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[libpng15] Fixes for multiple calls to png_read_update_info.

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These fixes attend to most of the errors revealed in pngvalid, however doing
the gamma work twice results in inaccuracies that can't be easily fixed.
There is now a warning in the code if this is going to happen.
This commit is contained in:
John Bowler
2011-10-14 18:19:47 -05:00
committed by Glenn Randers-Pehrson
parent 5c1905caae
commit 07772cba07
10 changed files with 130 additions and 78 deletions
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56
pngrtran.c
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@@ -1641,8 +1641,9 @@ png_init_read_transformations(png_structp png_ptr)
/* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
else /* color_type != PNG_COLOR_TYPE_PALETTE */
{
png_fixed_point g = PNG_FP_1;
png_fixed_point gs = PNG_FP_1;
int gs_sig, g_sig;
png_fixed_point g = PNG_FP_1; /* Correction to linear */
png_fixed_point gs = PNG_FP_1; /* Correction to screen */
switch (png_ptr->background_gamma_type)
{
@@ -1666,34 +1667,45 @@ png_init_read_transformations(png_structp png_ptr)
png_error(png_ptr, "invalid background gamma type");
}
png_ptr->background_1.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, g);
g_sig = png_gamma_significant(g);
gs_sig = png_gamma_significant(gs);
png_ptr->background.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, gs);
if (g_sig)
png_ptr->background_1.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, g);
if (gs_sig)
png_ptr->background.gray = png_gamma_correct(png_ptr,
png_ptr->background.gray, gs);
if ((png_ptr->background.red != png_ptr->background.green) ||
(png_ptr->background.red != png_ptr->background.blue) ||
(png_ptr->background.red != png_ptr->background.gray))
{
/* RGB or RGBA with color background */
png_ptr->background_1.red = png_gamma_correct(png_ptr,
png_ptr->background.red, g);
if (g_sig)
{
png_ptr->background_1.red = png_gamma_correct(png_ptr,
png_ptr->background.red, g);
png_ptr->background_1.green = png_gamma_correct(png_ptr,
png_ptr->background.green, g);
png_ptr->background_1.green = png_gamma_correct(png_ptr,
png_ptr->background.green, g);
png_ptr->background_1.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, g);
png_ptr->background_1.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, g);
}
png_ptr->background.red = png_gamma_correct(png_ptr,
png_ptr->background.red, gs);
if (gs_sig)
{
png_ptr->background.red = png_gamma_correct(png_ptr,
png_ptr->background.red, gs);
png_ptr->background.green = png_gamma_correct(png_ptr,
png_ptr->background.green, gs);
png_ptr->background.green = png_gamma_correct(png_ptr,
png_ptr->background.green, gs);
png_ptr->background.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, gs);
png_ptr->background.blue = png_gamma_correct(png_ptr,
png_ptr->background.blue, gs);
}
}
else
@@ -1705,6 +1717,9 @@ png_init_read_transformations(png_structp png_ptr)
png_ptr->background.red = png_ptr->background.green
= png_ptr->background.blue = png_ptr->background.gray;
}
/* The background is now in screen gamma: */
png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
} /* color_type != PNG_COLOR_TYPE_PALETTE */
}/* png_ptr->transformations & PNG_BACKGROUND */
@@ -3404,7 +3419,8 @@ png_build_grayscale_palette(int bit_depth, png_colorp palette)
#ifdef PNG_READ_TRANSFORMS_SUPPORTED
#ifdef PNG_READ_BACKGROUND_SUPPORTED
#if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
(defined PNG_READ_ALPHA_MODE_SUPPORTED)
/* Replace any alpha or transparency with the supplied background color.
* "background" is already in the screen gamma, while "background_1" is
* at a gamma of 1.0. Paletted files have already been taken care of.
@@ -4112,7 +4128,7 @@ png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
}
}
}
#endif
#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
#ifdef PNG_READ_GAMMA_SUPPORTED
/* Gamma correct the image, avoiding the alpha channel. Make sure