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Fix debug test of output gamma

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The test would fire when a gamma transform was eliminated because it was not
significant if other transforms remained.  This is a debug-only change to alter
the test to check for an insignificant mis-match of the actual output gamma from
the requested output gamma.

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler 2016-07-23 10:03:48 -07:00
parent 8ffea2e56b
commit 4283e2bf66
3 changed files with 32 additions and 3 deletions
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8
pngpriv.h
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@ -2117,6 +2117,14 @@ PNG_INTERNAL_FUNCTION(unsigned int,png_gamma_nxmbit_correct,
/* In this case the value must have 'n' bits and the output will have 'm'
* bits.
*/
#if !PNG_RELEASE_BUILD
PNG_INTERNAL_FUNCTION(int,png_gamma_check,(png_const_structrp png_ptr,
png_const_transform_controlp tc),PNG_EMPTY);
/* Debugging only routine to repeat the test used above to determine if the
* gamma was insignificant.
*/
#endif /* !RELEASE_BUILD */
#endif /* READ_GAMMA */
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED

20
pngrtran.c
View File

@ -3434,6 +3434,26 @@ png_init_gamma(png_transformp *transform, png_transform_controlp tc)
}
}
#if !PNG_RELEASE_BUILD
int /* PRIVATE(debug only) */
png_gamma_check(png_const_structrp png_ptr, png_const_transform_controlp tc)
/* Debugging only routine to repeat the test used above to determine if the
* gamma was insignificant.
*
* NOTE: JB20160723: This may still be incorrect in a complicated transform
* pipeline because it uses 'tc_sBIT' for the end of the pipeline whereas the
* init above happens earlier. I don't think this matters because the test
* is only invoked if the gamma transform is eliminated or if there is a bug
* and in the former case the sBIT values should remain unchanged.
*/
{
png_fixed_point dummy;
return png_gamma_equal(png_ptr, png_ptr->row_gamma, tc->gamma, &dummy,
tc_sBIT(tc));
}
#endif /* !RELEASE_BUILD */
static png_fixed_point
translate_gamma_flags(png_const_structrp png_ptr, png_fixed_point gamma,
int is_screen)

7
pngrutil.c
View File

@ -4309,10 +4309,11 @@ png_read_process_IDAT(png_structrp png_ptr, png_bytep transformed_row,
png_ptr->row_range == tc.range &&
png_ptr->row_bit_depth == tc.bit_depth);
# ifdef PNG_READ_GAMMA_SUPPORTED
/* This sometimes fails at present when gamma
* transforms are eliminated in PNG_TC_INIT_FINAL:
/* This checks the output gamma taking into account the
* fact that small gamma changes are eliminated.
*/
debug(png_ptr->row_gamma == tc.gamma);
debug(png_ptr->row_gamma == tc.gamma ||
png_gamma_check(png_ptr, &tc));
# endif /* READ_GAMMA */
/* If the caller needs the row saved (for the progressive