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Clean up the lossless JPEG feature

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- Rename jpeg_simple_lossless() to jpeg_enable_lossless() and modify the
  function so that it stores the lossless parameters directly in the Ss
  and Al fields of jpeg_compress_struct rather than using a scan script.

- Move the cjpeg -lossless switch into "Switches for advanced users".

- Document the libjpeg API and run-time features that are unavailable in
  lossless mode, and ensure that all parameters, functions, and switches
  related to unavailable features are ignored or generate errors in
  lossless mode.

- Defer any action that depends on whether lossless mode is enabled
  until jpeg_start_compress()/jpeg_start_decompress() is called.

- Document the purpose of the point transform value.

- "Codec" stands for coder/decoder, so it is a bit awkward to say
  "lossless compression codec" and "lossless decompression codec".
  Use "lossless compressor" and "lossless decompressor" instead.

- Restore backward API/ABI compatibility with libjpeg v6b:

  * Move the new 'lossless' field from the exposed jpeg_compress_struct
    and jpeg_decompress_struct structures into the opaque
    jpeg_comp_master and jpeg_decomp_master structures, and allocate the
    master structures in the body of jpeg_create_compress() and
    jpeg_create_decompress().

  * Remove the new 'process' field from jpeg_compress_struct and
    jpeg_decompress_struct and replace it with the old
    'progressive_mode' field and the new 'lossless' field.

  * Remove the new 'data_unit' field from jpeg_compress_struct and
    jpeg_decompress_struct and replace it with a locally-computed
    data unit variable.

  * Restore the names of macros and fields that refer to DCT blocks, and
    document that they have a different meaning in lossless mode.  (Most
    of them aren't very meaningful in lossless mode anyhow.)

  * Remove the new alloc_darray() method from jpeg_memory_mgr and
    replace it with an internal macro that wraps the alloc_sarray()
    method.

  * Move the JDIFF* data types from jpeglib.h and jmorecfg.h into
    jpegint.h.

  * Remove the new 'codec' field from jpeg_compress_struct and
    jpeg_decompress_struct and instead reuse the existing internal
    coefficient control, forward/inverse DCT, and entropy
    encoding/decoding structures for lossless compression/decompression.

  * Repurpose existing error codes rather than introducing new ones.
    (The new JERR_BAD_RESTART and JWRN_MUST_DOWNSCALE codes remain,
    although JWRN_MUST_DOWNSCALE will probably be removed in
    libjpeg-turbo, since we have a different way of handling multiple
    data precisions.)

- Automatically enable lossless mode when a scan script with parameters
  that are only valid for lossless mode is detected, and document the
  use of scan scripts to generate lossless JPEG images.

- Move the sequential and shared Huffman routines back into jchuff.c and
  jdhuff.c, and document that those routines are shared with jclhuff.c
  and jdlhuff.c as well as with jcphuff.c and jdphuff.c.

- Move MAX_DIFF_BITS from jchuff.h into jclhuff.c, the only place where
  it is used.

- Move the predictor and scaler code into jclossls.c and jdlossls.c.

- Streamline register usage in the [un]differencers (inspired by similar
  optimizations in the color [de]converters.)

- Restructure the logic in a few places to reduce duplicated code.

- Ensure that all lossless-specific code is guarded by
  C_LOSSLESS_SUPPORTED or D_LOSSLESS_SUPPORTED and that the library can
  be built successfully if either or both of those macros is undefined.

- Remove all short forms of external names introduced by the lossless
  JPEG patch.  (These will not be needed by libjpeg-turbo, so there is
  no use cleaning them up.)

- Various wordsmithing, formatting, and punctuation tweaks

- Eliminate various compiler warnings.
This commit is contained in:
DRC
2022-11-08 15:01:18 -06:00
parent ec6e451d05
commit 217d1a75f5
67 changed files with 3171 additions and 3871 deletions
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55
jcphuff.c
View File

