Weighted mapping of color value information onto a display screen

• US 4,991,122 A
• Filed: 08/31/1989
• Issued: 02/05/1991
• Est. Priority Date: 10/07/1987
• Status: Expired due to Fees

• Current Assignee: General Parametrics Corp. (Sims Ltd.)
• Original Assignee: General Parametrics Corp. (Sims Ltd.)
• Inventors: Sanders, Eugene T.
• Primary Examiner(s): Harkcom, Gary V.
• Assistant Examiner(s): Zimmerman, Mark K.
• Application Number:
  US07/401,580
• Time in Patent Office: 523 Days
• Field of Search: 364/518, 364/521, 340/701, 340/703, 340/731
• US Class Current: 345/698
• CPC Class Codes: G06T 11/001 Texturing; Colouring; Generation of texture or colour inpainting G06T5/77
• CPC Class Codes: G09G 3/2051 with use of a spatial dither pattern
• 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

Abstract

A method and apparatus for assigning color values (or gray scale) to picture display locations. A large frame buffer is written into with each memory location (preferably one bit) corresponding to a separate element of an image. The frame buffer contents are then mapped into a smaller space. The frame buffer memory has a color value assigned to each location of the memory. The memory has a larger number of locations than the number of color picture display locations. Each location is also assigned one of a plurality of weights. A number of color patterns are created and stored, with each color pattern being a bit pattern designed to produce the desired color when applied to the color values of the memory locations. A representation of a desired image is written into the memory using the color patterns, with each memory location corresponding to a separate element of the image. A group of bits in adjacent memory locations are combined with their weighting factors to produce each color value for each color picture display location.

Claims

1. A method for mapping a source image onto a display having a smaller number of display locations than said source image comprising the steps of:

assigning, in accordance with a first predetermined pattern, one of a plurality of color/gray scale values to each location in a frame buffer, each color/gray scale value being assigned to a number of locations greater than the number of display locations, said predetermined pattern intermixing said color/gray scale values such that each color/gray scale value for each display location is represented by a plurality of frame buffer locations separated by at least one location in either a row or column direction;

assigning, in accordance with a second predetermined pattern, one of a plurality of weights to each said location in said frame buffer;

creating a plurality of color/gray scale patterns, each color/gray scale pattern being a bit pattern designed to produce a desired color or shade of gray when combined in accordance with said color/gray values and weights assigned to said frame buffer locations;

writing a representation of said source image into said frame buffer using said color/gray scale patterns such that a plurality of separate elements of said source image are mapped onto a block of proximate frame buffer locations used to represent a single display location; and

separately combining, to produce a total amount of each color/gray scale value for each display location, from a block of proximate frame buffer locations corresponding to said display location, bits stored in locations which were assigned to said color/gray scale value, each bit being manipulated outside of said frame buffer to give its assigned weight, to produce said total amount of said color/gray scale value for said display location.

2. The method of claim 1 wherein said color/gray scale values comprise luminance (Y), blue color difference (U) and red color difference (V).

3. The method of claim 2 wherein two frame buffer locations are assigned to luminance (Y) for every one assigned to blue color difference (U), and one frame buffer location is assigned to red color difference (V) for every one assigned to blue color difference (U).

4. The method of claim 3 wherein each color value has a weight of one of 4, 2 and 1.

5. The method of claim 4 wherein said Y values are assigned to alternate locations of said image in said memory in a checkerboard pattern, with every Y value in half of the diagonals formed by said checkerboard pattern in a first direction having a weight of 4.

6. The method of claim 5 wherein said U value is assigned to locations along every fourth diagonal formed by said checkerboard pattern in a second direction, with U values in alternate fourth diagonals having a weight of 4, said V value being assigned to a diagonal intermediate every said fourth U diagonal.

7. The method of claim 4 wherein half of the locations for each color value are assigned a weight of 4.

8. The method of claim 7 wherein said combining step further includes receiving a bit from two locations having a weight of 4, one location having a weight of 2 and one location having a weight of 1, and creating a 4-bit digital value with said weight 1 bit in the least significant position followed by said weight 2 bit, an exclusive OR function of said two weight 4 bits and an AND function of said two weight 4bits.

