mirror of https://github.com/fltk/fltk
Merge changes from JPEG 8c (released Jan 16, 2011)
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@8426 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
This commit is contained in:
Michael R Sweet
parent
1216e9530f
commit
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12
jpeg/README
12
jpeg/README
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@ -1,7 +1,7 @@
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The Independent JPEG Group's JPEG software
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==========================================
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README for release 8b of 16-May-2010
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README for release 8c of 16-Jan-2011
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====================================
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This distribution contains the eighth public release of the Independent JPEG
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@ -114,7 +114,7 @@ with respect to this software, its quality, accuracy, merchantability, or
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fitness for a particular purpose. This software is provided "AS IS", and you,
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its user, assume the entire risk as to its quality and accuracy.
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This software is copyright (C) 1991-2010, Thomas G. Lane, Guido Vollbeding.
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This software is copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding.
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All Rights Reserved except as specified below.
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Permission is hereby granted to use, copy, modify, and distribute this
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@ -254,8 +254,8 @@ ARCHIVE LOCATIONS
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The "official" archive site for this software is www.ijg.org.
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The most recent released version can always be found there in
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directory "files". This particular version will be archived as
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http://www.ijg.org/files/jpegsrc.v8b.tar.gz, and in Windows-compatible
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"zip" archive format as http://www.ijg.org/files/jpegsr8b.zip.
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http://www.ijg.org/files/jpegsrc.v8c.tar.gz, and in Windows-compatible
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"zip" archive format as http://www.ijg.org/files/jpegsr8c.zip.
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The JPEG FAQ (Frequently Asked Questions) article is a source of some
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general information about JPEG.
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@ -285,8 +285,8 @@ Thank to John Korejwa and Massimo Ballerini for inviting me to
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fruitful consultations in Boston, MA and Milan, Italy.
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Thank to Hendrik Elstner, Roland Fassauer, Simone Zuck, Guenther
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Maier-Gerber, Walter Stoeber, and Fred Schmitz for corresponding
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business development.
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Maier-Gerber, Walter Stoeber, Fred Schmitz, and Norbert Braunagel
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for corresponding business development.
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Thank to Nico Zschach and Dirk Stelling of the technical support team
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at the Digital Images company in Halle for providing me with extra
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@ -1,6 +1,17 @@
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CHANGE LOG for Independent JPEG Group's JPEG software
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Version 8c 16-Jan-2011
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-----------------------
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Add option to compression library and cjpeg (-block N) to use
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different DCT block size.
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All N from 1 to 16 are possible. Default is 8 (baseline format).
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Larger values produce higher compression,
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smaller values produce higher quality.
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SmartScale capable decoder (introduced with IJG JPEG 8) required.
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Version 8b 16-May-2010
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-----------------------
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@ -2,7 +2,7 @@
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* jcmarker.c
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*
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* Copyright (C) 1991-1998, Thomas G. Lane.
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* Modified 2003-2009 by Guido Vollbeding.
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* Modified 2003-2010 by Guido Vollbeding.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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@ -231,10 +231,10 @@ emit_dac (j_compress_ptr cinfo)
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char ac_in_use[NUM_ARITH_TBLS];
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int length, i;
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jpeg_component_info *compptr;
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for (i = 0; i < NUM_ARITH_TBLS; i++)
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dc_in_use[i] = ac_in_use[i] = 0;
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for (i = 0; i < cinfo->comps_in_scan; i++) {
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compptr = cinfo->cur_comp_info[i];
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/* DC needs no table for refinement scan */
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@ -244,23 +244,25 @@ emit_dac (j_compress_ptr cinfo)
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if (cinfo->Se)
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ac_in_use[compptr->ac_tbl_no] = 1;
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}
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length = 0;
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for (i = 0; i < NUM_ARITH_TBLS; i++)
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length += dc_in_use[i] + ac_in_use[i];
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emit_marker(cinfo, M_DAC);
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emit_2bytes(cinfo, length*2 + 2);
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for (i = 0; i < NUM_ARITH_TBLS; i++) {
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if (dc_in_use[i]) {
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emit_byte(cinfo, i);
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emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
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}
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if (ac_in_use[i]) {
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emit_byte(cinfo, i + 0x10);
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emit_byte(cinfo, cinfo->arith_ac_K[i]);
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if (length) {
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emit_marker(cinfo, M_DAC);
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emit_2bytes(cinfo, length*2 + 2);
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for (i = 0; i < NUM_ARITH_TBLS; i++) {
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if (dc_in_use[i]) {
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emit_byte(cinfo, i);
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emit_byte(cinfo, cinfo->arith_dc_L[i] + (cinfo->arith_dc_U[i]<<4));
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}
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if (ac_in_use[i]) {
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emit_byte(cinfo, i + 0x10);
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emit_byte(cinfo, cinfo->arith_ac_K[i]);
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}
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}
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}
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#endif /* C_ARITH_CODING_SUPPORTED */
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194
jpeg/jcmaster.c
194
jpeg/jcmaster.c
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@ -2,7 +2,7 @@
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* jcmaster.c
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*
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* Copyright (C) 1991-1997, Thomas G. Lane.
