jcsample.c File Reference

#include "jinclude.h"
#include "jpeglib.h"

Include dependency graph for jcsample.c:

Go to the source code of this file.

Classes
struct	my_downsampler

Macros
#define	JPEG_INTERNALS

Typedefs
typedef my_downsampler *	my_downsample_ptr

Functions
typedef	JMETHOD (void, downsample1_ptr,(j_compress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY output_data))
	start_pass_downsample (j_compress_ptr cinfo)
	expand_right_edge (JSAMPARRAY image_data, int num_rows, JDIMENSION input_cols, JDIMENSION output_cols)
	sep_downsample (j_compress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION in_row_index, JSAMPIMAGE output_buf, JDIMENSION out_row_group_index)
	int_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY output_data)
	fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY output_data)
	h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY output_data)
	h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY output_data)
	jinit_downsampler (j_compress_ptr cinfo)

Macro Definition Documentation

JPEG_INTERNALS

#define JPEG_INTERNALS

Definition at line 48 of file jcsample.c.

Typedef Documentation

my_downsample_ptr

typedef my_downsampler* my_downsample_ptr

Definition at line 76 of file jcsample.c.

Function Documentation

expand_right_edge()

expand_right_edge	(	JSAMPARRAY	image_data,
		int	num_rows,
		JDIMENSION	input_cols,
		JDIMENSION	output_cols
	)

Definition at line 96 of file jcsample.c.

{
  register JSAMPROW ptr;
  register JSAMPLE pixval;
  register int count;
  int row;
  int numcols = (int) (output_cols - input_cols);
 
  if (numcols > 0) {
    for (row = 0; row < num_rows; row++) {
      ptr = image_data[row] + input_cols;
      pixval = ptr[-1];     /* don't need GETJSAMPLE() here */
      for (count = numcols; count > 0; count--)
    *ptr++ = pixval;
    }
  }
}

Referenced by fullsize_downsample(), h2v1_downsample(), h2v2_downsample(), and int_downsample().

fullsize_downsample()

fullsize_downsample	(	j_compress_ptr	cinfo,
		jpeg_component_info *	compptr,
		JSAMPARRAY	input_data,
		JSAMPARRAY	output_data
	)

Definition at line 199 of file jcsample.c.

{
  /* Copy the data */
  jcopy_sample_rows(input_data, 0, output_data, 0,
            cinfo->max_v_samp_factor, cinfo->image_width);
  /* Edge-expand */
  expand_right_edge(output_data, cinfo->max_v_samp_factor, cinfo->image_width,
            compptr->width_in_blocks * compptr->DCT_h_scaled_size);
}

Referenced by jinit_downsampler().

h2v1_downsample()

h2v1_downsample	(	j_compress_ptr	cinfo,
		jpeg_component_info *	compptr,
		JSAMPARRAY	input_data,
		JSAMPARRAY	output_data
	)

Definition at line 224 of file jcsample.c.

{
  int inrow;
  JDIMENSION outcol;
  JDIMENSION output_cols = compptr->width_in_blocks * compptr->DCT_h_scaled_size;
  register JSAMPROW inptr, outptr;
  register int bias;
 
  /* Expand input data enough to let all the output samples be generated
   * by the standard loop.  Special-casing padded output would be more
   * efficient.
   */
  expand_right_edge(input_data, cinfo->max_v_samp_factor,
            cinfo->image_width, output_cols * 2);
 
  for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
    outptr = output_data[inrow];
    inptr = input_data[inrow];
    bias = 0;           /* bias = 0,1,0,1,... for successive samples */
    for (outcol = 0; outcol < output_cols; outcol++) {
      *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr) + GETJSAMPLE(inptr[1])
                  + bias) >> 1);
      bias ^= 1;        /* 0=>1, 1=>0 */
      inptr += 2;
    }
  }
}

Referenced by jinit_downsampler().

h2v2_downsample()

h2v2_downsample	(	j_compress_ptr	cinfo,
		jpeg_component_info *	compptr,
		JSAMPARRAY	input_data,
		JSAMPARRAY	output_data
	)

Definition at line 261 of file jcsample.c.

