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Merge pull request #6839 from thierrylamarre:better_png_transparency

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This commit is contained in:
Vadim Pisarevsky 2016-07-18 18:24:34 +00:00
commit 1e17ffe9ac
1 changed files with 7 additions and 8 deletions
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15
modules/imgcodecs/src/grfmt_png.cpp
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@ -190,16 +190,14 @@ bool PngDecoder::readHeader()
switch(color_type)
{
case PNG_COLOR_TYPE_RGB:
m_type = CV_8UC3;
break;
case PNG_COLOR_TYPE_PALETTE:
png_get_tRNS( png_ptr, info_ptr, &trans, &num_trans, &trans_values);
//Check if there is a transparency value in the palette
if ( num_trans > 0 )
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, &trans_values);
if( num_trans > 0 )
m_type = CV_8UC4;
else
m_type = CV_8UC3;
break;
case PNG_COLOR_TYPE_GRAY_ALPHA:
case PNG_COLOR_TYPE_RGB_ALPHA:
m_type = CV_8UC4;
break;
@ -255,12 +253,13 @@ bool PngDecoder::readData( Mat& img )
* stripping alpha.. 18.11.2004 Axel Walthelm
*/
png_set_strip_alpha( png_ptr );
}
} else
png_set_tRNS_to_alpha( png_ptr );
if( m_color_type == PNG_COLOR_TYPE_PALETTE )
png_set_palette_to_rgb( png_ptr );
if( m_color_type == PNG_COLOR_TYPE_GRAY && m_bit_depth < 8 )
if( (m_color_type & PNG_COLOR_MASK_COLOR) == 0 && m_bit_depth < 8 )
#if (PNG_LIBPNG_VER_MAJOR*10000 + PNG_LIBPNG_VER_MINOR*100 + PNG_LIBPNG_VER_RELEASE >= 10209) || \
(PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR == 0 && PNG_LIBPNG_VER_RELEASE >= 18)
png_set_expand_gray_1_2_4_to_8( png_ptr );
@ -268,7 +267,7 @@ bool PngDecoder::readData( Mat& img )
png_set_gray_1_2_4_to_8( png_ptr );
#endif
if( CV_MAT_CN(m_type) > 1 && color )
if( (m_color_type & PNG_COLOR_MASK_COLOR) && color )
png_set_bgr( png_ptr ); // convert RGB to BGR
else if( color )
png_set_gray_to_rgb( png_ptr ); // Gray->RGB