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* Modified 2003-2010 by Guido Vollbeding.
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* Modified 2003-2011 by Guido Vollbeding.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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@ -55,125 +55,140 @@ jpeg_calc_jpeg_dimensions (j_compress_ptr cinfo)
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{
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#ifdef DCT_SCALING_SUPPORTED
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/* Sanity check on input image dimensions to prevent overflow in
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* following calculation.
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* We do check jpeg_width and jpeg_height in initial_setup below,
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* but image_width and image_height can come from arbitrary data,
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* and we need some space for multiplication by block_size.
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*/
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if (((long) cinfo->image_width >> 24) || ((long) cinfo->image_height >> 24))
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ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
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/* Compute actual JPEG image dimensions and DCT scaling choices. */
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if (cinfo->scale_num >= cinfo->scale_denom * 8) {
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/* Provide 8/1 scaling */
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cinfo->jpeg_width = cinfo->image_width << 3;
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cinfo->jpeg_height = cinfo->image_height << 3;
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if (cinfo->scale_num >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/1 scaling */
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cinfo->jpeg_width = cinfo->image_width * cinfo->block_size;
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cinfo->jpeg_height = cinfo->image_height * cinfo->block_size;
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cinfo->min_DCT_h_scaled_size = 1;
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cinfo->min_DCT_v_scaled_size = 1;
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} else if (cinfo->scale_num >= cinfo->scale_denom * 4) {
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/* Provide 4/1 scaling */
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cinfo->jpeg_width = cinfo->image_width << 2;
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cinfo->jpeg_height = cinfo->image_height << 2;
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} else if (cinfo->scale_num * 2 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/2 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 2L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 2L);
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cinfo->min_DCT_h_scaled_size = 2;
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cinfo->min_DCT_v_scaled_size = 2;
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} else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 8) {
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/* Provide 8/3 scaling */
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cinfo->jpeg_width = (cinfo->image_width << 1) + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 2, 3L);
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cinfo->jpeg_height = (cinfo->image_height << 1) + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 2, 3L);
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} else if (cinfo->scale_num * 3 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/3 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 3L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 3L);
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cinfo->min_DCT_h_scaled_size = 3;
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cinfo->min_DCT_v_scaled_size = 3;
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} else if (cinfo->scale_num >= cinfo->scale_denom * 2) {
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/* Provide 2/1 scaling */
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cinfo->jpeg_width = cinfo->image_width << 1;
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cinfo->jpeg_height = cinfo->image_height << 1;
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} else if (cinfo->scale_num * 4 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/4 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 4L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 4L);
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cinfo->min_DCT_h_scaled_size = 4;
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cinfo->min_DCT_v_scaled_size = 4;
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} else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 8) {
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/* Provide 8/5 scaling */
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cinfo->jpeg_width = cinfo->image_width + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 3, 5L);
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cinfo->jpeg_height = cinfo->image_height + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 3, 5L);
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} else if (cinfo->scale_num * 5 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/5 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 5L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 5L);
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cinfo->min_DCT_h_scaled_size = 5;
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cinfo->min_DCT_v_scaled_size = 5;
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} else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 4) {
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/* Provide 4/3 scaling */
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cinfo->jpeg_width = cinfo->image_width + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width, 3L);
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cinfo->jpeg_height = cinfo->image_height + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height, 3L);
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} else if (cinfo->scale_num * 6 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/6 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 6L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 6L);
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cinfo->min_DCT_h_scaled_size = 6;
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cinfo->min_DCT_v_scaled_size = 6;
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} else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 8) {
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/* Provide 8/7 scaling */
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cinfo->jpeg_width = cinfo->image_width + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width, 7L);
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cinfo->jpeg_height = cinfo->image_height + (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height, 7L);
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} else if (cinfo->scale_num * 7 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/7 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 7L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 7L);
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cinfo->min_DCT_h_scaled_size = 7;
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cinfo->min_DCT_v_scaled_size = 7;
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} else if (cinfo->scale_num >= cinfo->scale_denom) {
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/* Provide 1/1 scaling */
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cinfo->jpeg_width = cinfo->image_width;
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cinfo->jpeg_height = cinfo->image_height;
