217d1a75f5
- 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.
104 lines
2.8 KiB
C
104 lines
2.8 KiB
C
/*
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* jlossls.h
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*
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* This file was part of the Independent JPEG Group's software:
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* Copyright (C) 1998, Thomas G. Lane.
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* Lossless JPEG Modifications:
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* Copyright (C) 1999, Ken Murchison.
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* Copyright (C) 2022, D. R. Commander.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This include file contains common declarations for the lossless JPEG
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* codec modules.
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*/
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#ifndef JLOSSLS_H
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#define JLOSSLS_H
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#if defined(C_LOSSLESS_SUPPORTED) || defined(D_LOSSLESS_SUPPORTED)
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#define JPEG_INTERNALS
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#include "jpeglib.h"
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#define ALLOC_DARRAY(pool_id, diffsperrow, numrows) \
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(JDIFFARRAY)(*cinfo->mem->alloc_sarray) \
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((j_common_ptr) cinfo, pool_id, \
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(diffsperrow) * sizeof(JDIFF) / sizeof(JSAMPLE), numrows)
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/*
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* Table H.1: Predictors for lossless coding.
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*/
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#define PREDICTOR1 Ra
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#define PREDICTOR2 Rb
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#define PREDICTOR3 Rc
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#define PREDICTOR4 (int) ((INT32) Ra + (INT32) Rb - (INT32) Rc)
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#define PREDICTOR5 (int) ((INT32) Ra + RIGHT_SHIFT((INT32) Rb - (INT32) Rc, 1))
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#define PREDICTOR6 (int) ((INT32) Rb + RIGHT_SHIFT((INT32) Ra - (INT32) Rc, 1))
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#define PREDICTOR7 (int) RIGHT_SHIFT((INT32) Ra + (INT32) Rb, 1)
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#endif
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#ifdef C_LOSSLESS_SUPPORTED
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typedef JMETHOD(void, predict_difference_method_ptr,
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(j_compress_ptr cinfo, int ci,
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JSAMPROW input_buf, JSAMPROW prev_row,
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JDIFFROW diff_buf, JDIMENSION width));
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/* Lossless compressor */
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typedef struct {
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struct jpeg_forward_dct pub; /* public fields */
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/* It is useful to allow each component to have a separate diff method. */
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predict_difference_method_ptr predict_difference[MAX_COMPONENTS];
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/* MCU rows left in the restart interval for each component */
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unsigned int restart_rows_to_go[MAX_COMPONENTS];
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/* Sample scaling */
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JMETHOD(void, scaler_scale, (j_compress_ptr cinfo,
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JSAMPROW input_buf, JSAMPROW output_buf,
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JDIMENSION width));
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} jpeg_lossless_compressor;
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typedef jpeg_lossless_compressor * lossless_comp_ptr;
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#endif /* C_LOSSLESS_SUPPORTED */
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#ifdef D_LOSSLESS_SUPPORTED
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typedef JMETHOD(void, predict_undifference_method_ptr,
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(j_decompress_ptr cinfo, int comp_index,
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JDIFFROW diff_buf, JDIFFROW prev_row,
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JDIFFROW undiff_buf, JDIMENSION width));
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/* Lossless decompressor */
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typedef struct {
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struct jpeg_inverse_dct pub; /* public fields */
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/* Prediction, undifferencing */
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JMETHOD(void, predict_process_restart, (j_decompress_ptr cinfo));
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/* It is useful to allow each component to have a separate undiff method. */
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predict_undifference_method_ptr predict_undifference[MAX_COMPONENTS];
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/* Sample scaling */
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JMETHOD(void, scaler_scale, (j_decompress_ptr cinfo,
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JDIFFROW diff_buf, JSAMPROW output_buf,
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JDIMENSION width));
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int scale_factor;
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} jpeg_lossless_decompressor;
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typedef jpeg_lossless_decompressor * lossless_decomp_ptr;
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#endif /* D_LOSSLESS_SUPPORTED */
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#endif /* JLOSSLS_H */
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