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| XXX - Not complete. |
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| Name |
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| SGIX_ycrcba |
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| Name Strings |
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| GL_SGIX_ycrcba |
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| Version |
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| Last Modified Date: 01/16/1998 |
| $Date: 1998/01/16 21:47:41 $ $Revision: 1.2 $ |
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| Number |
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| 203 |
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| Dependencies |
| |
| This extension, combined with the subsample.spec |
| (SGIX_subsample) extension obsoletes the current ycrcb.spec |
| (SGIX_ycrcb) extension. Support of SGIX_ycrcb should be |
| accomplished using the SGIX_subsample and SGIX_ycrcba. |
| |
| EXT_texture3D affects the definition of this extension |
| EXT_subtexture affects the definition of this extension |
| EXT_histogram affects the definition of this extension |
| EXT_convolution affects the definition of this extension |
| SGI_color_table affects the definition of this extension |
| |
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| Overview |
| |
| This extension provides a method for OpenGL to read and store |
| images that are defined in standard YCRCB and YCRCBA video color |
| spaces. As with the CYMK extension, conversion to RGBA takes place |
| immediately following the unpack pixel store, and preceding the |
| pack pixel store operations, and is only available on transfers to |
| and from memory. The algorithms that convert between YCRCB and |
| RGBA are "black-box" in nature, and left undefined by the |
| extension, however it is recommended that conversion comply with |
| the CCIR standard. This extension specifies the format of a pixel |
| rectangle independent of component subsampling. Component |
| subsampling is specified using a separate extension. |
| |
| Two new formats are added, YCRCB_SGIX and YCRCBA_SGIX. |
| |
| YCRCB_SGIX is defined as a 3 component format representing the Cb, |
| Y, and Cr values per pixel. YCRCBA_SGIX is defined as a 4 component |
| format representing Cb, Y, Cr, and A values per pixel. |
| |
| As with the CMYK extension, this extension doesn't preclude the |
| possibility of other higher quality conversion methods. |
| |
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| New Procedures and Functions |
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| None |
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| New Tokens |
| |
| Accepted by the <format> parameter of DrawPixels, ReadPixels, |
| TexImage1D, TexImage2D, TexImage3DEXT, TexImage4DSGIS, TexSubImage1DEXT, |
| TexSubImage2DEXT, TexSubImage3DEXT, TexSubImage4DSGIS, GetTexImage, |
| ColorTableSGI, GetColorTableSGI, ConvolutionFilter1DEXT, |
| ConvolutionFilter2DEXT, ConvolutionFilter3DEXT, GetConvolutionFilterEXT, |
| SeparableFilter2DEXT, SeparableFilter3DEXT, GetSeparableFilterEXT, |
| GetHistogramEXT, and GetMinmaxEXT: |
| |
| YCRCB_SGIX 0x8318 |
| YCRCBA_SGIX 0x8319 |
| |
| Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation) |
| |
| None |
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| Additions to Chapter 3 of the 1.0 Specification (Rasterization) |
| |
| Two entries are added to table 3.5 (DrawPixels and ReadPixels formats): |
| |
| Target |
| Name Type Elements Buffer |
| ---- ---- -------- ------ |
| YCRCB_SGIX Component Cb chroma value, Color |
| Y luminance value, |
| Cr chroma value |
| |
| YCRCBA_SGIX Component Cb chroma value, Color |
| Y luminance value, |
| Cr chroma value, |
| A |
| |
| Table 3.5: DrawPixels and ReadPixels formats. The third column |
| gives a description of and the number and order of elements in a |
| group. |
| |
| The new formats YCRCB_SGIX and YCRCBA_SGIX are added to the |
| discussion of Conversion to RGB. If the format is either of these two |
| values, then the chroma and luminance values in each group are converted |
| to R, G, and B values using an undefined algorithm. |
| |
| Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations |
| and the Framebuffer) |
| |
| The new formats are added to the discussion of Obtaining Pixels from the |
| Framebuffer. |
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| The new formats are added to the discussion of Index Lookup. |
| |
| A new section, "Conversion to YCrCb," is added immediately |
| following the section "Conversion to L." Or "Conversion to L" is |
| expanded to cover conversion to L, YCrCb, and CMYK |
| |
| |
| Additions to Chapter 5 of the 1.0 Specification (Special Functions) |
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| None |
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| Additions to Chapter 6 of the 1.0 Specification (State and State Requests) |
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| None |
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| Additions to the GLX Specification |
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| None |
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| GLX Protocol |
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| None |
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| Errors |
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| None |
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| New State |
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| None |
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| New Implementation Dependent State |
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| None |
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