| Name |
| |
| OML_resample |
| |
| Name Strings |
| |
| GL_OML_resample |
| |
| Contact |
| |
| Jon Leech, Silicon Graphics (ljp 'at' sgi.com) |
| |
| Status |
| |
| Complete. Approved by the Khronos SIG on July 19, 2001. |
| |
| Version |
| |
| Last Modified Date: 07/23/2001 |
| Author Revision: $Header: //depot/main/doc/registry/extensions/OML/resample.spec#10 $ |
| |
| Number |
| |
| 241 |
| |
| Dependencies |
| |
| OML_subsample is required. |
| This extension is written against the OpenGL 1.2.1 Specification, |
| |
| Overview |
| |
| This extension enhances the resampling capabilities of the |
| OML_subsample extension. It is loosely based on the SGIX_resample |
| extension. |
| |
| When converting data from subsampled to uniform sampling, upsampling |
| may be performed by one of three methods: component replication, |
| zero fill, or adjacent neighbor averaging. |
| |
| When converting data from uniform sampling to subsampled form, |
| downsampling may be performed only by component decimation (point |
| sampling) or averaging. |
| |
| Upsampling and downsampling filters other than those defined by this |
| extension may be performed by appropriate use of convolution and |
| other pixel transfer operations. The zero fill unpacking mode is |
| included to assist applications wanting to define their own filters. |
| |
| Issues |
| |
| * Should RESAMPLE_xxx enums be renamed to PIXEL_RESAMPLE_xxx? |
| |
| IP Status |
| |
| No known issues. |
| |
| New Procedures and Functions |
| |
| None. |
| |
| New Tokens |
| |
| Accepted by the <pname> parameter of PixelStoref, PixelStorei, |
| GetBooleanv, GetIntegerv, GetFloatv and GetDoublev: |
| |
| PACK_RESAMPLE_OML 0x8984 |
| UNPACK_RESAMPLE_OML 0x8985 |
| |
| Accepted by the <param> parameter of PixelStoref and PixelStorei |
| when the <pname> parameter is UNPACK_RESAMPLE_OML: |
| |
| RESAMPLE_REPLICATE_OML 0x8986 |
| RESAMPLE_ZERO_FILL_OML 0x8987 |
| RESAMPLE_AVERAGE_OML 0x8988 |
| |
| Accepted by the <param> parameter of PixelStoref and PixelStorei |
| when the <pname> parameter is PACK_RESAMPLE_OML: |
| |
| RESAMPLE_DECIMATE_OML 0x8989 |
| RESAMPLE_AVERAGE_OML 0x8988 |
| |
| |
| Additions to Chapter 2 of the OpenGL 1.2.1 Specification (OpenGL Operation) |
| |
| None. |
| |
| Additions to Chapter 3 of the OpenGL 1.2.1 Specification (Rasterization) |
| |
| - (3.6.1, p. 75 "Pixel Storage Modes") |
| |
| Add to table 3.1 (p. 76): |
| |
| Parameter Name Type Initial Value Valid Range |
| -------------- ---- ------------- ----------- |
| UNPACK_RESAMPLE_OML integer RESAMPLE_REPLICATE_OML RESAMPLE_REPLICATE_OML |
| RESAMPLE_ZERO_FILL_OML |
| RESAMPLE_AVERAGE_OML |
| |
| PACK_RESAMPLE_OML integer RESAMPLE_DECIMATE_OML RESAMPLE_DECIMATE_OML |
| RESAMPLE_AVERAGE_OML |
| |
| |
| - (3.6.4, p. 88 "Rasterization of Pixel Rectangles") |
| |
| - Modify the new subsection "Conversion to Uniform Sampling" |
| (introduced by OML_subsample) to read: |
| |
| Conversion to Uniform Sampling |
| |
| This step is applied only to subsampled data. If <format> is |
| FORMAT_SUBSAMPLE_24_24_OML, then the number of components per pixel |
| is increased from two to three. If <format> is |
| FORMAT_SUBSAMPLE_244_244_OML. then the number of components per |
| pixel is increased from three to four. The upsampling method used is |
