set_quality_ratings (j_compress_ptr cinfo, char *arg, boolean force_baseline)
/* Process a quality-ratings parameter string, of the form
* N[,N,...]
* If there are more q-table slots than parameters, the last value is replicated.
*/
{
int val = 75; /* default value */
int tblno;
char ch;
for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
if (*arg) {
ch = ','; /* if not set by sscanf, will be ',' */
if (sscanf(arg, "%d%c", &val, &ch) < 1)
return FALSE;
if (ch != ',') /* syntax check */
return FALSE;
/* Convert user 0-100 rating to percentage scaling */
cinfo->q_scale_factor[tblno] = jpeg_quality_scaling(val);
while (*arg && *arg++ != ',') /* advance to next segment of arg string */
;
} else {
/* reached end of parameter, set remaining factors to last value */
cinfo->q_scale_factor[tblno] = jpeg_quality_scaling(val);
}
}
jpeg_default_qtables(cinfo, force_baseline);
return TRUE;
}
bool JpegEncoder::write( const Mat& img, const std::vector<int>& params )
{
m_last_error.clear();
struct fileWrapper
{
FILE* f;
fileWrapper() : f(0) {}
~fileWrapper() { if(f) fclose(f); }
};
volatile bool result = false;
fileWrapper fw;
int width = img.cols, height = img.rows;
std::vector<uchar> out_buf(1 << 12);
AutoBuffer<uchar> _buffer;
uchar* buffer;
struct jpeg_compress_struct cinfo;
JpegErrorMgr jerr;
JpegDestination dest;
jpeg_create_compress(&cinfo);
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = error_exit;
if( !m_buf )
{
fw.f = fopen( m_filename.c_str(), "wb" );
if( !fw.f )
goto _exit_;
jpeg_stdio_dest( &cinfo, fw.f );
}
else
{
dest.dst = m_buf;
dest.buf = &out_buf;
jpeg_buffer_dest( &cinfo, &dest );
dest.pub.next_output_byte = &out_buf[0];
dest.pub.free_in_buffer = out_buf.size();
}
if( setjmp( jerr.setjmp_buffer ) == 0 )
{
cinfo.image_width = width;
cinfo.image_height = height;
int _channels = img.channels();
int channels = _channels > 1 ? 3 : 1;
cinfo.input_components = channels;
cinfo.in_color_space = channels > 1 ? JCS_RGB : JCS_GRAYSCALE;
int quality = 95;
int progressive = 0;
int optimize = 0;
int rst_interval = 0;
int luma_quality = -1;
int chroma_quality = -1;
for( size_t i = 0; i < params.size(); i += 2 )
{
if( params[i] == CV_IMWRITE_JPEG_QUALITY )
{
quality = params[i+1];
quality = MIN(MAX(quality, 0), 100);
}
if( params[i] == CV_IMWRITE_JPEG_PROGRESSIVE )
{
progressive = params[i+1];
}
if( params[i] == CV_IMWRITE_JPEG_OPTIMIZE )
{
optimize = params[i+1];
}
if( params[i] == CV_IMWRITE_JPEG_LUMA_QUALITY )
{
if (params[i+1] >= 0)
{
luma_quality = MIN(MAX(params[i+1], 0), 100);
quality = luma_quality;
if (chroma_quality < 0)
{
chroma_quality = luma_quality;
}
}
}
if( params[i] == CV_IMWRITE_JPEG_CHROMA_QUALITY )
{
if (params[i+1] >= 0)
{
chroma_quality = MIN(MAX(params[i+1], 0), 100);
}
}
if( params[i] == CV_IMWRITE_JPEG_RST_INTERVAL )
{
rst_interval = params[i+1];
rst_interval = MIN(MAX(rst_interval, 0), 65535L);
}
}
jpeg_set_defaults( &cinfo );
cinfo.restart_interval = rst_interval;
jpeg_set_quality( &cinfo, quality,
TRUE /* limit to baseline-JPEG values */ );
if( progressive )
jpeg_simple_progression( &cinfo );
if( optimize )
cinfo.optimize_coding = TRUE;
#if JPEG_LIB_VERSION >= 70
if (luma_quality >= 0 && chroma_quality >= 0)
{
cinfo.q_scale_factor[0] = jpeg_quality_scaling(luma_quality);
cinfo.q_scale_factor[1] = jpeg_quality_scaling(chroma_quality);
if ( luma_quality != chroma_quality )
{
/* disable subsampling - ref. Libjpeg.txt */
cinfo.comp_info[0].v_samp_factor = 1;
cinfo.comp_info[0].h_samp_factor = 1;
cinfo.comp_info[1].v_samp_factor = 1;
cinfo.comp_info[1].h_samp_factor = 1;
}
jpeg_default_qtables( &cinfo, TRUE );
}
#endif // #if JPEG_LIB_VERSION >= 70
jpeg_start_compress( &cinfo, TRUE );
if( channels > 1 )
_buffer.allocate(width*channels);
buffer = _buffer;
for( int y = 0; y < height; y++ )
{
uchar *data = img.data + img.step*y, *ptr = data;
if( _channels == 3 )
{
icvCvt_BGR2RGB_8u_C3R( data, 0, buffer, 0, cvSize(width,1) );
ptr = buffer;
}
else if( _channels == 4 )
{
icvCvt_BGRA2BGR_8u_C4C3R( data, 0, buffer, 0, cvSize(width,1), 2 );
ptr = buffer;
}
jpeg_write_scanlines( &cinfo, &ptr, 1 );
}
jpeg_finish_compress( &cinfo );
result = true;
}
_exit_:
if(!result)
{
char jmsg_buf[JMSG_LENGTH_MAX];
jerr.pub.format_message((j_common_ptr)&cinfo, jmsg_buf);
m_last_error = jmsg_buf;
}
jpeg_destroy_compress( &cinfo );
return result;
}
