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sBIT code coverage and fixes

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Fixes for sBIT handling in the low-bit-depth gray and pngstest cases, extends
sBIT handling to the colormap code in the simplified API which is separately
implemented in pngread.c

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler
2015-09-26 15:24:20 -07:00
parent 8dfa93beed
commit 23324b8559
7 changed files with 295 additions and 102 deletions
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45
pngrtran.c
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@@ -882,10 +882,7 @@ png_do_expand_lbd_gray(png_transformp *transform, png_transform_controlp tc)
if (bit_depth > 1U /* irrelevant for bit depth 1 */ &&
!(tc->invalid_info & PNG_INFO_sBIT) &&
tc->sBIT_G > 0U/*SAFETY*/ && tc->sBIT_G < bit_depth)
{
insignificant_bits = bit_depth - tc->sBIT_G;
UNTESTED
}
# endif /* READ_sBIT */
# ifdef PNG_READ_tRNS_SUPPORTED
@@ -949,10 +946,7 @@ png_do_expand_lbd_gray(png_transformp *transform, png_transform_controlp tc)
* of 1 bit gray + 1 bit alpha (transparency):
*/
if (insignificant_bits /* only 1 bit significant */)
{
*--dp = PNG_BYTE((pixel >> 1) * 255U);
UNTESTED
}
else
# endif
@@ -990,10 +984,7 @@ png_do_expand_lbd_gray(png_transformp *transform, png_transform_controlp tc)
* below.
*/
if (insignificant_bits)
{
pixel = ((pixel>>insignificant_bits) * 255U + (div>>1)) / div;
UNTESTED
}
else
# endif
@@ -2142,10 +2133,10 @@ png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
}
#endif /* UNUSED */
/* libpng-1.7.0: this internal function converts an n-bit input value to an
/* libpng-1.7.0: this private function converts an n-bit input value to an
* m-bit output value.
*/
static unsigned int
unsigned int
png_gamma_nxmbit_correct(unsigned int value, png_fixed_point gamma_val,
unsigned int n/*input bits*/, unsigned int m/*output bits */)
{
@@ -2186,21 +2177,6 @@ png_gamma_nxmbit_correct(unsigned int value, png_fixed_point gamma_val,
}
}
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
png_uint_16
png_gamma_16bit_correct(png_const_structrp png_ptr, unsigned int value,
png_fixed_point gamma_val)
{
/* This is a hook into this code for use by the simplified API (only) */
return png_check_u16(png_ptr,
png_gamma_nxmbit_correct(value, gamma_val, 16U, 16U));
PNG_UNUSED(png_ptr)
}
#endif /* SIMPLIFIED_READ */
#undef png_gamma_16bit_correct /* circumvent the prefix handling */
#define png_gamma_16bit_correct NOT_USED_HERE /* for checking */
#if 0 /*UNUSED*/
static unsigned int
png_gamma_sbit_correct(unsigned int value, png_fixed_point gamma_val,
@@ -4899,9 +4875,12 @@ png_do_background_alpha_GA(png_transformp *transform, png_transform_controlp tc)
const int compose = tr->st.compose_background;
affirm(tc->bit_depth == 16U && tc->format == PNG_FORMAT_GA &&
tr->st.background_bit_depth == 16U &&
(tr->st.background_gamma == tc->gamma ||
tr->st.background_gamma == 0));
tr->st.background_bit_depth == 16U);
/* If gamma transforms are eliminated this might fail: */
debug(tr->st.background_gamma == tc->gamma ||
tr->st.background_gamma == 0 ||
tc->sBIT_G == 1);
tc->sp = tc->dp; /* nothing else changes */
@@ -4968,9 +4947,11 @@ png_do_background_alpha_RGBA(png_transformp *transform,
const int compose = tr->st.compose_background;
affirm(tc->bit_depth == 16U && tc->format == PNG_FORMAT_RGBA &&
tr->st.background_bit_depth == 16U &&
(tr->st.background_gamma == tc->gamma ||
tr->st.background_gamma == 0));
tr->st.background_bit_depth == 16U);
debug(tr->st.background_gamma == tc->gamma ||
tr->st.background_gamma == 0 ||
(tc->sBIT_R == 1 && tc->sBIT_G == 1 && tc->sBIT_B == 1));
tc->sp = tc->dp; /* nothing else changes */