diff options
Diffstat (limited to 'jpeg/jcparam.c')
| -rw-r--r-- | jpeg/jcparam.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/jpeg/jcparam.c b/jpeg/jcparam.c index 3b7014ff..261ae86c 100644 --- a/jpeg/jcparam.c +++ b/jpeg/jcparam.c @@ -2,7 +2,7 @@ * jcparam.c * * Copyright (C) 1991-1998, Thomas G. Lane. - * Modified 2003-2019 by Guido Vollbeding. + * Modified 2003-2022 by Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * @@ -62,8 +62,9 @@ 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. + * NOTE: chrominance DC value is changed from 17 to 16 for lossless support. + * 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, @@ -76,7 +77,7 @@ static const unsigned int std_luminance_quant_tbl[DCTSIZE2] = { 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, + 16, 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, @@ -379,11 +380,13 @@ jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace) case JCS_RGB: cinfo->write_Adobe_marker = TRUE; /* write Adobe marker to flag RGB */ cinfo->num_components = 3; - SET_COMP(0, 0x52 /* 'R' */, 1,1, 0, + SET_COMP(0, 0x52 /* 'R' */, 1,1, + cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0); SET_COMP(1, 0x47 /* 'G' */, 1,1, 0, 0,0); - SET_COMP(2, 0x42 /* 'B' */, 1,1, 0, + SET_COMP(2, 0x42 /* 'B' */, 1,1, + cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0); break; @@ -417,11 +420,13 @@ jpeg_set_colorspace (j_compress_ptr cinfo, J_COLOR_SPACE colorspace) cinfo->JFIF_major_version = 2; /* Set JFIF major version = 2 */ cinfo->num_components = 3; /* Add offset 0x20 to the normal R/G/B component IDs */ - SET_COMP(0, 0x72 /* 'r' */, 1,1, 0, + SET_COMP(0, 0x72 /* 'r' */, 1,1, + cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0); SET_COMP(1, 0x67 /* 'g' */, 1,1, 0, 0,0); - SET_COMP(2, 0x62 /* 'b' */, 1,1, 0, + SET_COMP(2, 0x62 /* 'b' */, 1,1, + cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0, cinfo->color_transform == JCT_SUBTRACT_GREEN ? 1 : 0); break; |