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} else if (cinfo->scale_num * 8 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/8 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 8L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 8L);
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cinfo->min_DCT_h_scaled_size = 8;
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cinfo->min_DCT_v_scaled_size = 8;
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} else if (cinfo->scale_num * 9 >= cinfo->scale_denom * 8) {
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/* Provide 8/9 scaling */
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} else if (cinfo->scale_num * 9 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/9 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 8, 9L);
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 9L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 8, 9L);
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 9L);
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cinfo->min_DCT_h_scaled_size = 9;
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cinfo->min_DCT_v_scaled_size = 9;
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} else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 4) {
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/* Provide 4/5 scaling */
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} else if (cinfo->scale_num * 10 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/10 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 4, 5L);
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 10L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 4, 5L);
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 10L);
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cinfo->min_DCT_h_scaled_size = 10;
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cinfo->min_DCT_v_scaled_size = 10;
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} else if (cinfo->scale_num * 11 >= cinfo->scale_denom * 8) {
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/* Provide 8/11 scaling */
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} else if (cinfo->scale_num * 11 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/11 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 8, 11L);
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 11L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 8, 11L);
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 11L);
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cinfo->min_DCT_h_scaled_size = 11;
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cinfo->min_DCT_v_scaled_size = 11;
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} else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 2) {
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/* Provide 2/3 scaling */
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} else if (cinfo->scale_num * 12 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/12 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 2, 3L);
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 12L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 2, 3L);
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 12L);
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cinfo->min_DCT_h_scaled_size = 12;
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cinfo->min_DCT_v_scaled_size = 12;
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} else if (cinfo->scale_num * 13 >= cinfo->scale_denom * 8) {
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/* Provide 8/13 scaling */
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} else if (cinfo->scale_num * 13 >= cinfo->scale_denom * cinfo->block_size) {
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/* Provide block_size/13 scaling */
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cinfo->jpeg_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * 8, 13L);
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 13L);
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cinfo->jpeg_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * 8, 13L);
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 13L);
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cinfo->min_DCT_h_scaled_size = 13;
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cinfo->min_DCT_v_scaled_size = 13;
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} else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 4) {
|
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/* Provide 4/7 scaling */
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} else if (cinfo->scale_num * 14 >= cinfo->scale_denom * cinfo->block_size) {
|
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/* Provide block_size/14 scaling */
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cinfo->jpeg_width = (JDIMENSION)
|
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jdiv_round_up((long) cinfo->image_width * 4, 7L);
|
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 14L);
|
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cinfo->jpeg_height = (JDIMENSION)
|
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jdiv_round_up((long) cinfo->image_height * 4, 7L);
|
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 14L);
|
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cinfo->min_DCT_h_scaled_size = 14;
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cinfo->min_DCT_v_scaled_size = 14;
|
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} else if (cinfo->scale_num * 15 >= cinfo->scale_denom * 8) {
|
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/* Provide 8/15 scaling */
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} else if (cinfo->scale_num * 15 >= cinfo->scale_denom * cinfo->block_size) {
|
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/* Provide block_size/15 scaling */
|
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cinfo->jpeg_width = (JDIMENSION)
|
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jdiv_round_up((long) cinfo->image_width * 8, 15L);
|
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jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 15L);
|
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cinfo->jpeg_height = (JDIMENSION)
|
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jdiv_round_up((long) cinfo->image_height * 8, 15L);
|
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jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 15L);
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cinfo->min_DCT_h_scaled_size = 15;
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cinfo->min_DCT_v_scaled_size = 15;
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} else {
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/* Provide 1/2 scaling */
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/* Provide block_size/16 scaling */
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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 @@ jpeg_calc_jpeg_dimensions (j_compress_ptr cinfo)
|
|||
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 @@ initial_setup (j_compress_ptr cinfo, boolean transcode_only)
|
|||
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)
|
||||
|
|
|
|||
|
|
@ -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 @@ extern "C" {
|
|||
#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.
|
||||
|
|
|
|||
|
|
@ -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"
|
||||
|
|
|
|||
|
|
@ -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 @@ jpeg_simple_progression (j_compress_ptr cinfo)
|
|||
|
||||
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 @@ J_DCT_METHOD dct_method
|
|||
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
|
||||
|
|
|
|||
|
|
@ -87,8 +87,9 @@ The basic command line switches for cjpeg are:
|
|||
-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 @@ file size is about the same --- often a little smaller.
|
|||
|
||||
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.
|
||||
|
|
|
|||
Loading…
Reference in New Issue