diff options
Diffstat (limited to 'jcparam.c')
| -rw-r--r-- | jcparam.c | 68 |
1 files changed, 43 insertions, 25 deletions
@@ -60,6 +60,47 @@ jpeg_add_quant_table (j_compress_ptr cinfo, int which_tbl, } +/* These are the sample quantization tables given in JPEG spec section K.1. + * The spec says that the values given produce "good" quality, and + * when divided by 2, "very good" quality. + */ +static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = { + 16, 11, 10, 16, 24, 40, 51, 61, + 12, 12, 14, 19, 26, 58, 60, 55, + 14, 13, 16, 24, 40, 57, 69, 56, + 14, 17, 22, 29, 51, 87, 80, 62, + 18, 22, 37, 56, 68, 109, 103, 77, + 24, 35, 55, 64, 81, 104, 113, 92, + 49, 64, 78, 87, 103, 121, 120, 101, + 72, 92, 95, 98, 112, 100, 103, 99 +}; +static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = { + 17, 18, 24, 47, 99, 99, 99, 99, + 18, 21, 26, 66, 99, 99, 99, 99, + 24, 26, 56, 99, 99, 99, 99, 99, + 47, 66, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99, + 99, 99, 99, 99, 99, 99, 99, 99 +}; + + +GLOBAL(void) +jpeg_default_qtables (j_compress_ptr cinfo, boolean force_baseline) +/* Set or change the 'quality' (quantization) setting, using default tables + * and straight percentage-scaling quality scales. + * This entry point allows different scalings for luminance and chrominance. + */ +{ + /* Set up two quantization tables using the specified scaling */ + jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl, + cinfo->q_scale_factor[0], force_baseline); + jpeg_add_quant_table(cinfo, 1, std_chrominance_quant_tbl, + cinfo->q_scale_factor[1], force_baseline); +} + + GLOBAL(void) jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor, boolean force_baseline) @@ -69,31 +110,6 @@ jpeg_set_linear_quality (j_compress_ptr cinfo, int scale_factor, * applications that insist on a linear percentage scaling. */ { - /* These are the sample quantization tables given in JPEG spec section K.1. - * The spec says that the values given produce "good" quality, and - * when divided by 2, "very good" quality. - */ - static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = { - 16, 11, 10, 16, 24, 40, 51, 61, - 12, 12, 14, 19, 26, 58, 60, 55, - 14, 13, 16, 24, 40, 57, 69, 56, - 14, 17, 22, 29, 51, 87, 80, 62, - 18, 22, 37, 56, 68, 109, 103, 77, - 24, 35, 55, 64, 81, 104, 113, 92, - 49, 64, 78, 87, 103, 121, 120, 101, - 72, 92, 95, 98, 112, 100, 103, 99 - }; - static const unsigned int std_chrominance_quant_tbl[DCTSIZE2] = { - 17, 18, 24, 47, 99, 99, 99, 99, - 18, 21, 26, 66, 99, 99, 99, 99, - 24, 26, 56, 99, 99, 99, 99, 99, - 47, 66, 99, 99, 99, 99, 99, 99, - 99, 99, 99, 99, 99, 99, 99, 99, - 99, 99, 99, 99, 99, 99, 99, 99, - 99, 99, 99, 99, 99, 99, 99, 99, - 99, 99, 99, 99, 99, 99, 99, 99 - }; - /* Set up two quantization tables using the specified scaling */ jpeg_add_quant_table(cinfo, 0, std_luminance_quant_tbl, scale_factor, force_baseline); @@ -284,6 +300,8 @@ jpeg_set_defaults (j_compress_ptr cinfo) /* Initialize everything not dependent on the color space */ + cinfo->scale_num = 1; /* 1:1 scaling */ + cinfo->scale_denom = 1; cinfo->data_precision = BITS_IN_JSAMPLE; /* Set up two quantization tables using default quality of 75 */ jpeg_set_quality(cinfo, 75, TRUE); |