| determined by the value of the PixelStore parameter |
| UNPACK_RESAMPLE_OML. |
| |
| After conversion to uniform sampling (see figure 3.9). pixels are |
| thereafter treated as though they were RGB (three component) or RGBA |
| (four component) format. |
| |
| In the remainder of this section, the j'th component of the i'th |
| pixel in a row is denoted by S_i,j (for source pixels in client |
| memory) and D_i,j (for destination pixels in the color buffer). |
| |
| Replication |
| |
| If the value of UNPACK_RESAMPLE_OML is RESAMPLE_REPLICATE_OML (see |
| figure 3.9), destination component values are defined as: |
| |
| For even pixels ((i mod 2) == 0): |
| |
| D_i,0 = S_i,0 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i+1,0 |
| D_i,3 = S_i,2 |
| |
| For odd pixels ((i mod 2) == 1): |
| |
| D_i,0 = S_i-1,0 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i,0 |
| D_i,3 = S_i,2 |
| |
| |
| - (figure 3.9, introduced by OML_subsample, is unchanged) |
| |
| Zero Fill |
| |
| If the value of UNPACK_RESAMPLE_OML is RESAMPLE_ZERO_FILL_OML (see |
| figure 3.10), destination component values are defined as: |
| |
| For even pixels ((i mod 2) == 0): |
| |
| D_i,0 = S_i,0 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i+1,0 |
| D_i,3 = S_i,2 |
| |
| For odd pixels ((i mod 2) == 1): |
| |
| D_i,0 = 0 |
| D_i,1 = S_i,1 |
| D_i,2 = 0 |
| D_i,3 = S_i,2 |
| |
| - Add new figure 3.10, following the new figure 3.9 defined in the |
| OML_subsample extension: |
| |
| FORMAT_SUBSAMPLE_24_24_OML: |
| <Cb0,Y0> <Cr0,Y1> <Cb2,Y2> <Cr2, Y3> |
| | | | | | | | | |
| | | ____/ | | | ____/ | |
| | | / | | | / | |
| | | | 0.0 | 0.0 | | | 0.0 | 0.0 |
| | | | | | | | | | | | | |
| V V V V V V V V V V V V |
| <Cb0,Y0,Cr0> <Cb0,Y1,Cr0> <Cb2,Y2,Cr2> <Cb2,Y3,Cr2> |
| < R0,G0,B1 > < R0,G1,B1 > < R2,G2,B3 > < R2,G3,B3 > |
| |
| FORMAT_SUBSAMPLE_244_244_OML: |
| <Cb0,Y0,A0> <Cr0,Y1,A1> <Cb2,Y2,A2> <Cr2,Y3,A3> |
| | | \ | | \ | | \ | | \ |
| | | _\_____/ | \ | | _\_____/ | \ |
| | | / \ | \ | | / \ | \ |
| | | | \ 0.0 | 0.0 \ | | | \ 0.0 | 0.0 \ |
| | | | | | | | | | | | | | | | | |
| V V V V V V V V V V V V V V V V |
| <Cb0,Y0,Cr0,A0> <Cb0,Y1,Cr0,A1> <Cb2,Y2,Cr2,A2> <Cb2,Y3,Cr2,A3> |
| < R0,G0,B1,A0 > < R0,G1,B1,A1 > < R2,G2,B3,A2 > < R2,G3,B3,A3 > |
| |
| |
| Figure 3.10: Upsampling with zero fill of subsampled data from host |
| memory to form RGB or RGBA pixels. |
| |
| |
| Averaging |
| |
| If the value of UNPACK_RESAMPLE_OML is RESAMPLE_AVERAGE_OML (see |
| figure 3.11), destination component values are defined as: |
| |
| For even pixels: |
| |
| D_i,0 = S_i,0 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i+1,0 |
| D_i,3 = S_i,2 |
| |
| (No special case for D_i,2 can arise when i is the last pixel, |
| because of the restriction to even image widths). |
| |
| For odd pixels: |
| |
| D_i,0 = S_i,0 i == <width>-1 (last pixel) |
| = 1/2 S_i-1,0 + 1/2 S_i+1,0 otherwise |
| D_i,1 = S_i,1 |
| D_i,2 = S_i,0 i == <width>-1 (last pixel) |
| = 1/2 S_i,0 + 1/2 S_i+2,0 otherwise |
| D_i,3 = S_i,2 |
| |
| - Add new figure 3.11, following the new figure 3.10: |
| |
| FORMAT_SUBSAMPLE_24_24_OML: |
| <Cb0,Y0> <Cr0,Y1> <Cb2,Y2> <Cr2, Y3> |
| | | | | | | | | |
| | | ____/ \__|__ ____|___|_______/ \__|__ _ |
| | | / | \/ | | / | \/ |