9. The method of claim 8 further comprising the steps of:

converting said 4-bit digital value into analog signal; and

converting said analog signal into an RGB signal.

10. The method of claim 1 wherein each frame buffer location corresponds to a separate element of said source image.

11. The method of claim 1 wherein, for at least one of said color/gray scale values, at least two color/gray scale values for a single display location have the same weight assigned.

12. An apparatus for mapping a source image into a display having a smaller number of display locations than said source image, comprising:

a frame buffer, each location of said frame buffer being assigned, in accordance with a predetermined pattern, to one of a plurality of color/gray scale values such that each color/gray scale value is assigned to a number of locations greater than the number of said display locations, said predetermined pattern intermixing said color/gray scale values such that each color/gray scale value for each display location is represented by a plurality of frame buffer locations separated by at least one location in either a row or column direction;

means for producing a plurality of color/gray scale patterns, each color/gray scale pattern being a bit pattern designed to produce a desired amount of said color or shade of gray when combined in accordance with said color/gray scale values and weights assigned to said frame buffer locations;

means for writing a representation of said source image into said frame buffer using said color/gray scale patterns such that a plurality of separate elements of said source image are mapped onto a block of proximate frame buffer locations used to represent a single display location; and

means for separately combining, to produce a total amount of each color/gray value, for each display location, from a block of proximate frame buffer locations corresponding to said display location, bits stored in locations which were assigned to said color/gray scale value, each bit being modified by its assigned weight, to produce said total amount of said color/gray scale value for said display location.

13. The apparatus of claim 12 wherein said color/gray scale values comprise luminance (Y), blue color difference (U) and red color difference (V).

14. The apparatus of claim 13 wherein two frame buffer locations are assigned to luminance (Y) for every one assigned to blue color difference (U), and one frame buffer location is assigned to red color difference (V) for ever one assigned to blue color difference (U). difference (V) for every one assigned to blue color difference (U).

15. The apparatus of claim 14 wherein each color value has a weight of one of 4, 2 and 1.

16. The apparatus of claim 15 wherein said Y values are assigned to alternate locations of said image in said memory in a checkerboard pattern, with every Y value in half of the diagonals formed by said checkerboard pattern in a first direction having a weight of 4.

17. The apparatus of claim 16 wherein said U value is assigned to locations along every fourth diagonal formed by said checkerboard pattern in a second direction, with U values in alternate fourth diagonals having a weight of 4, said V value being assigned to a diagonal intermediate every said fourth U diagonal.

18. The apparatus of claim 15 wherein half of the locations for each color value are assigned a weight of 4.

19. The apparatus of claim 18 wherein said means for combining further includes means for receiving a bit from two locations having a weight of 4, one location having a weight of 2 and one location having a weight of 1, and creating a 4-bit digital value with said weight 1 bit in the least significant position followed by said weight 2 bit, an exclusive OR function of said two weight 4 bits and an AND function of said two weight 4 bits.

20. The apparatus of claim 19 further comprising:

means for converting said 4-bit digital value into analog form; and

means for converting said YUV signals into RGB signals.

21. The apparatus of claim 12 wherein each frame buffer location corresponds to a separate element of said source image.

22. The apparatus of claim 12 wherein, for at least one of said color/gray scale values, at least two color/gray scale values for a single display location have the same weight assigned.

