Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 1 | |
Glenn Randers-Pehrson | 4393a9a | 1999-09-17 12:27:26 -0500 | [diff] [blame] | 2 | Known bugs and suggested enhancements in libpng-1.0.4 |
Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 3 | |
Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 4 | |
Glenn Randers-Pehrson | 345bc27 | 1998-06-14 14:43:31 -0500 | [diff] [blame] | 5 | 1. March 15, 1998 -- OPTIMIZATION -- Kevin Bracey |
Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 6 | |
| 7 | Loops need to be optimized everywhere |
| 8 | |
Glenn Randers-Pehrson | 345bc27 | 1998-06-14 14:43:31 -0500 | [diff] [blame] | 9 | Make them count down instead of up -- Kevin Bracey |
Glenn Randers-Pehrson | 5c6aeb2 | 1998-12-29 11:47:59 -0600 | [diff] [blame] | 10 | |
Glenn Randers-Pehrson | 345bc27 | 1998-06-14 14:43:31 -0500 | [diff] [blame] | 11 | Optimizing compilers don't need this, and making |
| 12 | the change would be error prone -- Tom Lane, Glenn R-P |
Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 13 | |
Glenn Randers-Pehrson | 345bc27 | 1998-06-14 14:43:31 -0500 | [diff] [blame] | 14 | Question whether i-- or --i is better. |
Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 15 | |
Glenn Randers-Pehrson | 345bc27 | 1998-06-14 14:43:31 -0500 | [diff] [blame] | 16 | STATUS: Under investigation, postponed until after |
Glenn Randers-Pehrson | 4393a9a | 1999-09-17 12:27:26 -0500 | [diff] [blame] | 17 | libpng-1.0.4. About 160 loops will be turned around |
Glenn Randers-Pehrson | 5c6aeb2 | 1998-12-29 11:47:59 -0600 | [diff] [blame] | 18 | in libpng-1.0.Nn, for testing. |
| 19 | |
Glenn Randers-Pehrson | 87544ac | 1999-01-13 22:06:39 -0600 | [diff] [blame] | 20 | 2. July 4, 1998 -- ENHANCEMENT -- Glenn R-P |
Glenn Randers-Pehrson | 5c6aeb2 | 1998-12-29 11:47:59 -0600 | [diff] [blame] | 21 | |
Glenn Randers-Pehrson | 4393a9a | 1999-09-17 12:27:26 -0500 | [diff] [blame] | 22 | libpng-1.0.4 and earlier transform colors to gamma=1.0 space for |
Glenn Randers-Pehrson | 5c6aeb2 | 1998-12-29 11:47:59 -0600 | [diff] [blame] | 23 | merging with background, and then back to the image's gamma. The |
| 24 | bit_depth of the intermediate (gamma=1.0) representation is probably |
| 25 | not sufficient. In the typical gamma=1/2.2 situation, the linear |
| 26 | pixels need about 4 more bits than the gamma-encoded ones, to avoid |
| 27 | loss of precision. A similar situation exists with the rgb_to_gray |
| 28 | operation. |
| 29 | |
| 30 | STATUS: under development. |
| 31 | |
Glenn Randers-Pehrson | 4393a9a | 1999-09-17 12:27:26 -0500 | [diff] [blame] | 32 | 3. September 1999 -- ENHANCEMENT -- |
| 33 | |
| 34 | It should be possible to use libpng without floating-point aritmetic. |
| 35 | |
| 36 | STATUS: Under investigation, implementation postponed until after |
| 37 | libpng-1.0.4. The application interface will change because replacements |
| 38 | for the png_set_gAMA(), png_set_cHRM(), and corresponding png_get_() |
| 39 | functions will be needed. |
Glenn Randers-Pehrson | 896239b | 1998-04-21 15:03:57 -0500 | [diff] [blame] | 40 | |