Optional color space conversion

• US 7,973,802 B1
• Filed: 12/13/2007
• Issued: 07/05/2011
• Est. Priority Date: 09/13/2004
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Tynefield, John D. Jr., Tao, Andrew J., Bastos, Rui M., Rhoades, Johnny S.
• Primary Examiner(s): WASHBURN, DANIEL C
• Application Number:
  US11/956,298
• Time in Patent Office: 1,300 Days
• Field of Search: 345/604
• US Class Current: 345/604
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• 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: G09G 5/06 using colour palettes, e.g. look-up tables
• CPC Class Codes: G09G 5/363 Graphics controllers

Abstract

An apparatus and method for converting color data from one color space to another color space. A driver determines that a set of shader program instructions perform a color conversion function and the set of shader program instructions are replaced with either a single shader program instruction or a flag is set within an existing shader program instruction to specify that output color data is represented in a nonlinear color format. The output color data is converted to the nonlinear color format prior to being stored in a frame buffer. Nonlinear color data read from the frame buffer is converted to a linear color format prior to shading, blending, or raster operations.

Claims

1. A graphics system for performing color space conversion, comprising:

a shader pipeline configured to receive fragment data and produce shaded color data;

a raster operation unit configured to receive the shaded color data and perform raster operations to produce processed color data; and

a linear to nonlinear color conversion unit configured to receive the shaded color data or the processed color data and produce color data represented in a nonlinear color space, by;

selecting one or more color components of the shaded color data or processed color data for conversion to a color component in a nonlinear color space, wherein each of the selected color components include a sign, an exponent, and a mantissa,

for each color component selected, generating a corresponding color component in a nonlinear color space by;

generating an index to a look-up table based on a portion of the exponent of the selected color component,

based on the index, extracting from the look-up table a first color component represented in the nonlinear color space, and

clamping the first color component based on the sign and the portion of the exponent of the selected color component to produce a second color component represented in the nonlinear color space,

wherein the shader pipeline, the raster operation unit, and the linear to nonlinear color conversion unit are included in a graphics processor.

2. The graphics system of claim 1, further comprising a nonlinear to linear color conversion unit configured to receive color data read from a frame buffer and produce color data represented in a linear color space that is used to produce the processed color data, wherein the nonlinear to linear color conversion unit is included in the graphics processor.

3. The graphics system of claim 2, wherein the color data represented in the linear color space is used by the shader pipeline to produce the shaded color data.

4. The graphics system of claim 2, wherein the color data represented in the linear color space is used by the raster operation unit to produce the processed color data.

5. The graphics system of claim 2, wherein the linear color space is a RGB color space.

6. The graphics system of claim 2, wherein the nonlinear color space is a sRGB color space.

7. The graphics system of claim 1, wherein the linear to nonlinear color conversion unit is configured to process at least one color component within the shaded color data or the processed color data as specified by a shader program instruction.

8. The graphics system of claim 1, wherein the nonlinear color space is represented in a fixed point format.

9. The graphics system of claim 8, wherein the fixed point format is an 8-bit integer format.

10. The graphics system of claim 8, wherein the fixed point format is a 10-bit integer format.