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Imported from libpng-0.99p.tar

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This commit is contained in:
Glenn Randers-Pehrson
1998-03-08 22:55:17 -06:00
parent 38d73aff67
commit 4922b1b6e9
31 changed files with 196 additions and 122 deletions
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85
pngrtran.c
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@@ -1,12 +1,12 @@
/* pngrtran.c - transforms the data in a row for PNG readers
*
* libpng 1.00
* libpng 1.0.1
* For conditions of distribution and use, see copyright notice in png.h
* Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
* Copyright (c) 1996, 1997 Andreas Dilger
* Copyright (c) 1998, Glenn Randers-Pehrson
* March 7, 1998
* March 9, 1998
*
* This file contains functions optionally called by an application
* in order to tell libpng how to handle data when reading a PNG.
@@ -665,7 +665,8 @@ png_init_read_transformations(png_structp png_ptr)
if (png_ptr->transformations & PNG_INVERT_ALPHA)
{
#if defined(PNG_READ_EXPAND_SUPPORTED)
if (png_ptr->transformations & !PNG_EXPAND)
/* GRR BUG #1: was (png_ptr->transformations & !PNG_EXPAND) */
if (!(png_ptr->transformations & PNG_EXPAND))
#endif
{
/* invert the alpha channel (in tRNS) unless the pixels are
@@ -712,41 +713,65 @@ png_init_read_transformations(png_structp png_ptr)
}
else
{
double g;
double g, gs;
g = 1.0 / (png_ptr->background_gamma * png_ptr->screen_gamma);
if (png_ptr->background_gamma_type==PNG_BACKGROUND_GAMMA_SCREEN||
fabs(g - 1.0) < PNG_GAMMA_THRESHOLD)
/*
GRR BUG #3: inconsistent with handling of full RGBA below
g = 1.0 / png_ptr->background_gamma;
gs = 1.0 / (png_ptr->background_gamma * png_ptr->screen_gamma);
*/
switch (png_ptr->background_gamma_type)
{
back.red = (png_byte)png_ptr->background.red;
case PNG_BACKGROUND_GAMMA_SCREEN:
g = (png_ptr->screen_gamma);
gs = 1.0;
break;
case PNG_BACKGROUND_GAMMA_FILE:
g = 1.0 / (png_ptr->gamma);
gs = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
break;
case PNG_BACKGROUND_GAMMA_UNIQUE:
g = 1.0 / (png_ptr->background_gamma);
gs = 1.0 / (png_ptr->background_gamma *
png_ptr->screen_gamma);
break;
default:
g = 1.0; /* back_1 */
gs = 1.0; /* back */
}
if (
/*
GRR BUG #2: This creates self-inconsistent images--fully
transparent and fully opaque look fine, but translucent
pixels are wrong (too bright if XV's code can be trusted).
Commenting it out makes an internally self-consistent
image, but still not consistent with RGBA version of same
thing (again, too bright in XV).
png_ptr->background_gamma_type==PNG_BACKGROUND_GAMMA_SCREEN||
*/
fabs(gs - 1.0) < PNG_GAMMA_THRESHOLD)
{
back.red = (png_byte)png_ptr->background.red;
back.green = (png_byte)png_ptr->background.green;
back.blue = (png_byte)png_ptr->background.blue;
back.blue = (png_byte)png_ptr->background.blue;
}
else
{
back.red =
(png_byte)(pow((double)png_ptr->background.red/255, g) *
255.0 + 0.5);
back.green =
(png_byte)(pow((double)png_ptr->background.green/255, g) *
255.0 + 0.5);
back.blue =
(png_byte)(pow((double)png_ptr->background.blue/255, g) *
255.0 + 0.5);
back.red = (png_byte)(pow(
(double)png_ptr->background.red/255, gs) * 255.0 + .5);
back.green = (png_byte)(pow(
(double)png_ptr->background.green/255, gs) * 255.0 + .5);
back.blue = (png_byte)(pow(
(double)png_ptr->background.blue/255, gs) * 255.0 + .5);
}
g = 1.0 / png_ptr->background_gamma;
back_1.red =
(png_byte)(pow((double)png_ptr->background.red/255, g) *
255.0 + 0.5);
back_1.green =
(png_byte)(pow((double)png_ptr->background.green/255, g) *
255.0 + 0.5);
back_1.blue =
(png_byte)(pow((double)png_ptr->background.blue/255, g) *
255.0 + 0.5);
back_1.red = (png_byte)(pow(
(double)png_ptr->background.red/255, g) * 255.0 + .5);
back_1.green = (png_byte)(pow(
(double)png_ptr->background.green/255, g) * 255.0 + .5);
back_1.blue = (png_byte)(pow(
(double)png_ptr->background.blue/255, g) * 255.0 + .5);
}
for (i = 0; i < num_palette; i++)