| |\_|__|_____ __|__|___ /|\__|__|_____ __|__|__ |
| | | | \/ | | | | | \/ | | |
| V V V V V V V V V V V V |
| <Cb0,Y0,Cr0> <Cb0,Y1,Cr0> <Cb2,Y2,Cr2> <Cb2,Y3,Cr2> |
| < R0,G0,B1 > < R0,G1,B1 > < R2,G2,B3 > < R2,G3,B3 > |
| |
| |
| FORMAT_SUBSAMPLE_244_244_OML: |
| <Cb0,Y0,A0> <Cr0,Y1,A1> <Cb2,Y2,A2> <Cr2,Y3,A3> |
| | | \ | | \ | | \ | | \ |
| | | _\_____/ \__|__ \______|___|____\______/ \__|__ \___ |
| | | / \ | \/ \ | | / \ | \/ \ |
| |\_|__|___\____ __|__|___\___/|\__|__|___\_____ __|__|___\_ |
| | | | | \/ | | | | | | | \/ | | | |
| V V V V V V V V V V V V V V V V |
| <Cb0,Y0,Cr0,A0> <Cb0,Y1,Cr0,A1> <Cb2,Y2,Cr2,A2> <Cb2,Y3,Cr2,A3> |
| < R0,G0,B1,A0 > < R0,G1,B1,A1 > < R2,G2,B3,A2 > < R2,G3,B3,A3 > |
| |
| Figure 3.11: Upsampling with averaging of subsampled data from host |
| memory to form RGB or RGBA pixels. |
| |
| Additions to Chapter 4 of the OpenGL 1.2.1 Specification (Per-Fragment |
| Operations and the Frame Buffer) |
| |
| - Modify the new section "Conversion to Subsampled Form" (introduced |
| by OML_subsample) to read: |
| |
| Conversion to Subsampled Form |
| |
| This step is applied only if <format> is FORMAT_SUBSAMPLE_24_24_OML |
| or FORMAT_SUBSAMPLE_244_244_OML. A filter operation specified by the |
| value of PACK_RESAMPLE_OML is applied prior to the subsampling step. |
| |
| In the remainder of this section, the j'th component of the i'th |
| pixel in a row is denoted by S_i,j (for source pixels in the color |
| buffer) and D_i,j (for destination pixels in client memory). |
| |
| If <format> is FORMAT_SUBSAMPLE_24_24_OML, then the resulting pixels |
| have 2 components (see figure 4.3); if <format> is |
| FORMAT_SUBSAMPLE_244_244_OML, then the resulting pixels have 3 |
| components (see figure 4.4). |
| |
| Decimation |
| |
| If the value of PACK_RESAMPLE_OML is RESAMPLE_DECIMATE_OML, then |
| destination component values are defined as: |
| |
| For even pixels ((i mod 2) == 0): |
| |
| D_i,0 = S_i,0 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i,3 (only for FORMAT_SUBSAMPLE_244_244_OML) |
| |
| For odd pixels ((i mod 2) == 1): |
| |
| D_i,0 = S_i-1,2 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i,3 (only for FORMAT_SUBSAMPLE_244_244_OML) |
| |
| - Add new figure 4.3 (renumber following figures): |
| |
| FORMAT_SUBSAMPLE_24_24_OML: |
| <R0,G0,B0,A0> <R1,G1,B1,A1> <R2,G2,B2,A2> <R3,G3,B3,A3> |
| | | | | | | | | | | | | | | | | |
| | | \ * * | * * | | \ * * | * * |
| | | | | | | | | |
| V V V V V V V V |
| <Cb0,Y0><Cr0, Y1> <Cb2,Y2><Cr2, Y3> |
| <--- pixel pair ----> <--- pixel pair ----> |
| |
| FORMAT_SUBSAMPLE_244_244_OML: |
| <R0,G0,B0,A0> <R1,G1,B1,A1> <R2,G2,B2,A2> <R3,G3,B3,A3> |
| | | | | | | | | | | | | | | | | |
| | | \__|__ * | * | | | \__|__ * | * | |
| | | | \ | | | | | \ | | |
| | | / | | / | | / | | / |
| V V V V V V V V V V V V |
| <Cb0,Y0,A0> <Cr0,Y1,A1> <Cb2,Y2,A2> <Cr2,Y3,A3> |
| <--- pixel pair ----> <--- pixel pair ----> |
| |
| Figure 4.3: Downsampling with decimation of RGB or RGBA pixels to |
| form subsampled data in host memory. |
| |
| |
| Averaging |
| |
| If the value of PACK_RESAMPLE_OML is RESAMPLE_AVERAGE_OML, then |
| destination component values are defined as: |
| |
| For even pixels: |
| |
| D_i,0 = 3/4 S_i,0 + 1/4 S_i+1,0 i == 0 (first pixel) |
| = 1/4 S_i-1,0 + 3/4 S_i,0 i == <width>-1 (last pixel) |
