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b897766a7a
Both JPEG decoders ignored the DC/AC table selectors in the SOS header and always decoded luma with tables 0 and chroma with tables 1, the layout libjpeg writes by default. Files where all components share table 0, or where the slots are assigned differently, decoded to noise. Look up each component's tables from its selectors instead. Baseline JPEG only allows tables 0 and 1, which both decoders already hold, so this needs no extra memory; selectors above 1 are rejected. In the core loader tab_membership is no longer used and is removed. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Change-Id: Ie1ec407ddecf1256fef410b1256b97af412fb194
75 lines
2.9 KiB
C
75 lines
2.9 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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*
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* JPEG image viewer
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* (This is a real mess if it has to be coded in one single C file)
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*
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* File scrolling addition (C) 2005 Alexander Spyridakis
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* Copyright (C) 2004 Jörg Hohensohn aka [IDC]Dragon
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* Heavily borrowed from the IJG implementation (C) Thomas G. Lane
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* Small & fast downscaling IDCT (C) 2002 by Guido Vollbeding JPEGclub.org
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef _JPEG_JPEG_DECODER_H
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#define _JPEG_JPEG_DECODER_H
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#include "jpeg_common.h"
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struct jpeg
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{
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int x_size, y_size; /* size of image (can be less than block boundary) */
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int x_phys, y_phys; /* physical size, block aligned */
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int x_mbl; /* x dimension of MBL */
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int y_mbl; /* y dimension of MBL */
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int blocks; /* blocks per MB */
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int restart_interval; /* number of MCUs between RSTm markers */
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int store_pos[4]; /* for Y block ordering */
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unsigned char* p_entropy_data;
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unsigned char* p_entropy_end;
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int quanttable[4][QUANT_TABLE_LENGTH]; /* raw quantization tables 0-3 */
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int qt_idct[2][QUANT_TABLE_LENGTH]; /* quantization tables for IDCT */
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struct huffman_table hufftable[2]; /* Huffman tables */
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struct derived_tbl dc_derived_tbls[2]; /* Huffman-LUTs */
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struct derived_tbl ac_derived_tbls[2];
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struct frame_component frameheader[3]; /* Component descriptor */
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struct scan_component scanheader[3]; /* Huffman tables per component */
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int mcu_membership[6]; /* info per block */
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int tab_membership[6];
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int subsample_x[3]; /* info per component */
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int subsample_y[3];
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};
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/* various helper functions */
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void default_huff_tbl(struct jpeg* p_jpeg);
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void build_lut(struct jpeg* p_jpeg);
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int process_markers(unsigned char* p_src, long size, struct jpeg* p_jpeg);
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/* the main decode function */
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#ifdef HAVE_LCD_COLOR
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int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[3],
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int downscale, void (*pf_progress)(int current, int total));
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#else
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int jpeg_decode(struct jpeg* p_jpeg, unsigned char* p_pixel[1], int downscale,
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void (*pf_progress)(int current, int total));
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#endif
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#endif /* _JPEG_JPEG_DECODER_H */
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