Program, based on tjexample.c, that demonstrates how to use the TurboJPEG 3 API to capture DCT coefficients from a JPEG file, modify them, and write them to another JPEG file

tjfilterexample.c

/*
 * Copyright (C)2011-2012, 2014-2015, 2017, 2019, 2021-2024
 *           D. R. Commander.  All Rights Reserved.
 *
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 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
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 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS",
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 */

/*
 * This program, which is based on tjexample.c, demonstrates how to use the
 * TurboJPEG 3 API to capture DCT coefficients from a JPEG file, modify them,
 * and write them to another JPEG file.
 */

#ifdef _MSC_VER
#define _CRT_SECURE_NO_DEPRECATE
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#if !defined(_MSC_VER) || _MSC_VER > 1600
#include <stdint.h>
#endif
#include <turbojpeg.h>


#define THROW(action, message) { \
  printf("ERROR in line %d while %s:\n%s\n", __LINE__, action, message); \
  retval = -1;  goto bailout; \
}

#define THROW_TJ(action)  THROW(action, tj3GetErrorStr(tjInstance))

#define THROW_UNIX(action)  THROW(action, strerror(errno))


static int customInputFilter(short *coeffs, tjregion arrayRegion,
                             tjregion planeRegion, int componentIndex,
                             int transformIndex, tjtransform *transform)
{
  short **dctPlane = (short **)transform->data;

  if (dctPlane && &dctPlane[componentIndex])
    memcpy(
      &dctPlane[componentIndex][arrayRegion.y * planeRegion.w + arrayRegion.x],
      coeffs, arrayRegion.w * arrayRegion.h * sizeof(short));

  return 0;
}


static int customOutputFilter(short *coeffs, tjregion arrayRegion,
                              tjregion planeRegion, int componentIndex,
                              int transformIndex, tjtransform *transform)
{
  short **dctPlane = (short **)transform->data;

  if (dctPlane && &dctPlane[componentIndex])
    memcpy(coeffs,
      &dctPlane[componentIndex][arrayRegion.y * planeRegion.w + arrayRegion.x],
      arrayRegion.w * arrayRegion.h * sizeof(short));

  return 0;
}


int main(int argc, char **argv)
{
  int i, retval = 0;
  FILE *jpegFile = NULL;
  unsigned char *jpegBuf = NULL, *dstBuf = NULL;
  size_t jpegSize, dstSize = 0, dctBufSize = 0;
  long size;
  tjtransform xform;
  tjhandle tjInstance = NULL;
  int width, height, colorspace, subsamp;
  short *dctBuf = NULL;
  short *dctPlane[4] = { NULL, NULL, NULL, NULL };

  memset(&xform, 0, sizeof(tjtransform));

  if (argc < 3) {
    printf("\nUSAGE: %s <Input image> <Output image>\n\n", argv[0]);
    exit(1);
  }

  if ((tjInstance = tj3Init(TJINIT_TRANSFORM)) == NULL)
    THROW_TJ("creating TurboJPEG instance");

  /* Read input image from disk into memory */
  if ((jpegFile = fopen(argv[1], "rb")) == NULL)
    THROW_UNIX("opening input file");
  if (fseek(jpegFile, 0, SEEK_END) < 0 || ((size = ftell(jpegFile)) < 0) ||
      fseek(jpegFile, 0, SEEK_SET) < 0)
    THROW_UNIX("determining input file size");
  if (size == 0)
    THROW("determining input file size", "Input file contains no data");
  jpegSize = size;
  if ((jpegBuf = tj3Alloc(jpegSize)) == NULL)
    THROW_UNIX("allocating JPEG buffer");
  if (fread(jpegBuf, jpegSize, 1, jpegFile) < 1)
    THROW_UNIX("reading input file");
  fclose(jpegFile);  jpegFile = NULL;

  /* Read JPEG header */
  if (tj3DecompressHeader(tjInstance, jpegBuf, jpegSize) < 0)
    THROW_TJ("reading JPEG header");
  width = tj3Get(tjInstance, TJPARAM_JPEGWIDTH);
  height = tj3Get(tjInstance, TJPARAM_JPEGHEIGHT);
  colorspace = tj3Get(tjInstance, TJPARAM_COLORSPACE);
  if (colorspace == TJCS_YCCK || colorspace == TJCS_CMYK)
    THROW("reading JPEG header", "YCCK and CMYK JPEG images are not supported");
  if ((subsamp = tj3Get(tjInstance, TJPARAM_SUBSAMP)) < 0)
    THROW_TJ("determining the chrominance subsampling level of the JPEG image");

  /* Allocate DCT buffer */
  dctBufSize += tj3YUVPlaneSize(0, width, 0, height, subsamp);
  if (colorspace != TJCS_GRAY) {
    dctBufSize += tj3YUVPlaneSize(1, width, 0, height, subsamp);
    dctBufSize += tj3YUVPlaneSize(2, width, 0, height, subsamp);
  }
  if ((dctBuf = (short *)malloc(dctBufSize * sizeof(short))) == NULL)
    THROW_UNIX("allocating DCT buffer");
  dctPlane[0] = dctBuf;
  if (colorspace != TJCS_GRAY) {
    dctPlane[1] = &dctPlane[0][tj3YUVPlaneSize(0, width, 0, height, subsamp)];
    dctPlane[2] = &dctPlane[1][tj3YUVPlaneSize(1, width, 0, height, subsamp)];
  }

  /* First pass: copy DCT coefficients from input image into DCT buffer */
  xform.options = TJXOPT_NOOUTPUT;
  xform.customFilter = customInputFilter;
  xform.data = (void *)&dctPlane;
  if (tj3Transform(tjInstance, jpegBuf, jpegSize, 1, &dstBuf, &dstSize,
                   &xform) < 0)
    THROW_TJ("transforming input image");

  /* Negate all DCT coefficients (photo negative)

     NOTE: DCT coefficient capture isn't necessary for such a simple filter.
     We could apply this filter in a custom filter function using only one
     pass.  DCT coefficient capture is, however, necessary if you want to move
     coefficients around. */
  for (i = 0; i < dctBufSize; i++)
    dctBuf[i] = -dctBuf[i];

  /* Second pass: copy DCT coefficients from DCT buffer into output image

     NOTE: There is unnecessary overhead here, because tj3Transform() re-reads
     the input image header and performs entropy decoding on the input image
     again, even though our filter will replace the decoded coefficients. */
  xform.options = 0;
  xform.customFilter = customOutputFilter;
  if (tj3Transform(tjInstance, jpegBuf, jpegSize, 1, &dstBuf, &dstSize,
                   &xform) < 0)
    THROW_TJ("transforming input image");

  if ((jpegFile = fopen(argv[2], "wb")) == NULL)
    THROW_UNIX("opening output file");
  if (fwrite(dstBuf, dstSize, 1, jpegFile) < 1)
    THROW_UNIX("writing output file");

bailout:
  tj3Destroy(tjInstance);
  if (jpegFile) fclose(jpegFile);
  tj3Free(jpegBuf);
  free(dctBuf);
  tj3Free(dstBuf);
  return retval;
}