@@ -2,7 +2,7 @@
* jcphuff.c
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1995-1998, Thomas G. Lane.
* Copyright (C) 1995-1997, Thomas G. Lane.
* Lossless JPEG Modifications:
* Copyright (C) 1999, Ken Murchison.
* For conditions of distribution and use, see the accompanying README file.
@@ -17,7 +17,6 @@
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jlossy.h" /* Private declarations for lossy codec */
#include "jchuff.h" /* Declarations shared with jc*huff.c */
#ifdef C_PROGRESSIVE_SUPPORTED
@@ -25,6 +24,8 @@
/* Expanded entropy encoder object for progressive Huffman encoding. */
typedef struct {
struct jpeg_entropy_encoder pub; /* public fields */
/* Mode flag: TRUE for optimization, FALSE for actual data output */
boolean gather_statistics;
@@ -106,8 +107,7 @@ METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo));
METHODDEF(void)
start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
boolean is_DC_band;
int ci, tbl;
jpeg_component_info * compptr;
@@ -122,14 +122,14 @@ start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
/* Select execution routines */
if (cinfo->Ah == 0) {
if (is_DC_band)
lossyc->entropy_encode_mcu = encode_mcu_DC_first;
entropy->pub.encode_mcu = encode_mcu_DC_first;
else
lossyc->entropy_encode_mcu = encode_mcu_AC_first;
entropy->pub.encode_mcu = encode_mcu_AC_first;
} else {
if (is_DC_band)
lossyc->entropy_encode_mcu = encode_mcu_DC_refine;
entropy->pub.encode_mcu = encode_mcu_DC_refine;
else {
lossyc->entropy_encode_mcu = encode_mcu_AC_refine;
entropy->pub.encode_mcu = encode_mcu_AC_refine;
/* AC refinement needs a correction bit buffer */
if (entropy->bit_buffer == NULL)
entropy->bit_buffer = (char *)
@@ -138,9 +138,9 @@ start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
}
}
if (gather_statistics)
lossyc->pub.entropy_finish_pass = finish_pass_gather_phuff;
entropy->pub.finish_pass = finish_pass_gather_phuff;
else
lossyc->pub.entropy_finish_pass = finish_pass_phuff;
entropy->pub.finish_pass = finish_pass_phuff;
/* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
* for AC coefficients.
@@ -378,8 +378,7 @@ emit_restart (phuff_entropy_ptr entropy, int restart_num)
METHODDEF(boolean)
encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
register int temp, temp2;
register int nbits;
int blkn, ci;
@@ -397,7 +396,7 @@ encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
emit_restart(entropy, entropy->next_restart_num);
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->data_units_in_MCU; blkn++) {
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
ci = cinfo->MCU_membership[blkn];
compptr = cinfo->cur_comp_info[ci];
@@ -466,8 +465,7 @@ encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
METHODDEF(boolean)
encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
register int temp, temp2;
register int nbits;
register int r, k;
@@ -574,8 +572,7 @@ encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
METHODDEF(boolean)
encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
register int temp;
int blkn;
int Al = cinfo->Al;
@@ -590,7 +587,7 @@ encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
emit_restart(entropy, entropy->next_restart_num);
/* Encode the MCU data blocks */
for (blkn = 0; blkn < cinfo->data_units_in_MCU; blkn++) {
for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
block = MCU_data[blkn];
/* We simply emit the Al'th bit of the DC coefficient value. */
@@ -622,8 +619,7 @@ encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
METHODDEF(boolean)
encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
register int temp;
register int r, k;
int EOB;
@@ -751,8 +747,7 @@ encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
METHODDEF(void)
finish_pass_phuff (j_compress_ptr cinfo)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
entropy->next_output_byte = cinfo->dest->next_output_byte;
entropy->free_in_buffer = cinfo->dest->free_in_buffer;
@@ -773,8 +768,7 @@ finish_pass_phuff (j_compress_ptr cinfo)
METHODDEF(void)
finish_pass_gather_phuff (j_compress_ptr cinfo)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) lossyc->entropy_private;
phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
boolean is_DC_band;
int ci, tbl;
jpeg_component_info * compptr;
@@ -814,13 +808,6 @@ finish_pass_gather_phuff (j_compress_ptr cinfo)
}
METHODDEF(boolean)
need_optimization_pass (j_compress_ptr cinfo)
{
return (cinfo->Ss != 0 || cinfo->Ah == 0);
}
/*
* Module initialization routine for progressive Huffman entropy encoding.
*/
@@ -828,16 +815,14 @@ need_optimization_pass (j_compress_ptr cinfo)
GLOBAL(void)
jinit_phuff_encoder (j_compress_ptr cinfo)
{
j_lossy_c_ptr lossyc = (j_lossy_c_ptr) cinfo->codec;
phuff_entropy_ptr entropy;
int i;
entropy = (phuff_entropy_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(phuff_entropy_encoder));
lossyc->entropy_private = (struct jpeg_entropy_encoder *) entropy;
lossyc->pub.entropy_start_pass = start_pass_phuff;
lossyc->pub.need_optimization_pass = need_optimization_pass;
cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
entropy->pub.start_pass = start_pass_phuff;
/* Mark tables unallocated */
for (i = 0; i < NUM_HUFF_TBLS; i++) {