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[master] Ported bugfix in pngrtran.c from 1.5.3: Ensure coefficients are OK for

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png_rgb_to_gray_fixed().
This commit is contained in:
Glenn Randers-Pehrson
2011-06-05 17:19:17 -05:00
parent c3ac9a507a
commit 0dc882d7c3
3 changed files with 41 additions and 26 deletions
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39
pngrtran.c
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@@ -703,27 +703,38 @@ png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
}
#endif
{
png_uint_16 red_int, green_int;
if (red < 0 || green < 0)
{
red_int = 6968; /* .212671 * 32768 + .5 */
green_int = 23434; /* .715160 * 32768 + .5 */
}
else if (red + green < 100000L)
if (red >= 0 && green >= 0 && red + green <= 100000L)
{
png_uint_16 red_int, green_int;
red_int = (png_uint_16)(((png_uint_32)red*32768L)/100000L);
green_int = (png_uint_16)(((png_uint_32)green*32768L)/100000L);
png_ptr->rgb_to_gray_red_coeff = red_int;
png_ptr->rgb_to_gray_green_coeff = green_int;
png_ptr->rgb_to_gray_blue_coeff =
(png_uint_16)(32768 - red_int - green_int);
}
else
{
png_warning(png_ptr, "ignoring out of range rgb_to_gray coefficients");
red_int = 6968;
green_int = 23434;
if (red >= 0 && green >= 0)
png_warning(png_ptr,
"ignoring out of range rgb_to_gray coefficients");
/* Use the defaults, from the cHRM chunk if set, else the built in Rec
* 709 values (which correspond to sRGB, so we don't have to worry
* about the sRGB chunk!)
*/
if (png_ptr->rgb_to_gray_red_coeff == 0 &&
png_ptr->rgb_to_gray_green_coeff == 0 &&
png_ptr->rgb_to_gray_blue_coeff == 0)
{
png_ptr->rgb_to_gray_red_coeff = 6968; /* .212671 * 32768 + .5 */
png_ptr->rgb_to_gray_green_coeff = 23434; /* .715160 * 32768 + .5 */
png_ptr->rgb_to_gray_blue_coeff = 2366;
}
}
png_ptr->rgb_to_gray_red_coeff = red_int;
png_ptr->rgb_to_gray_green_coeff = green_int;
png_ptr->rgb_to_gray_blue_coeff =
(png_uint_16)(32768 - red_int - green_int);
}
}
#endif