Author: mike Date: 2011-02-15 07:28:27 -0800 (Tue, 15 Feb 2011) New Revision: 8426 Log: Merge changes from JPEG 8c (released Jan 16, 2011)
Modified: branches/branch-1.3/jpeg/README branches/branch-1.3/jpeg/change.log branches/branch-1.3/jpeg/jcmarker.c branches/branch-1.3/jpeg/jcmaster.c branches/branch-1.3/jpeg/jpeglib.h branches/branch-1.3/jpeg/jversion.h branches/branch-1.3/jpeg/libjpeg.txt branches/branch-1.3/jpeg/usage.txt Modified: branches/branch-1.3/jpeg/README =================================================================== --- branches/branch-1.3/jpeg/README 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/README 2011-02-15 15:28:27 UTC (rev 8426) @@ -1,7 +1,7 @@ The Independent JPEG Group's JPEG software ========================================== -README for release 8b of 16-May-2010 +README for release 8c of 16-Jan-2011 ==================================== This distribution contains the eighth public release of the Independent JPEG @@ -114,7 +114,7 @@ fitness for a particular purpose. This software is provided "AS IS", and you, its user, assume the entire risk as to its quality and accuracy. -This software is copyright (C) 1991-2010, Thomas G. Lane, Guido Vollbeding. +This software is copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding. All Rights Reserved except as specified below. Permission is hereby granted to use, copy, modify, and distribute this @@ -254,8 +254,8 @@ The "official" archive site for this software is www.ijg.org. The most recent released version can always be found there in directory "files". This particular version will be archived as -http://www.ijg.org/files/jpegsrc.v8b.tar.gz, and in Windows-compatible -"zip" archive format as http://www.ijg.org/files/jpegsr8b.zip. +http://www.ijg.org/files/jpegsrc.v8c.tar.gz, and in Windows-compatible +"zip" archive format as http://www.ijg.org/files/jpegsr8c.zip. The JPEG FAQ (Frequently Asked Questions) article is a source of some general information about JPEG. @@ -285,8 +285,8 @@ fruitful consultations in Boston, MA and Milan, Italy. Thank to Hendrik Elstner, Roland Fassauer, Simone Zuck, Guenther -Maier-Gerber, Walter Stoeber, and Fred Schmitz for corresponding -business development. +Maier-Gerber, Walter Stoeber, Fred Schmitz, and Norbert Braunagel +for corresponding business development. Thank to Nico Zschach and Dirk Stelling of the technical support team at the Digital Images company in Halle for providing me with extra Modified: branches/branch-1.3/jpeg/change.log =================================================================== --- branches/branch-1.3/jpeg/change.log 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/change.log 2011-02-15 15:28:27 UTC (rev 8426) @@ -1,6 +1,17 @@ CHANGE LOG for Independent JPEG Group's JPEG software +Version 8c 16-Jan-2011 +----------------------- + +Add option to compression library and cjpeg (-block N) to use +different DCT block size. +All N from 1 to 16 are possible. Default is 8 (baseline format). +Larger values produce higher compression, +smaller values produce higher quality. +SmartScale capable decoder (introduced with IJG JPEG 8) required. + + Version 8b 16-May-2010 ----------------------- Modified: branches/branch-1.3/jpeg/jcmarker.c =================================================================== --- branches/branch-1.3/jpeg/jcmarker.c 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/jcmarker.c 2011-02-15 15:28:27 UTC (rev 8426) @@ -2,7 +2,7 @@ * jcmarker.c * * Copyright (C) 1991-1998, Thomas G. Lane. - * Modified 2003-2009 by Guido Vollbeding. + * Modified 2003-2010 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. * @@ -231,10 +231,10 @@ char ac_in_use[NUM_ARITH_TBLS]; int length, i; jpeg_component_info *compptr; - + for (i = 0; i < NUM_ARITH_TBLS; i++) dc_in_use[i] = ac_in_use[i] = 0; - + for (i = 0; i < cinfo->comps_in_scan; i++) { compptr = cinfo->cur_comp_info[i]; /* DC needs no table for refinement scan */ @@ -244,24 +244,26 @@ if (cinfo->Se) ac_in_use[compptr->ac_tbl_no] = 1; } - + length = 0; for (i = 0; i < NUM_ARITH_TBLS; i++) length += dc_in_use[i] + ac_in_use[i]; - - emit_marker(cinfo, M_DAC); - - emit_2bytes(cinfo, length*2 + 2); - - for (i = 0; i < NUM_ARITH_TBLS; i++) { - if (dc_in_use[i]) { - emit_byte(cinfo, i); - emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4)); + + if (length) { + emit_marker(cinfo, M_DAC); + + emit_2bytes(cinfo, length*2 + 2); + + for (i = 0; i < NUM_ARITH_TBLS; i++) { + if (dc_in_use[i]) { + emit_byte(cinfo, i); + emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4)); + } + if (ac_in_use[i]) { + emit_byte(cinfo, i + 0x10); + emit_byte(cinfo, cinfo->arith_ac_K[i]); + } } - if (ac_in_use[i]) { - emit_byte(cinfo, i + 0x10); - emit_byte(cinfo, cinfo->arith_ac_K[i]); - } } #endif /* C_ARITH_CODING_SUPPORTED */ } Modified: branches/branch-1.3/jpeg/jcmaster.c =================================================================== --- branches/branch-1.3/jpeg/jcmaster.c 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/jcmaster.c 2011-02-15 15:28:27 UTC (rev 8426) @@ -2,7 +2,7 @@ * jcmaster.c * * Copyright (C) 1991-1997, Thomas G. Lane. - * Modified 2003-2010 by Guido Vollbeding. + * Modified 2003-2011 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. * @@ -55,125 +55,140 @@ { #ifdef DCT_SCALING_SUPPORTED + /* Sanity check on input image dimensions to prevent overflow in + * following calculation. + * We do check jpeg_width and jpeg_height in initial_setup below, + * but image_width and image_height can come from arbitrary data, + * and we need some space for multiplication by block_size. + */ + if (((long) cinfo->image_width >> 24) || ((long) cinfo->image_height >> 24)) + ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); + /* Compute actual JPEG image dimensions and DCT scaling choices. */ - if (cinfo->scale_num >= cinfo->scale_denom * 8) { - /* Provide 8/1 scaling */ - cinfo->jpeg_width = cinfo->image_width << 3; - cinfo->jpeg_height = cinfo->image_height << 3; + if (cinfo->scale_num >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/1 scaling */ + cinfo->jpeg_width = cinfo->image_width * cinfo->block_size; + cinfo->jpeg_height = cinfo->image_height * cinfo->block_size; cinfo->min_DCT_h_scaled_size = 1; cinfo->min_DCT_v_scaled_size = 1; - } else if (cinfo->scale_num >= cinfo->scale_denom * 4) { - /* Provide 4/1 scaling */ - cinfo->jpeg_width = cinfo->image_width << 2; - cinfo->jpeg_height = cinfo->image_height << 2; + } else if (cinfo->scale_num * 2 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/2 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 2L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 2L); cinfo->min_DCT_h_scaled_size = 2; cinfo->min_DCT_v_scaled_size = 2; - } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 8) { - /* Provide 8/3 scaling */ - cinfo->jpeg_width = (cinfo->image_width << 1) + (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 2, 3L); - cinfo->jpeg_height = (cinfo->image_height << 1) + (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 2, 3L); + } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/3 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 3L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 3L); cinfo->min_DCT_h_scaled_size = 3; cinfo->min_DCT_v_scaled_size = 3; - } else if (cinfo->scale_num >= cinfo->scale_denom * 2) { - /* Provide 2/1 scaling */ - cinfo->jpeg_width = cinfo->image_width << 1; - cinfo->jpeg_height = cinfo->image_height << 1; + } else if (cinfo->scale_num * 4 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/4 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 4L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 4L); cinfo->min_DCT_h_scaled_size = 4; cinfo->min_DCT_v_scaled_size = 4; - } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 8) { - /* Provide 8/5 scaling */ - cinfo->jpeg_width = cinfo->image_width + (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 3, 5L); - cinfo->jpeg_height = cinfo->image_height + (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 3, 5L); + } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/5 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 5L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 5L); cinfo->min_DCT_h_scaled_size = 5; cinfo->min_DCT_v_scaled_size = 5; - } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 4) { - /* Provide 