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jpeg: use libjpeg-turbo built-in color conversions #24875

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Merged
merged 1 commit into from
Jan 23, 2024
Merged

jpeg: use libjpeg-turbo built-in color conversions #24875

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35 changes: 35 additions & 0 deletions modules/imgcodecs/src/grfmt_jpeg.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -409,7 +409,9 @@ bool JpegDecoder::readData( Mat& img )
{
jpeg_decompress_struct* cinfo = &((JpegState*)m_state)->cinfo;
JpegErrorMgr* jerr = &((JpegState*)m_state)->jerr;
#ifndef JCS_EXTENSIONS
JSAMPARRAY buffer = 0;
#endif

if( setjmp( jerr->setjmp_buffer ) == 0 )
{
Expand All @@ -429,6 +431,18 @@ bool JpegDecoder::readData( Mat& img )
}
#endif

#ifdef JCS_EXTENSIONS
if( color )
{
cinfo->out_color_space = JCS_EXT_BGR;
cinfo->out_color_components = 3;
}
else
{
cinfo->out_color_space = JCS_GRAYSCALE;
cinfo->out_color_components = 1;
}
#else
if( color )
{
if( cinfo->num_components != 4 )
Expand All @@ -455,6 +469,7 @@ bool JpegDecoder::readData( Mat& img )
cinfo->out_color_components = 4;
}
}
#endif

// Check for Exif marker APP1
jpeg_saved_marker_ptr exif_marker = NULL;
Expand All @@ -481,12 +496,17 @@ bool JpegDecoder::readData( Mat& img )

jpeg_start_decompress( cinfo );

#ifndef JCS_EXTENSIONS
buffer = (*cinfo->mem->alloc_sarray)((j_common_ptr)cinfo,
JPOOL_IMAGE, m_width*4, 1 );
#endif

uchar* data = img.ptr();
for( ; m_height--; data += step )
{
#ifdef JCS_EXTENSIONS
jpeg_read_scanlines( cinfo, &data, 1 );
#else
jpeg_read_scanlines( cinfo, buffer, 1 );
if( color )
{
Expand All @@ -502,6 +522,7 @@ bool JpegDecoder::readData( Mat& img )
else
icvCvt_CMYK2Gray_8u_C4C1R( buffer[0], 0, data, 0, Size(m_width,1) );
}
#endif
}

result = true;
Expand Down Expand Up @@ -593,8 +614,11 @@ bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )
int width = img.cols, height = img.rows;

std::vector<uchar> out_buf(1 << 12);

#ifndef JCS_EXTENSIONS
AutoBuffer<uchar> _buffer;
uchar* buffer;
#endif

struct jpeg_compress_struct cinfo;
JpegErrorMgr jerr;
Expand Down Expand Up @@ -629,8 +653,15 @@ bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )

int _channels = img.channels();
int channels = _channels > 1 ? 3 : 1;

#ifdef JCS_EXTENSIONS
cinfo.input_components = _channels;
cinfo.in_color_space = _channels == 3 ? JCS_EXT_BGR
: _channels == 4 ? JCS_EXT_BGRX : JCS_GRAYSCALE;
#else
cinfo.input_components = channels;
cinfo.in_color_space = channels > 1 ? JCS_RGB : JCS_GRAYSCALE;
#endif

int quality = 95;
int progressive = 0;
Expand Down Expand Up @@ -746,14 +777,17 @@ bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )

jpeg_start_compress( &cinfo, TRUE );

#ifndef JCS_EXTENSIONS
if( channels > 1 )
_buffer.allocate(width*channels);
buffer = _buffer.data();
#endif

for( int y = 0; y < height; y++ )
{
uchar *data = img.data + img.step*y, *ptr = data;

#ifndef JCS_EXTENSIONS
if( _channels == 3 )
{
icvCvt_BGR2RGB_8u_C3R( data, 0, buffer, 0, Size(width,1) );
Expand All @@ -764,6 +798,7 @@ bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )
icvCvt_BGRA2BGR_8u_C4C3R( data, 0, buffer, 0, Size(width,1), 2 );
ptr = buffer;
}
#endif

jpeg_write_scanlines( &cinfo, &ptr, 1 );
}
Expand Down