kc3-lang/libjpeg-turbo/jdcoefct.h

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• Hash : 6d91e950
  Author :
  Date : 2020-10-05T13:37:44
  

  Use 5x5 win & 9 AC coeffs when smoothing DC scans
  
  ... of progressive images.
  
  Based on:
  https://github.com/mo271/libjpeg-turbo/commit/be8d36d13b79a472e56da0717ba067e6139bc0e1
  https://github.com/mo271/libjpeg-turbo/commit/9d528f278ee3a5ba571c0b9ec4567c557614fb25
  https://github.com/mo271/libjpeg-turbo/commit/85f36f0765ea2c28909fc4c0e570cd68d3a1ed85
  https://github.com/mo271/libjpeg-turbo/commit/63a4d39e387f61bcb83b393838f436b410b97308
  https://github.com/mo271/libjpeg-turbo/commit/51336a6ad5acb9379dc8e3e5e5758fd439224b7c
  
  Closes #459
  Closes #474
  

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• jdcoefct.h

• /*
   * jdcoefct.h
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1994-1997, Thomas G. Lane.
   * libjpeg-turbo Modifications:
   * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
   * Copyright (C) 2020, Google, Inc.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   */
  
  #define JPEG_INTERNALS
  #include "jpeglib.h"
  
  
  /* Block smoothing is only applicable for progressive JPEG, so: */
  #ifndef D_PROGRESSIVE_SUPPORTED
  #undef BLOCK_SMOOTHING_SUPPORTED
  #endif
  
  
  /* Private buffer controller object */
  
  typedef struct {
    struct jpeg_d_coef_controller pub; /* public fields */
  
    /* These variables keep track of the current location of the input side. */
    /* cinfo->input_iMCU_row is also used for this. */
    JDIMENSION MCU_ctr;           /* counts MCUs processed in current row */
    int MCU_vert_offset;          /* counts MCU rows within iMCU row */
    int MCU_rows_per_iMCU_row;    /* number of such rows needed */
  
    /* The output side's location is represented by cinfo->output_iMCU_row. */
  
    /* In single-pass modes, it's sufficient to buffer just one MCU.
     * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
     * and let the entropy decoder write into that workspace each time.
     * In multi-pass modes, this array points to the current MCU's blocks
     * within the virtual arrays; it is used only by the input side.
     */
    JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
  
    /* Temporary workspace for one MCU */
    JCOEF *workspace;
  
  #ifdef D_MULTISCAN_FILES_SUPPORTED
    /* In multi-pass modes, we need a virtual block array for each component. */
    jvirt_barray_ptr whole_image[MAX_COMPONENTS];
  #endif
  
  #ifdef BLOCK_SMOOTHING_SUPPORTED
    /* When doing block smoothing, we latch coefficient Al values here */
    int *coef_bits_latch;
  #define SAVED_COEFS  10         /* we save coef_bits[0..9] */
  #endif
  } my_coef_controller;
  
  typedef my_coef_controller *my_coef_ptr;
  
  
  LOCAL(void)
  start_iMCU_row(j_decompress_ptr cinfo)
  /* Reset within-iMCU-row counters for a new row (input side) */
  {
    my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
  
    /* In an interleaved scan, an MCU row is the same as an iMCU row.
     * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
     * But at the bottom of the image, process only what's left.
     */
    if (cinfo->comps_in_scan > 1) {
      coef->MCU_rows_per_iMCU_row = 1;
    } else {
      if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows - 1))
        coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
      else
        coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
    }
  
    coef->MCU_ctr = 0;
    coef->MCU_vert_offset = 0;
  }
  

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