4/3 scaling */ - cinfo->jpeg_width = cinfo->image_width + (JDIMENSION) - jdiv_round_up((long) cinfo->image_width, 3L); - cinfo->jpeg_height = cinfo->image_height + (JDIMENSION) - jdiv_round_up((long) cinfo->image_height, 3L); + } else if (cinfo->scale_num * 6 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/6 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 6L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 6L); cinfo->min_DCT_h_scaled_size = 6; cinfo->min_DCT_v_scaled_size = 6; - } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 8) { - /* Provide 8/7 scaling */ - cinfo->jpeg_width = cinfo->image_width + (JDIMENSION) - jdiv_round_up((long) cinfo->image_width, 7L); - cinfo->jpeg_height = cinfo->image_height + (JDIMENSION) - jdiv_round_up((long) cinfo->image_height, 7L); + } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/7 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 7L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 7L); cinfo->min_DCT_h_scaled_size = 7; cinfo->min_DCT_v_scaled_size = 7; - } else if (cinfo->scale_num >= cinfo->scale_denom) { - /* Provide 1/1 scaling */ - cinfo->jpeg_width = cinfo->image_width; - cinfo->jpeg_height = cinfo->image_height; + } else if (cinfo->scale_num * 8 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/8 scaling */ + cinfo->jpeg_width = (JDIMENSION) + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 8L); + cinfo->jpeg_height = (JDIMENSION) + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 8L); cinfo->min_DCT_h_scaled_size = 8; cinfo->min_DCT_v_scaled_size = 8; - } else if (cinfo->scale_num * 9 >= cinfo->scale_denom * 8) { - /* Provide 8/9 scaling */ + } else if (cinfo->scale_num * 9 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/9 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 8, 9L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 9L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 8, 9L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 9L); cinfo->min_DCT_h_scaled_size = 9; cinfo->min_DCT_v_scaled_size = 9; - } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 4) { - /* Provide 4/5 scaling */ + } else if (cinfo->scale_num * 10 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/10 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 4, 5L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 10L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 4, 5L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 10L); cinfo->min_DCT_h_scaled_size = 10; cinfo->min_DCT_v_scaled_size = 10; - } else if (cinfo->scale_num * 11 >= cinfo->scale_denom * 8) { - /* Provide 8/11 scaling */ + } else if (cinfo->scale_num * 11 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/11 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 8, 11L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 11L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 8, 11L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 11L); cinfo->min_DCT_h_scaled_size = 11; cinfo->min_DCT_v_scaled_size = 11; - } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 2) { - /* Provide 2/3 scaling */ + } else if (cinfo->scale_num * 12 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/12 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 2, 3L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 12L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 2, 3L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 12L); cinfo->min_DCT_h_scaled_size = 12; cinfo->min_DCT_v_scaled_size = 12; - } else if (cinfo->scale_num * 13 >= cinfo->scale_denom * 8) { - /* Provide 8/13 scaling */ + } else if (cinfo->scale_num * 13 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/13 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 8, 13L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 13L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 8, 13L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 13L); cinfo->min_DCT_h_scaled_size = 13; cinfo->min_DCT_v_scaled_size = 13; - } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 4) { - /* Provide 4/7 scaling */ + } else if (cinfo->scale_num * 14 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/14 