Method for producing a color image and imaging device employing same
A method of producing a color image using a display comprised of pixels comprising red, green and blue primary color subpixels. The method comprises reducing the color gamut and increasing the brightness of the image relative to a base level, decreasing power to the display to reduce the brightness of the image, restoring color to the image to approximately the base level by modifying image pixel data using a three-dimensional lookup table to produce output image pixel data, and communicating the output image pixel data to the display. The display may be an LCD display, an LED display, an OLED display, a plasma display, and a DMD projector. Reducing the color gamut and increasing the brightness of the image may be accomplished by adding white to the image. The white may be added adaptively according to an algorithm by which the amount of white added decreases with increasing color saturation.
1. A method of producing a color image using a display device comprised of display pixels comprising groups of red, green and blue primary color subpixels, the method comprising:
a) providing data of an input image comprised of image pixels comprising red, green, and blue primary colors, to at least one of a computer readable storage medium, memory, or central processing unit of an imaging color rendering controller in communication with the display device;
b) within at least one of an external processor, or the computer readable storage medium, memory, or central processing unit of the image color rendering controller, generating a first three-dimensional look-up table of addresses containing values of input colors and corresponding output colors, wherein the input colors are defined by tristimulus values of the red, green, and blue primary colors, and wherein for each input color tristimulus value, a corresponding output color is defined;
c) via the central processing unit, loading the first three-dimensional look-up table into the image color rendering controller;
d) in the central processing unit, executing an image processing algorithm to:
increase the brightness of the image relative to a base brightness level by changing display device primary colors;
decrease power to the display device below a base power level to reduce the brightness of the image; and
restore color to the image to approximately the base brightness level by modifying image pixel data using the three-dimensional lookup table to produce output image pixel data; and
e) outputting the output image pixel data to the display pixels of the display device to produce the color image having a brightness at least as high as the base brightness level while operating the display device at a power level lower than the base power level.
2. The method of claim 1 , further comprising adding white to the color image to reduce the color gamut and increase the brightness of the color image.
3. The method of claim 2 , wherein white is added to at least one of the primary color subpixels of each group of primary color subpixels.
4. The method of claim 2 , wherein white is added to two of the three primary color subpixels of each group of primary color subpixels.
5. The method of claim 2 , wherein white is added to each of the red, green and blue primary color subpixels.
6. The method of claim 5 , wherein white is added to the red, green, and blue primary color subpixels of each group of primary color subpixels in unequal amounts.
7. The method of claim 5 wherein white is added adaptively according to an adaptive algorithm by which the amount of white added decreases with increasing color saturation of the image pixels of the input image.
8. The method of claim 7 , wherein the adaptive algorithm includes a Gaussian function that defines the decrease in white with increasing color saturation.
9. The method of claim 7 , wherein the adaptive algorithm is used to define the values of the output colors in the three-dimensional lookup table.
10. The method of claim 7 , wherein the adaptive algorithm includes determining the amount of white to add to each image display pixel and the amount of the decrease in power to each image display pixel.
11. The method of claim 10 , wherein a plurality of color images are produced using the display device.
12. The method of claim 11 , wherein the plurality of color images are produced by providing a plurality of input images to the at least one of the computer readable storage medium, memory, or central processing unit of the imaging color rendering controller, and wherein the image processing and adaptive algorithms are executed on each of the input images to produce the plurality of color images.
13. The method of claim 12 , wherein the adaptive algorithm further includes sensing the color saturation of each of the input images, and for each input image, increasing the brightness, decreasing power to the display device, and restoring color based upon the color saturation of that image.
14. The method of claim 12 , wherein the plurality of input images are provided from at least two image sources.
15. The method of claim 12 , wherein the plurality of input images is a time sequence of images selected from a video or a movie.
16. The method of claim 7 , wherein the adaptive algorithm includes determining the amount of white added for each individual image pixel.
17. The method of claim 16 , wherein the adaptive algorithm includes determining the amount of white added for each individual red, green and blue primary color subpixel.
18. The method of claim 2 , wherein white is added to the subpixels during a portion of a pixel exposure time.
19. The method of claim 1 , wherein the display device is one of an LCD display device, an LED display device, an OLED display device, a plasma display device, and a DMD projector.
20. The method of claim 1 , wherein the restoring the color to the image is performed in the IPT uniform hue color space.