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[libpng15] Fix PNG_SIMPLIFIED transformations,

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adding alpha and reducing to 8-bit
This commit is contained in:
John Bowler 2011-11-08 10:38:09 -06:00 committed by Glenn Randers-Pehrson
parent e0a6c06bfd
commit 3615d03e05
2 changed files with 39 additions and 19 deletions
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55
pngread.c
View File

@ -1708,12 +1708,13 @@ png_image_read_end(png_voidp argument)
{ {
png_uint_32 base_format = png_image_format(png_ptr, info_ptr); png_uint_32 base_format = png_image_format(png_ptr, info_ptr);
png_uint_32 change = format ^ base_format; png_uint_32 change = format ^ base_format;
png_fixed_point output_gamma;
int mode; /* alpha mode */
/* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
*/ */
{ {
png_fixed_point input_gamma_default, output_gamma; png_fixed_point input_gamma_default;
int mode;
if (base_format & PNG_FORMAT_FLAG_LINEAR) if (base_format & PNG_FORMAT_FLAG_LINEAR)
input_gamma_default = PNG_GAMMA_LINEAR; input_gamma_default = PNG_GAMMA_LINEAR;
@ -1722,7 +1723,7 @@ png_image_read_end(png_voidp argument)
if (linear) if (linear)
{ {
mode = PNG_ALPHA_STANDARD; mode = PNG_ALPHA_STANDARD; /* associated alpha */
output_gamma = PNG_GAMMA_LINEAR; output_gamma = PNG_GAMMA_LINEAR;
} }
@ -1732,24 +1733,25 @@ png_image_read_end(png_voidp argument)
output_gamma = PNG_DEFAULT_sRGB; output_gamma = PNG_DEFAULT_sRGB;
} }
/* Set the mode, the default gamma for the file and then, if it /* If the input default and output gamma do not match, because sRGB is
* doesn't match the default, the output gamma. * being changed to linear, set the input default now via a dummy call
* to png_set_alpha_mode_fixed.
*/ */
png_set_alpha_mode_fixed(png_ptr, mode, input_gamma_default);
if (input_gamma_default != output_gamma) if (input_gamma_default != output_gamma)
png_set_alpha_mode(png_ptr, mode, output_gamma); png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG,
input_gamma_default);
}
/* If the bit-depth changes then handle that here. */ /* If the bit-depth changes then handle that here. */
if (change & PNG_FORMAT_FLAG_LINEAR) if (change & PNG_FORMAT_FLAG_LINEAR)
{ {
if (linear /*16-bit output*/) if (linear /*16-bit output*/)
png_set_expand_16(png_ptr); png_set_expand_16(png_ptr);
else /* 8-bit output */ else /* 8-bit output */
png_set_scale_16(png_ptr); png_set_scale_16(png_ptr);
change &= ~PNG_FORMAT_FLAG_LINEAR; change &= ~PNG_FORMAT_FLAG_LINEAR;
}
} }
/* Now the background/alpha channel changes. */ /* Now the background/alpha channel changes. */
@ -1761,9 +1763,11 @@ png_image_read_end(png_voidp argument)
*/ */
if (base_format & PNG_FORMAT_FLAG_ALPHA) if (base_format & PNG_FORMAT_FLAG_ALPHA)
{ {
/* 16-bit output: just remove the channel */
if (linear) /* compose on black (well, pre-multiply) */ if (linear) /* compose on black (well, pre-multiply) */
png_set_strip_alpha(png_ptr); png_set_strip_alpha(png_ptr);
/* 8-bit output: do an appropriate compose */
else if (display->background != NULL) else if (display->background != NULL)
{ {
png_color_16 c; png_color_16 c;
@ -1793,8 +1797,7 @@ png_image_read_end(png_voidp argument)
* one so the code only has to hack on the pixels that require * one so the code only has to hack on the pixels that require
* composition. * composition.
*/ */
png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED, mode = PNG_ALPHA_OPTIMIZED;
PNG_DEFAULT_sRGB);
} }
} }
@ -1804,12 +1807,26 @@ png_image_read_end(png_voidp argument)
* been accomplished, so always add the alpha channel after the * been accomplished, so always add the alpha channel after the
* component channels. * component channels.
*/ */
png_set_add_alpha(png_ptr, 255/*opaque*/, PNG_FILLER_AFTER); png_uint_32 filler; /* opaque filler */
if (linear)
filler = 65535;
else
filler = 255;
png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
} }
change &= ~PNG_FORMAT_FLAG_ALPHA; change &= ~PNG_FORMAT_FLAG_ALPHA;
} }
/* Now set the alpha mode correctly; this is always done, even if there is
* no alpha channel in either the input or the output because it correctly
* sets the output gamma.
*/
png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
if (change & PNG_FORMAT_FLAG_COLOR) if (change & PNG_FORMAT_FLAG_COLOR)
{ {
/* gray<->color transformation required. */ /* gray<->color transformation required. */

3
pngwrite.c
View File

@ -1910,6 +1910,9 @@ png_write_image_8bit(png_voidp argument)
++in_ptr; ++in_ptr;
++out_ptr; ++out_ptr;
} /* while out_ptr < row_end */ } /* while out_ptr < row_end */
png_write_row(png_ptr, output_row);
input_row += display->row_bytes/(sizeof (png_uint_16));
} /* while y */ } /* while y */
} }