kc3-lang/libjpeg-turbo/jcscale.c

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• Hash : 2e8360e0
  Author :
  Date : 1999-04-27T00:00:00
  

  IJG's JPEG software v6b with lossless JPEG support
  
  Patch obtained from:
  https://sourceforge.net/projects/jpeg/files/ftp.oceana.com
  
  Author date taken from original announcement and timestamp of patch
  tarball:
  https://groups.google.com/g/comp.protocols.dicom/c/rrkP8BxoMRk/m/Ij4dfprggp8J
  

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• jcscale.c

• /*
   * jcscale.c
   *
   * Copyright (C) 1998, Thomas G. Lane.
   * This file is part of the Independent JPEG Group's software.
   * For conditions of distribution and use, see the accompanying README file.
   *
   * This file contains sample downscaling by 2^Pt for lossless JPEG.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  #include "jlossls.h"		/* Private declarations for lossless codec */
  
  
  #ifdef C_LOSSLESS_SUPPORTED
  
  METHODDEF(void)
  simple_downscale(j_compress_ptr cinfo,
  		 JSAMPROW input_buf, JSAMPROW output_buf, JDIMENSION width)
  {
    j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
    int xindex;
  
    for (xindex = 0; xindex < width; xindex++)
      output_buf[xindex] = (JSAMPLE) RIGHT_SHIFT(GETJSAMPLE(input_buf[xindex]),
  					       cinfo->Al);
  }
  
  
  METHODDEF(void)
  noscale(j_compress_ptr cinfo,
  	JSAMPROW input_buf, JSAMPROW output_buf, JDIMENSION width)
  {
    MEMCOPY(output_buf, input_buf, width * SIZEOF(JSAMPLE));
    return;
  }
  
  
  METHODDEF(void)
  scaler_start_pass (j_compress_ptr cinfo)
  {
    j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
  
    /* Set scaler function based on Pt */
    if (cinfo->Al)
      losslsc->scaler_scale = simple_downscale;
    else
      losslsc->scaler_scale = noscale;
  }
  
  
  GLOBAL(void)
  jinit_c_scaler (j_compress_ptr cinfo)
  {
    j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
  
    losslsc->scaler_start_pass = scaler_start_pass;
  }
  
  #endif /* C_LOSSLESS_SUPPORTED */
  

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