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| Known bugs and suggested enhancements in libpng-1.0.4 |
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| 1. March 15, 1998 -- OPTIMIZATION -- Kevin Bracey |
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| Loops need to be optimized everywhere |
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| Make them count down instead of up -- Kevin Bracey |
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| Optimizing compilers don't need this, and making |
| the change would be error prone -- Tom Lane, Glenn R-P |
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| Question whether i-- or --i is better. |
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| STATUS: Under investigation, postponed until after |
| libpng-1.0.5. About 160 loops will be turned around |
| in libpng-1.0.Nn, for testing. |
| |
| 2. July 4, 1998 -- ENHANCEMENT -- Glenn R-P |
| |
| libpng-1.0.5 and earlier transform colors to gamma=1.0 space for |
| merging with background, and then back to the image's gamma. The |
| bit_depth of the intermediate (gamma=1.0) representation is probably |
| not sufficient. In the typical gamma=1/2.2 situation, the linear |
| pixels need about 4 more bits than the gamma-encoded ones, to avoid |
| loss of precision. A similar situation exists with the rgb_to_gray |
| operation. |
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| STATUS: under development. |
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| 3. September 1999 -- ENHANCEMENT -- |
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| It should be possible to use libpng without floating-point aritmetic. |
| |
| STATUS: Under investigation, implementation postponed until after |
| libpng-1.0.5. The application interface will change because replacements |
| for the png_set_gAMA(), png_set_cHRM(), and corresponding png_get_() |
| functions will be needed. |
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| 4. September 1999 -- BUG [FIXED] -- |
| |
| Portions of the new MMX code in pngvcrd.c were ifdef'd out because they |
| didn't work properly, but the bug appears to have been found and fixed. |
| As a result, all parts of the code are once again enabled. If you think |
| there's still a problem, you can recompile with one of the following two |
| macros defined and see if the problem goes away: |
| |
| DISABLE_PNGVCRD_COMBINE |
| DISABLE_PNGVCRD_INTERLACE |
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| The second one is in the function where the bug was; as far as we are |
| aware, there was never any bug in the other function. Please notify us |
| if you find any problems in libpng, regardless of whether the two macros |
| make any difference: png-implement@ccrc.wustl.edu |
| |
| Again, we believe the MMX code in pngvcrd.c is 100% correct, but it has |
| not yet been tested extensively. |
