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62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
/*
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* jcscale.c
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*
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* Copyright (C) 1998, Thomas G. Lane.
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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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* This file contains sample downscaling by 2^Pt for lossless JPEG.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include "jlossls.h" /* Private declarations for lossless codec */
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#ifdef C_LOSSLESS_SUPPORTED
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METHODDEF(void)
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simple_downscale(j_compress_ptr cinfo,
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JSAMPROW input_buf, JSAMPROW output_buf, JDIMENSION width)
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{
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// j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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unsigned xindex;
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for (xindex = 0; xindex < width; xindex++)
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output_buf[xindex] = (JSAMPLE) RIGHT_SHIFT(GETJSAMPLE(input_buf[xindex]),
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cinfo->Al);
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}
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METHODDEF(void)
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noscale(j_compress_ptr cinfo,
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JSAMPROW input_buf, JSAMPROW output_buf, JDIMENSION width)
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{
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MEMCOPY(output_buf, input_buf, width * SIZEOF(JSAMPLE));
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return;
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}
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METHODDEF(void)
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scaler_start_pass (j_compress_ptr cinfo)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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/* Set scaler function based on Pt */
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if (cinfo->Al)
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losslsc->scaler_scale = simple_downscale;
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else
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losslsc->scaler_scale = noscale;
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}
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GLOBAL(void)
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jinit_c_scaler (j_compress_ptr cinfo)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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losslsc->scaler_start_pass = scaler_start_pass;
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}
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#endif /* C_LOSSLESS_SUPPORTED */
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