add_huff_table jpeg_add_quant_table jpeg_default_colorspace jpeg_default_qtables JPEG_INTERNALS jpeg_quality_scaling jpeg_set_colorspace jpeg_set_defaults jpeg_set_linear_quality jpeg_set_quality SET_COMP std_chrominance_quant_tbl std_huff_tables std_luminance_quant_tbl

jpeg_quality_scaling ( int  quality ) Definition at line 123 of file jcparam.c. Referenced by jpeg_set_quality(), and set_quality_ratings(). { /* Safety limit on quality factor. Convert 0 to 1 to avoid zero divide. */ if (quality <= 0) quality = 1; if (quality > 100) quality = 100; /* The basic table is used as-is (scaling 100) for a quality of 50. * Qualities 50..100 are converted to scaling percentage 200 - 2*Q; * note that at Q=100 the scaling is 0, which will cause jpeg_add_quant_table * to make all the table entries 1 (hence, minimum quantization loss). * Qualities 1..50 are converted to scaling percentage 5000/Q. */ if (quality < 50) quality = 5000 / quality; else quality = 200 - quality*2; return quality; }