jpeg: use libjpeg-turbo built-in color conversions

modules/imgcodecs/src/grfmt_jpeg.cpp

@@ -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 )
         {
@@ -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 )
@@ -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;
@@ -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 )
                 {
@@ -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;
@@ -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;
@@ -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;
@@ -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) );
@@ -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 );
         }