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 4, 7L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 14L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 4, 7L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 14L); cinfo->min_DCT_h_scaled_size = 14; cinfo->min_DCT_v_scaled_size = 14; - } else if (cinfo->scale_num * 15 >= cinfo->scale_denom * 8) { - /* Provide 8/15 scaling */ + } else if (cinfo->scale_num * 15 >= cinfo->scale_denom * cinfo->block_size) { + /* Provide block_size/15 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width * 8, 15L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 15L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height * 8, 15L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 15L); cinfo->min_DCT_h_scaled_size = 15; cinfo->min_DCT_v_scaled_size = 15; } else { - /* Provide 1/2 scaling */ + /* Provide block_size/16 scaling */ cinfo->jpeg_width = (JDIMENSION) - jdiv_round_up((long) cinfo->image_width, 2L); + jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 16L); cinfo->jpeg_height = (JDIMENSION) - jdiv_round_up((long) cinfo->image_height, 2L); + jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 16L); cinfo->min_DCT_h_scaled_size = 16; cinfo->min_DCT_v_scaled_size = 16; } @@ -193,25 +208,11 @@ LOCAL(void) jpeg_calc_trans_dimensions (j_compress_ptr cinfo) { - if (cinfo->min_DCT_h_scaled_size < 1 || cinfo->min_DCT_h_scaled_size > 16 - || cinfo->min_DCT_h_scaled_size != cinfo->min_DCT_v_scaled_size) + if (cinfo->min_DCT_h_scaled_size != cinfo->min_DCT_v_scaled_size) ERREXIT2(cinfo, JERR_BAD_DCTSIZE, cinfo->min_DCT_h_scaled_size, cinfo->min_DCT_v_scaled_size); cinfo->block_size = cinfo->min_DCT_h_scaled_size; - - switch (cinfo->block_size) { - case 2: cinfo->natural_order = jpeg_natural_order2; break; - case 3: cinfo->natural_order = jpeg_natural_order3; break; - case 4: cinfo->natural_order = jpeg_natural_order4; break; - case 5: cinfo->natural_order = jpeg_natural_order5; break; - case 6: cinfo->natural_order = jpeg_natural_order6; break; - case 7: cinfo->natural_order = jpeg_natural_order7; break; - default: cinfo->natural_order = jpeg_natural_order; break; - } - - cinfo->lim_Se = cinfo->block_size < DCTSIZE ? - cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1; } @@ -229,6 +230,25 @@ else jpeg_calc_jpeg_dimensions(cinfo); + /* Sanity check on block_size */ + if (cinfo->block_size < 1 || cinfo->block_size > 16) + ERREXIT2(cinfo, JERR_BAD_DCTSIZE, cinfo->block_size, cinfo->block_size); + + /* Derive natural_order from block_size */ + switch (cinfo->block_size) { + case 2: cinfo->natural_order = jpeg_natural_order2; break; + case 3: cinfo->natural_order = jpeg_natural_order3; break; + case 4: cinfo->natural_order = jpeg_natural_order4; break; + case 5: cinfo->natural_order = jpeg_natural_order5; break; + case 6: cinfo->natural_order = jpeg_natural_order6; break; + case 7: cinfo->natural_order = jpeg_natural_order7; break; + default: cinfo->natural_order = jpeg_natural_order; break; + } + + /* Derive lim_Se from block_size */ + cinfo->lim_Se = cinfo->block_size < DCTSIZE ? + cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1; + /* Sanity check on image dimensions */ if (cinfo->jpeg_height <= 0 || cinfo->jpeg_width <= 0 || cinfo->num_components <= 0 || cinfo->input_components <= 0) Modified: branches/branch-1.3/jpeg/jpeglib.h =================================================================== --- branches/branch-1.3/jpeg/jpeglib.h 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/jpeglib.h 2011-02-15 15:28:27 UTC (rev 8426) @@ -2,7 +2,7 @@ * jpeglib.h * * Copyright (C) 1991-1998, Thomas G. Lane. - * Modified 2002-2009 by Guido Vollbeding. + * Modified 2002-2010 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. * @@ -33,11 +33,13 @@ #endif #endif -/* Version ID for the JPEG library. +/* Version IDs for the JPEG library. * Might be useful for tests like "#if JPEG_LIB_VERSION >= 80". */ -#define JPEG_LIB_VERSION 80 /* Version 8.0 */ +#define JPEG_LIB_VERSION 80 /* Compatibility version 8.0 */ +#define JPEG_LIB_VERSION_MAJOR 8 +#define JPEG_LIB_VERSION_MINOR 3 /* Various constants determining the sizes of things. Modified: