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preserve alpha channel in PNG, when imread(..., -1) is called (ticket #1107)

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This commit is contained in:
Vadim Pisarevsky 2011-08-11 22:38:09 +00:00
parent 6942799669
commit c65c67eff4
1 changed files with 24 additions and 12 deletions
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18
modules/highgui/src/grfmt_png.cpp
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@ -167,9 +167,18 @@ bool PngDecoder::readHeader()
if( bit_depth <= 8 || bit_depth == 16 ) if( bit_depth <= 8 || bit_depth == 16 )
{ {
m_type = color_type == PNG_COLOR_TYPE_RGB || switch(color_type)
color_type == PNG_COLOR_TYPE_RGB_ALPHA || {
color_type == PNG_COLOR_TYPE_PALETTE ? CV_8UC3 : CV_8UC1; case PNG_COLOR_TYPE_RGB:
case PNG_COLOR_TYPE_PALETTE:
m_type = CV_8UC3;
break;
case PNG_COLOR_TYPE_RGB_ALPHA:
m_type = CV_8UC4;
break;
default:
m_type = CV_8UC1;
}
if( bit_depth == 16 ) if( bit_depth == 16 )
m_type = CV_MAKETYPE(CV_16U, CV_MAT_CN(m_type)); m_type = CV_MAKETYPE(CV_16U, CV_MAT_CN(m_type));
result = true; result = true;
@ -210,6 +219,8 @@ bool PngDecoder::readData( Mat& img )
else if( !isBigEndian() ) else if( !isBigEndian() )
png_set_swap( png_ptr ); png_set_swap( png_ptr );
if(img.channels() < 4)
{
/* observation: png_read_image() writes 400 bytes beyond /* observation: png_read_image() writes 400 bytes beyond
* end of data when reading a 400x118 color png * end of data when reading a 400x118 color png
* "mpplus_sand.png". OpenCV crashes even with demo * "mpplus_sand.png". OpenCV crashes even with demo
@ -219,6 +230,7 @@ bool PngDecoder::readData( Mat& img )
* stripping alpha.. 18.11.2004 Axel Walthelm * stripping alpha.. 18.11.2004 Axel Walthelm
*/ */
png_set_strip_alpha( png_ptr ); png_set_strip_alpha( png_ptr );
}
if( m_color_type == PNG_COLOR_TYPE_PALETTE ) if( m_color_type == PNG_COLOR_TYPE_PALETTE )
png_set_palette_to_rgb( png_ptr ); png_set_palette_to_rgb( png_ptr );