From 1a73305ac2e0c121c9db43f557673735ecc7e962 Mon Sep 17 00:00:00 2001 From: Glenn Randers-Pehrson Date: Mon, 13 Jul 2015 14:53:27 -0500 Subject: [PATCH] [libpng16] Removed WEIGHTED_FILTER info from the man page. --- libpng-manual.txt | 35 ----------------------------------- libpng.3 | 35 ----------------------------------- 2 files changed, 70 deletions(-) diff --git a/libpng-manual.txt b/libpng-manual.txt index 89c36e73b..5ba3e0674 100644 --- a/libpng-manual.txt +++ b/libpng-manual.txt @@ -4357,41 +4357,6 @@ is called for the first time.) same as the value of filter_method used in png_set_IHDR(). -It is also possible to influence how libpng chooses from among the -available filters. This is done in one or both of two ways - by -telling it how important it is to keep the same filter for successive -rows, and by telling it the relative computational costs of the filters. - - double weights[3] = {1.5, 1.3, 1.1}, - costs[PNG_FILTER_VALUE_LAST] = - {1.0, 1.3, 1.3, 1.5, 1.7}; - - png_set_filter_heuristics(png_ptr, - PNG_FILTER_HEURISTIC_WEIGHTED, 3, - weights, costs); - -The weights are multiplying factors that indicate to libpng that the -row filter should be the same for successive rows unless another row filter -is that many times better than the previous filter. In the above example, -if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a -"sum of absolute differences" 1.5 x 1.3 times higher than other filters -and still be chosen, while the NONE filter could have a sum 1.1 times -higher than other filters and still be chosen. Unspecified weights are -taken to be 1.0, and the specified weights should probably be declining -like those above in order to emphasize recent filters over older filters. - -The filter costs specify for each filter type a relative decoding cost -to be considered when selecting row filters. This means that filters -with higher costs are less likely to be chosen over filters with lower -costs, unless their "sum of absolute differences" is that much smaller. -The costs do not necessarily reflect the exact computational speeds of -the various filters, since this would unduly influence the final image -size. - -Note that the numbers above were invented purely for this example and -are given only to help explain the function usage. Little testing has -been done to find optimum values for either the costs or the weights. - Requesting debug printout The macro definition PNG_DEBUG can be used to request debugging diff --git a/libpng.3 b/libpng.3 index c219edafa..48d283bc9 100644 --- a/libpng.3 +++ b/libpng.3 @@ -4861,41 +4861,6 @@ is called for the first time.) same as the value of filter_method used in png_set_IHDR(). -It is also possible to influence how libpng chooses from among the -available filters. This is done in one or both of two ways - by -telling it how important it is to keep the same filter for successive -rows, and by telling it the relative computational costs of the filters. - - double weights[3] = {1.5, 1.3, 1.1}, - costs[PNG_FILTER_VALUE_LAST] = - {1.0, 1.3, 1.3, 1.5, 1.7}; - - png_set_filter_heuristics(png_ptr, - PNG_FILTER_HEURISTIC_WEIGHTED, 3, - weights, costs); - -The weights are multiplying factors that indicate to libpng that the -row filter should be the same for successive rows unless another row filter -is that many times better than the previous filter. In the above example, -if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a -"sum of absolute differences" 1.5 x 1.3 times higher than other filters -and still be chosen, while the NONE filter could have a sum 1.1 times -higher than other filters and still be chosen. Unspecified weights are -taken to be 1.0, and the specified weights should probably be declining -like those above in order to emphasize recent filters over older filters. - -The filter costs specify for each filter type a relative decoding cost -to be considered when selecting row filters. This means that filters -with higher costs are less likely to be chosen over filters with lower -costs, unless their "sum of absolute differences" is that much smaller. -The costs do not necessarily reflect the exact computational speeds of -the various filters, since this would unduly influence the final image -size. - -Note that the numbers above were invented purely for this example and -are given only to help explain the function usage. Little testing has -been done to find optimum values for either the costs or the weights. - .SS Requesting debug printout The macro definition PNG_DEBUG can be used to request debugging