branches/branch-1.3/jpeg/jversion.h =================================================================== --- branches/branch-1.3/jpeg/jversion.h 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/jversion.h 2011-02-15 15:28:27 UTC (rev 8426) @@ -1,7 +1,7 @@ /* * jversion.h * - * Copyright (C) 1991-2010, Thomas G. Lane, Guido Vollbeding. + * Copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * @@ -9,6 +9,6 @@ */ -#define JVERSION "8b 16-May-2010" +#define JVERSION "8c 16-Jan-2011" -#define JCOPYRIGHT "Copyright (C) 2010, Thomas G. Lane, Guido Vollbeding" +#define JCOPYRIGHT "Copyright (C) 2011, Thomas G. Lane, Guido Vollbeding" Modified: branches/branch-1.3/jpeg/libjpeg.txt =================================================================== --- branches/branch-1.3/jpeg/libjpeg.txt 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/libjpeg.txt 2011-02-15 15:28:27 UTC (rev 8426) @@ -1,6 +1,6 @@ USING THE IJG JPEG LIBRARY -Copyright (C) 1994-2009, Thomas G. Lane, Guido Vollbeding. +Copyright (C) 1994-2010, Thomas G. Lane, Guido Vollbeding. This file is part of the Independent JPEG Group's software. For conditions of distribution and use, see the accompanying README file. @@ -876,6 +876,18 @@ Compression parameters (cinfo fields) include: +int block_size + Set DCT block size. All N from 1 to 16 are possible. + Default is 8 (baseline format). + Larger values produce higher compression, + smaller values produce higher quality. + An exact DCT stage is possible with 1 or 2. + With the default quality of 75 and default Luminance qtable + the DCT+Quantization stage is lossless for value 1. + Note that values other than 8 require a SmartScale capable decoder, + introduced with IJG JPEG 8. Setting the block_size parameter for + compression works with version 8c and later. + J_DCT_METHOD dct_method Selects the algorithm used for the DCT step. Choices are: JDCT_ISLOW: slow but accurate integer algorithm @@ -895,8 +907,10 @@ unsigned int scale_num, scale_denom Scale the image by the fraction scale_num/scale_denom. Default is 1/1, or no scaling. Currently, the supported scaling ratios are - 8/N with all N from 1 to 16. (The library design allows for arbitrary - scaling ratios but this is not likely to be implemented any time soon.) + M/N with all N from 1 to 16, where M is the destination DCT size, + which is 8 by default (see block_size parameter above). + (The library design allows for arbitrary scaling ratios but this + is not likely to be implemented any time soon.) J_COLOR_SPACE jpeg_color_space int num_components Modified: branches/branch-1.3/jpeg/usage.txt =================================================================== --- branches/branch-1.3/jpeg/usage.txt 2011-02-15 15:25:53 UTC (rev 8425) +++ branches/branch-1.3/jpeg/usage.txt 2011-02-15 15:28:27 UTC (rev 8426) @@ -87,8 +87,9 @@ -progressive Create progressive JPEG file (see below). -scale M/N Scale the output image by a factor M/N. Currently - supported scale factors are 8/N with all N from 1 to - 16. + supported scale factors are M/N with all N from 1 to + 16, where M is the destination DCT size, which is 8 by + default (see -block N switch below). -targa Input file is Targa format. Targa files that contain an "identification" field will not be automatically @@ -150,6 +151,19 @@ Switches for advanced users: + -block N Set DCT block size. All N from 1 to 16 are possible. + Default is 8 (baseline format). + Larger values produce higher compression, + smaller values produce higher quality + (exact DCT stage possible with 1 or 2; with the + default quality of 75 and default Luminance qtable + the DCT+Quantization stage is lossless for N=1). + CAUTION: An implementation of the JPEG SmartScale + extension is required for this feature. SmartScale + enabled JPEG is not yet widely implemented, so many + decoders will be unable to view a SmartScale extended + JPEG file at all. + -dct int Use integer DCT method (default). -dct fast Use fast integer DCT (less accurate). -dct float Use floating-point DCT method. _______________________________________________ fltk-commit mailing list [email protected] http://lists.easysw.com/mailman/listinfo/fltk-commit
