations based on the obtained input voltage values to calculate the two powers for the function to describe the device tone reproduction curve.

2. The method of claim 1, wherein obtaining the input voltage values comprises:

obtaining input voltage values required to display on the device images having known luminance values from the interaction of a viewer with the images having known luminance values on the device.

3. The method of claim 2, wherein obtaining the input voltage values from the interaction of a viewer with the images having known luminance values on the device comprises:

presenting a plurality of continuous tone images for matching with each image having a known luminance value, each continuous tone image corresponding to a different pre-selected input voltage; and

for each input voltage value, using the input voltage of the continuous tone image selected by the viewer.

4. The method of claim 1, wherein obtaining input voltage values comprises:

measuring the color output of the device when the images having known luminance values are displayed on the device.

5. The method of claim 4, wherein measuring the color output of the device comprises:

measuring the color output of the device with a spectrometer.

6. The method of claim 1, wherein solving the function comprises:

solving the function $L={\left[1-{\cos <br><br>\left(\frac{\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>x}{2}\right)}^p\right]}^{r/1.75}$

 

wherein L is the luminance, x is the obtained input voltage value, and p and rare the two power parameters of the function.

7. The method of claim 6, wherein solving the function further comprises:

scaling the function to account for one or more factors selected from the group of factors including black point cutoff, ambient light, absolute luminance, absolute radiance, and absolute irradiance.

8. The method of claim 1, wherein obtaining the input voltage values comprises:

obtaining the input voltage value required to display on the device each of an image having a luminance value of ⅓

of the maximum device luminance and an image having a luminance value of ⅔

of the maximum device luminance.

9. The method of claim 1, further comprising:

adjusting characteristics of an image in accordance with the device tone reproduction curve for display on the device.

10. The method of claim 9, wherein adjusting characteristics of the image comprises:

adjusting characteristics of the image in accordance with differences between the device tone reproduction curve and a predetermined tone reproduction curve.

11. The method of claim 1, wherein the display device is selected from the group including liquid crystal displays (LCD), plasma screens, gas-discharge screens, cathode ray tube (ORT) monitors, light emitting diodes (LED), organic LED, and electroluminescent displays.

12. The method of claim 6, wherein the display device is a cathode ray tube monitor and solving the function comprises:

setting the power parameter ρ

equal to 1.

13. A method for displaying color images on a display device, comprising:

solving a second order function for predicting the device tone reproduction curve as at least two simultaneous equations based on input voltage values required to display images on the device having known luminance values;

adjusting characteristics of the images in accordance with the tone reproduction curve described by the second order function; and

providing the adjusted images for display on the device.

14. The method of claim 13, wherein solving the function comprises:

calculating the two powers for the function to predict the device tone reproduction curve.

15. The method of claim 14, further comprising:

obtaining input voltage values required to display on the device images having known luminance values from the interaction of a viewer with the images having known luminance values on the device.

16. The method of claim 15, wherein obtaining the input voltage values from the interaction of a viewer with the images having known luminance values on the device comprises:

presenting a plurality of continuous tone images for matching with each image having a known luminance value, each continuous tone image corresponding to a different pre-selected input voltage; and

for each input voltage value, using the pre-selected input voltage of the continuous tone image selected by the viewer.

17. The method of claim 14, wherein obtaining input voltage values comprises:

measuring the color output of the device when the images having known luminance values are displayed on the device.

18. The method of claim 17, wherein measuring the color output of the device comprises:

measuring the color output of the device with a spectrometer.

19. The method of claim 14, wherein solving the function comprises:

solving the function $L={\left[1-{\cos <br><br>\left(\frac{\mathrm{\pi <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>x}{2}\right)}^p\right]}^{r/1.75}$

 

wherein L is the luminance, x is the obtained input voltage value, and p and r are the two power parameters of the function.

20. The method of claim 19, wherein solving the function further comprises:

scaling the function to account for one or more factors selected from the group of factors including black point cutoff, ambient light, absolute luminance, absolute radiance, and absolute irradiance.

21. The method of claim 14, wherein solving the function comprises:

solving the function based on the input voltage value required to display on the device each of an image having a luminance value of ⅓

of the maximum device luminance and an image having a luminance value of ⅔

of the maximum device luminance.

22. The method of claim 19 wherein adjusting characteristics of images comprises:

adjusting characteristics of each image in accordance with differences between the device tone reproduction curve and a predetermined tone reproduction curve.

23. The method of claim 14, wherein the display device is selected from the group including liquid crystal displays (LCD), plasma screens, gas-discharge screens, cathode ray tube (CRT) monitors, light emitting diodes (LED), organic LED, and electroluminescent displays.

24. The method of claim 19, wherein the display device is a cathode ray tube monitor and solving the function comprises:

setting the power parameter ρ

equal to 1.