Claims
- 1. A method of modifying color in an n-bit system, wherein a digitally encoded representation of an original image in red-green-blue color space, the original image composed of pixels defined by the level of red, green and blue therein, each pixel defined by one of a number of encoded values of levels of red, green and blue, such number relatively large with respect to a desired number of levels for modifying the color of the original image, comprising the steps of:
- a) separating the original image into red, green and blue color separations, whereby for each separation, each pixel in the original image is defined by one of N different levels of red or green or blue at that pixel position;
- b) for each of the red, green and blue color separations, reducing the number of levels N defining pixels in each separation, to a value N.sub.R, N.sub.B, and N.sub.G, respectively, where N.sub.R .times.N.sub.B .times.N.sub.G is less than 2.sup.n ;
- c) producing a look up table having a number of entries equal to N.sub.R .times.N.sub.B .times.N.sub.G, each entry of the look up table consisting of one RGB triplet;
- d) combining the reduced number of levels N.sub.R, N.sub.B, and N.sub.G together to form an index for each pixel for which an RGB triplet in the look up table is selected;
- e) displaying the original image in terms of the reduced number of levels N.sub.R, N.sub.B, and N.sub.G on a display device;
- f) converting each RGB triplet in the look up table to a set of luminance and chrominance values, whereby each pixel identified as an RGB triplet is defined by a set of luminance and chrominance values;
- g) modifying the of each RGB triplet in the look up table, whereby each pixel identified as an RGB triplet is identified as a modified RGB triplet, whereby the overall appearance of the image is changed; and
- h) modifying each pixel of the original image defined by one of a relatively large number of encoded values of levels of red, green and blue, in accordance with the modifications to the set of luminance and chrominance values of each combination of N.sub.R, N.sub.B, and N.sub.G in the look up table.
- 2. The method as defined in claim 1, wherein the relatively large number of encoded values of levels of red, green and blue, is approximately (256).sup.3.
- 3. The method as defined in claim 1, wherein the number of levels N defining pixels in each separation is 256.
- 4. The method as defined in claim 1, wherein the number n is equal to 8.
- 5. The method as defined in claim 4, wherein N.sub.R, N.sub.B, and N.sub.G, are not necessarily equal, and 3.ltoreq.N.sub.R, N.sub.B, or N.sub.G .ltoreq.8.
- 6. The method as defined in claim 4, wherein for an N.sub.x of the group N.sub.R, N.sub.B, and N.sub.G, 3.ltoreq.N.sub.x .ltoreq.8.
- 7. The method as defined in claim 4, wherein 27.ltoreq.N.sub.R .times.N.sub.B .times.N.sub.G .ltoreq.120.
- 8. The method as defined in claim 4, wherein N.sub.R .times.N.sub.B .times.N.sub.G is between 90 and 100.
- 9. The method as defined in claim 4, wherein N.sub.R .times.N.sub.B .times.N.sub.G equals 96.
- 10. The method as defined in claim 1 wherein the step of reducing the number of levels N defining pixels in each separation, to the reduced number of levels N.sub.R, N.sub.B, and N.sub.G, respectively, where N.sub.R .times.N.sub.B .times.N.sub.G .ltoreq.2.sup.n, uses error diffusion among neighboring pixels to smooth artifacts arising from the reduction in levels from N to N.sub.R, N.sub.B, or N.sub.G.
- 11. A method of modifying color in a digitally encoded representation of an original image in red-green-blue color space, the original image composed of pixels defined by the level of red, green and blue therein, each pixel defined by one of a number of encoded values of levels of red, green and blue, such number relatively large with respect to a desired number of levels for modifying the color of the original image, the modifications to be performed on a digital computer, with a processor, a display, a display memory suitable for storing a set of values defining pixels in each separation representing 256 colors, and data entry arrangement, comprising the steps of:
- a) at the processor, separating the original image into red, green and blue color separations, whereby for each separation, each pixel in the original image is defined by one of N different values of red or green or blue at that pixel position;
- b) at the processor, for each of the red, green and blue color separations, reducing the number of values N defining pixels in each separation, to a value N.sub.R, N.sub.B, and N.sub.G, respectively, where 27.ltoreq.N.sub.R .times.N.sub.B .times.N.sub.G .ltoreq.120;
- c) in the display memory, producing a look up table having a number of entries equal to N.sub.R .times.N.sub.B .times.N.sub.G, each entry of the look up table consisting of one RGB triplet;
- d) in the processor, combining the reduced number of levels together to form an index for each pixel for which an RGB triplet is selected from the reduced color set;
- e) at the display, displaying the original image in terms of the reduced number of levels N.sub.R, N.sub.B, and N.sub.G ;
- f) with the processor, converting each RGB triplet in the look up table in the display memory to a set of luminance and chrominance values, whereby each pixel identified as an RGB triplet is defined by a set of luminance and chrominance values;
- g) with the data entry arrangement, entering modifications, to the set of luminance and chrominance values of each combination of N.sub.R, N.sub.B, and N.sub.G in the look up table, whereby each pixel identified as a combination of N.sub.R, N.sub.B, and N.sub.G is also modified, and entering the modifications into the look up table in the display memory, whereby the overall appearance of the displayed image is changed; and
- h) modifying each pixel of the original image defined by one of a relatively large number of encoded values of levels of red, green and blue, in accordance with the modifications to the set of luminance and chrominance values of each combination of N.sub.R, N.sub.B, and N.sub.G in the look up table.
