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[devel] Reversed earlier change of transformation order; move

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png_expand_16 back where it was before libpng-1.5.3beta07.
The change doesn't work because it requires 16 bit gamma tables when the code
only generates 8 bit ones.  This fails silently; the libpng code just doesn't
do any gamma correction.  Moving the tests back leaves the old, inaccurate, 8
bit gamma calculations, but these are clearly better than none!
This commit is contained in:
John Bowler
2011-05-16 20:57:54 -05:00
committed by Glenn Randers-Pehrson
parent bb4f77cd95
commit 1921e6db90
4 changed files with 59 additions and 39 deletions
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37
pngrtran.c
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@@ -1318,7 +1318,7 @@ png_init_read_transformations(png_structp png_ptr)
* 8) PNG_ENCODE_ALPHA
* 9) PNG_16_TO_8 (strip16)
* 10) PNG_QUANTIZE (converts to palette)
* 11) PNG_EXPAND_16 [NOTE: temporarily moved to (3) for accuracy!]
* 11) PNG_EXPAND_16
* 12) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
* 13) PNG_INVERT_MONO
* 14) PNG_SHIFT
@@ -1808,14 +1808,6 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
}
#endif
#ifdef PNG_READ_EXPAND_16_SUPPORTED
if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
info_ptr->bit_depth = 16;
}
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
defined(PNG_READ_ALPHA_MODE_SUPPORTED)
/* The following is almost certainly wrong unless the background value is in
@@ -1870,6 +1862,14 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
}
#endif
#ifdef PNG_READ_EXPAND_16_SUPPORTED
if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
{
info_ptr->bit_depth = 16;
}
#endif
#ifdef PNG_READ_PACK_SUPPORTED
if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
info_ptr->bit_depth = 8;
@@ -1995,19 +1995,6 @@ png_do_read_transformations(png_structp png_ptr)
}
#endif
/* TODO: Delay the 'expand 16' step until later for efficiency, so that the
* intermediate steps work with 8 bit data.
*/
#ifdef PNG_READ_EXPAND_16_SUPPORTED
/* Do the expansion now, after all the arithmetic has been done. Notice
* that previous transformations can handle the PNG_EXPAND_16 flag if this
* is efficient (particularly true in the case of gamma correction, where
* better accuracy results faster!)
*/
if (png_ptr->transformations & PNG_EXPAND_16)
png_do_expand_16(&png_ptr->row_info, png_ptr->row_buf + 1);
#endif
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
!(png_ptr->transformations & PNG_COMPOSE) &&
@@ -2127,11 +2114,6 @@ png_do_read_transformations(png_structp png_ptr)
}
#endif /* PNG_READ_QUANTIZE_SUPPORTED */
#if 0
/* This is where this code *should* be for efficiency, but that requires all
* the inaccurate calculations above to output 16 bit values if expand_16 is
* set!
*/
#ifdef PNG_READ_EXPAND_16_SUPPORTED
/* Do the expansion now, after all the arithmetic has been done. Notice
* that previous transformations can handle the PNG_EXPAND_16 flag if this
@@ -2141,7 +2123,6 @@ png_do_read_transformations(png_structp png_ptr)
if (png_ptr->transformations & PNG_EXPAND_16)
png_do_expand_16(&png_ptr->row_info, png_ptr->row_buf + 1);
#endif
#endif /*commented out*/
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/*NOTE: moved here in 1.5.3 (from much later in this list.) */