23. An apparatus for mapping a source image having YUV color values onto a color picture display having a smaller number of color picture display locations to condense said source image, comprising:

a frame buffer having a first portion for storing an image, each location of said first portion being assigned, in accordance with a first predetermined pattern, to one of Y, U and V color values such that each color value is assigned to a number of locations greater than the number of said color picture display locations and said Y value is assigned to twice as many locations as said U value, and said V value is assigned to an equal number of memory locations as said U value, said predetermined pattern intermixing said color values such that each color value for each display location is represented by a plurality of frame buffer locations separated by at least one location in either a row or column direction;

a plurality of color patterns stored in a second portion of said frame buffer, each color pattern being a bit pattern designed to produce a desired amount of said color when combined in accordance with said color values and weights assigned to said locations in said first portion of said frame buffer;

processing means for writing a representation of said source image into said first portions of said frame buffer using said color patterns from said second portions of said frame buffer such that a plurality of separate elements of said source image are mapped onto a block of proximate frame buffer locations used to represent a single display location;

weighting and decoding means for separately combining, to produce a total amount of each color value, for each display location from a block of proximate frame buffer locations corresponding to said display location, bits stored in locations which were assigned to said color value, each bit being modified by its assigned weight, to produce said total amount of said color value for said color picture display location;

three digital to analog converters coupled to receive said total amount for the Y, U and V color values, respectively; and

means for converting said total amount of said Y, U and V values to RGB values.

24. An apparatus for mapping a source image having YUV color values onto a color picture display having a smaller number of color picture display locations to condense said source image, comprising:

a frame buffer for storing an image, each location of said frame buffer being assigned, in accordance with a first predetermined pattern, to one of Y, U and V color values such that each pair of picture display location there is

a first block of buffer locations having a plurality of locations assigned a V value, with each V value in said block being separated from a next V value by at least one location in both the row and column directions, said first block including V values in at least two rows,

said first block including a plurality of locations assigned a U value, with each U value in said block being separated from a next U value by at least one location in both the row and column directions, said first block including U values in at least two rows,

said first block including two halves, each half block including a plurality of locations assigned a Y value, with each Y value in said block being separated from a next Y value by at least one location in both the row and column directions, each of said halves including Y values in at least two rows,

such that each display location may have a different Y value but each pair of display locations will have the same U and V values;

a plurality of color patterns stored in a color pattern memory, each color pattern being a bit pattern designed to represent a desired amount of said color when combined in accordance with said color values and weights assigned to said locations in said first portion of said frame buffer;

processing means for writing a representation of said source image into said frame buffer using said color patterns from said color pattern memory such that a plurality of separate elements of said source image are mapped onto each half block of proximate frame buffer locations used to represent a single display location;

weighting and decoding means for separately combining, to produce a total amount of each color value, for each display location from a block of proximate frame buffer locations corresponding to said display location, bits stored in locations which were assigned to said color value, each bit being modified by its assigned weight, to produce said total amount of said color value for said color picture display location;

three digital to analog converters coupled to receive said total amount for the Y, U and V color values, respectively; and

means for converting said total amount of said Y, U and V values to RGB values.

25. An apparatus for mapping a source image onto a display having a smaller number of display locations than said source image comprising the steps of:

assigning, in accordance with a first predetermined pattern one of a plurality of color/gray scale values to each location in a frame buffer, each color/gray scale value being assigned to a number of locations greater than the number of display locations, said predetermined pattern intermixing said color/gray scale values such that each color/gray scale value for each display location is represented by a plurality of frame buffer locations separated by at least one location in both a row and a column direction, with each color value for each display location being represented by at least two frame buffer locations in at least two rows;

assigning, in accordance with a second predetermined pattern, one of a plurality of weights to each said location in said frame buffer;

creating a plurality of color/gray scale patterns, each color/gray scale pattern being a bit pattern designed to produce a desired color or shade of gray when combined in accordance with said color/gray values and weights assigned to said frame buffer locations;

writing a representation of said source image into said frame buffer using said color/gray scale patterns such that a plurality of separate elements of said source image are mapped onto a block of proximate frame buffer locations used to represent a single display location; and

separately combining, to produce a total amount of each color/gray scale value for each display location, from a block of proximate frame buffer locations corresponding to said display location, bits stored in locations which were assigned to said color/gray scale value, each bit being manipulated outside of said frame buffer to give its assigned weight, to produce said total amount of said color/gray scale value for said display location.