| = 1/4 S_i-1,0 + otherwise |
| 1/2 S_i,0 + |
| 1/4 S_i+1,0 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i,3 |
| |
| For odd pixels: |
| |
| D_i,0 = 3/4 S_i-1,2 + 1/4 S_i,2 i == <width>-1 (last pixel) |
| = 1/4 S_i-1,2 + otherwise |
| 1/2 S_i,2 + |
| 1/4 S_i+1,2 |
| D_i,1 = S_i,1 |
| D_i,2 = S_i,3 |
| |
| XXX Note that the "last pixel" case is only needed for readbacks where |
| XXX <width> is not even, so may be removable. |
| |
| - Add new figure 4.4 (renumber following figures): |
| |
| FORMAT_SUBSAMPLE_24_24_OML: |
| <R0,G0,B0,A0> <R1,G1,B1,A1> <R2,G2,B2,A2> <R3,G3,B3,A3> |
| | _|_|_______/\_|__|______ | _|__|_______/\_|__|_______ |
| |/ | | | | \|/ | \_______ | | |
| | | \______ _|_/ \______|__|_________ \ _|_/ \______ |
| | | \/ | | | \|/ | |
| V V V V V V V V |
| <Cb0,Y0> <Cr0,Y1> <Cb2,Y2> <Cr2,Y3> |
| |
| FORMAT_SUBSAMPLE_244_244_OML: |
| <R0,G0,B0,A0> <R1,G1,B1,A1> <R2,G2,B2,A2> <R3,G3,B3,A3> |
| | _|_|___|___/\_|__|___|__ | _|__|___|___/\_|__|___|___ |
| |/ | | | | | | \|/ | \___|___ | | | |
| | | \__|___ _|_/ \__|___|__|______|__ \ _|_/ \__|___ |
| | | | \/ | | | | | \|/ | | |
| V V V V V V V V V V V V |
| <Cb0,Y0, A0><Cr0,Y1, A1><Cb2,Y2, A2><Cr2,Y3, A3> |
| |
| Figure 4.4: Downsampling with averaging of RGB or RGBA pixels to |
| form subsampled data in host memory. |
| |
| Additions to Chapter 5 of the OpenGL 1.2.1 Specification (Special Functions) |
| |
| None. |
| |
| Additions to Chapter 6 of the OpenGL 1.2.1 Specification (State and State Requests) |
| |
| None. |
| |
| Additions to the GLX 1.3 Specification |
| |
| None. |
| |
| Errors |
| |
| See above. |
| |
| New State |
| |
| (table 6.17, p. 207) |
| Get Value Type Get Command Initial Value |
| --------- ---- ----------- ------------- |
| UNPACK_RESAMPLE_OML Z3 GetIntegerv RESAMPLE_REPLICATE_OML |
| PACK_RESAMPLE_OML Z2 GetIntegerv RESAMPLE_DECIMATE_OML |
| |
| (continued columns) |
| Get Value Description Sec Attribute |
| --------- ----------- --- --------- |
| UNPACK_RESAMPLE_OML Pixel upsampling mode 3.6 pixel-store |
| PACK_RESAMPLE_OML Pixel downsampling mode 4.3 pixel-store |
| |
| New Implementation Dependent State |
| |
| None. |
| |
| Revision History |
| |
| * Revision 10, 07/24/2001 - Finalized Status for OpenML 1.0. |
| * Revision 9, 07/16/2001 - Remove erroneous redefinition of |
| RESAMPLE_AVERAGE enumerant value. |
| * Revisions 7-8, 07/11/2001 - Assign enum values and extension number |
| for the registry. |
| * Revision 6 - Correct errors in the equations describing subsampling. |
| * Revision 5 - formatting changes for OpenML Specification |
| * Revision 4, 03/27/2001 - Rewrite to use the <format> parameter, |
| rather than a pixel storage mode, to specify subsampled data. |
| * Revision 3 - Removed support for YC component orders. Renamed CY and |
| CYA enumerants more sensibly. Added Discreet's RESAMPLE_AVERAGE |
| resampling mode. Changed text descriptions of sampling to equations. |
| Made enum values undefined until we've determined if this extension |
| is backwards compatible with SGIX_resample. |
| * Revision 2 - corrected 4224 upsampling and downsampling figures. |
| Moved discussion of errors for non-even image widths to the |
| OML_subsample specification. |
| * Revision 1 - derived from SGIX_resample. |