- 12. The method as defined in claim 11, wherein the relatively large number of encoded values of levels of red, green and blue, is approximately (256).sup.3.
- 13. The method as defined in claim 11, wherein the number of levels defining pixels in each separation is 256.
- 14. The method as defined in claim 11, wherein N.sub.R, N.sub.B, and N.sub.G, are not necessarily equal, and 3.ltoreq.N.sub.R, N.sub.B, or N.sub.G .ltoreq.8.
- 15. The method as defined in claim 11, wherein for each N of N.sub.R, N.sub.B, and N.sub.G, 3.ltoreq.N.ltoreq.8.
- 16. The method as defined in claim 11, wherein N.sub.R .times.N.sub.B .times.N.sub.G is between 90 and 100.
- 17. The method as defined in claim 16, including the step of:
- displaying the modified original image, on the display device, by repeating steps a-d, for the modified original image.
- 18. The method as defined in claim 11, wherein N.sub.R .times.N.sub.B .times.N.sub.G equals 96.
- 19. The method as defined in claim 11 wherein the step of reducing the number of levels N defining pixels in each separation, to N.sub.R, N.sub.B, and N.sub.G, respectively, where 27<N.sub.R .times.N.sub.B .times.N.sub.G <120, uses error diffusion among neighboring pixels to smooth artifacts arising from the reduction in levels from N to N.sub.R, N.sub.B, or N.sub.G.
- 20. The method as defined in claim 11, including the step of:
- with the processor, modifying each pixel of the original image defined by one of the relatively large number of encoded values of levels of red, green and blue, in accordance with the modifications to the set of luminance and chrominance values of each combination of N.sub.R, N.sub.B, and N.sub.G in the look up table in the display memory.
- 21. A method of modifying color in a digitally encoded representation of an original image in red-green-blue color space, the original image composed of pixels defined by the level of red, green and blue therein, each pixel defined by one of a number of encoded values of levels of red, green and blue, such number relatively large with respect to a desired number of levels for modifying the color of the original image, the modifications to be performed on a digital computer, with a processor, a display, a display memory suitable for storing a set of values representing 256 colors, and data entry arrangement, comprising the steps of:
- a) at the processor, separating the original image into red, green and blue color separations, whereby for each separation, each pixel in the original image is defined by one of N different values of red or green or blue at that pixel position;
- b) at the processor, for each of the red, green and blue color separations, reducing the number of values N defining pixels in each separation, to a value N.sub.R, N.sub.B, and N.sub.G, respectively, where 27.ltoreq.N.sub.R .times.N.sub.B .times.N.sub.G .ltoreq.120;
- c) in the display memory, producing a look up table having a number of entries equal to N.sub.R .times.N.sub.B .times.N.sub.G, each entry of the look up table consisting of one RGB triplet;
- d) in the processor, combining the reduced number of levels together to form an index for each pixel for which an RGB triplet is selected from the reduced color set;
- e) at the display, displaying the original image in terms of the reduced number of levels N.sub.R, N.sub.B, and N.sub.G ;
- f) with the processor, converting each RGB triplet in the look up table in the display memory to a set of luminance and chrominance values, whereby each pixel identified as an RGB triplet is defined by a set of luminance and chrominance values;
- g) with the data entry arrangement, selecting a portion of the image;
- h) in the display memory, producing a look up table having a number of entries equal to N.sub.R .times.N.sub.B .times.N.sub.G for the selected area, each entry of the look up table consisting of one RGB triplet;
- i) in the processor, combining the reduced number of levels together to form an index for each pixel in the selected area for which an RGB triplet is selected from the reduced color set;
- j) with the data entry arrangement, entering modifications to the set of luminance and chrominance values of each combination of N.sub.R, N.sub.B, and N.sub.G in the second look up table, whereby each pixel in the selected area identified as a combination of N.sub.R, N.sub.B, and N.sub.G is also modified, and entering the modifications into the look up table in the display memory, whereby the appearance of the selected area of the displayed image is changed;
- k) modifying each pixel of the original image defined by one of a relatively large number of encoded values of levels of red, green and blue, in accordance with the modifications, if any, to the set of luminance and chrominance values of each combination of N.sub.R, N.sub.B, and N.sub.G in the look up table.
Parent Case Info
This is a continuation of application Ser. No. 07/517,895, filed May 2, 1990 is now abandoned.
US Referenced Citations (8)
Non-Patent Literature Citations (1)
Entry |
Floyd et al "An Adaptive Algorithm for Spatial Grayscale", pp. 75-77, 1976. |
Continuations (1)
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Number |
Date |
Country |
Parent |
517895 |
May 1990 |
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