{
  int inrow, outrow;
  JDIMENSION outcol;
  JDIMENSION output_cols = compptr->width_in_blocks * compptr->DCT_h_scaled_size;
  register JSAMPROW inptr0, inptr1, outptr;
  register int bias;
 
  /* Expand input data enough to let all the output samples be generated
   * by the standard loop.  Special-casing padded output would be more
   * efficient.
   */
  expand_right_edge(input_data, cinfo->max_v_samp_factor,
            cinfo->image_width, output_cols * 2);
 
  inrow = outrow = 0;
  while (inrow < cinfo->max_v_samp_factor) {
    outptr = output_data[outrow];
    inptr0 = input_data[inrow];
    inptr1 = input_data[inrow+1];
    bias = 1;           /* bias = 1,2,1,2,... for successive samples */
    for (outcol = 0; outcol < output_cols; outcol++) {
      *outptr++ = (JSAMPLE) ((GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
                  GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1])
                  + bias) >> 2);
      bias ^= 3;        /* 1=>2, 2=>1 */
      inptr0 += 2; inptr1 += 2;
    }
    inrow += 2;
    outrow++;
  }
}

Referenced by jinit_downsampler().

int_downsample()

int_downsample	(	j_compress_ptr	cinfo,
		jpeg_component_info *	compptr,
		JSAMPARRAY	input_data,
		JSAMPARRAY	output_data
	)

Definition at line 150 of file jcsample.c.

{
  my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample;
  int inrow, outrow, h_expand, v_expand, numpix, numpix2, h, v;
  JDIMENSION outcol, outcol_h;  /* outcol_h == outcol*h_expand */
  JDIMENSION output_cols = compptr->width_in_blocks * compptr->DCT_h_scaled_size;
  JSAMPROW inptr, outptr;
  INT32 outvalue;
 
  h_expand = downsample->h_expand[compptr->component_index];
  v_expand = downsample->v_expand[compptr->component_index];
  numpix = h_expand * v_expand;
  numpix2 = numpix/2;
 
  /* Expand input data enough to let all the output samples be generated
   * by the standard loop.  Special-casing padded output would be more
   * efficient.
   */
  expand_right_edge(input_data, cinfo->max_v_samp_factor,
            cinfo->image_width, output_cols * h_expand);
 
  inrow = outrow = 0;
  while (inrow < cinfo->max_v_samp_factor) {
    outptr = output_data[outrow];
    for (outcol = 0, outcol_h = 0; outcol < output_cols;
     outcol++, outcol_h += h_expand) {
      outvalue = 0;
      for (v = 0; v < v_expand; v++) {
    inptr = input_data[inrow+v] + outcol_h;
    for (h = 0; h < h_expand; h++) {
      outvalue += (INT32) GETJSAMPLE(*inptr++);
    }
      }
      *outptr++ = (JSAMPLE) ((outvalue + numpix2) / numpix);
    }
    inrow += v_expand;
    outrow++;
  }
}

Referenced by jinit_downsampler().

jinit_downsampler()

jinit_downsampler

(

j_compress_ptr

cinfo

)

Definition at line 478 of file jcsample.c.

{
  my_downsample_ptr downsample;
  int ci;
  jpeg_component_info * compptr;
  boolean smoothok = TRUE;
  int h_in_group, v_in_group, h_out_group, v_out_group;
 
  downsample = (my_downsample_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                SIZEOF(my_downsampler));
  cinfo->downsample = (struct jpeg_downsampler *) downsample;
  downsample->pub.start_pass = start_pass_downsample;
  downsample->pub.downsample = sep_downsample;
  downsample->pub.need_context_rows = FALSE;
 
  if (cinfo->CCIR601_sampling)
    ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
 
  /* Verify we can handle the sampling factors, and set up method pointers */
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Compute size of an "output group" for DCT scaling.  This many samples
     * are to be converted from max_h_samp_factor * max_v_samp_factor pixels.
     */
    h_out_group = (compptr->h_samp_factor * compptr->DCT_h_scaled_size) /
          cinfo->min_DCT_h_scaled_size;
    v_out_group = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) /
          cinfo->min_DCT_v_scaled_size;
    h_in_group = cinfo->max_h_samp_factor;
    v_in_group = cinfo->max_v_samp_factor;
    downsample->rowgroup_height[ci] = v_out_group; /* save for use later */
    if (h_in_group == h_out_group && v_in_group == v_out_group) {
#ifdef INPUT_SMOOTHING_SUPPORTED
      if (cinfo->smoothing_factor) {
    downsample->methods[ci] = fullsize_smooth_downsample;
    downsample->pub.need_context_rows = TRUE;
      } else
#endif
    downsample->methods[ci] = fullsize_downsample;
    } else if (h_in_group == h_out_group * 2 &&
           v_in_group == v_out_group) {
      smoothok = FALSE;
      downsample->methods[ci] = h2v1_downsample;
    } else if (h_in_group == h_out_group * 2 &&
           v_in_group == v_out_group * 2) {
#ifdef INPUT_SMOOTHING_SUPPORTED
      if (cinfo->smoothing_factor) {
    downsample->methods[ci] = h2v2_smooth_downsample;
    downsample->pub.need_context_rows = TRUE;
      } else
#endif
    downsample->methods[ci] = h2v2_downsample;
    } else if ((h_in_group % h_out_group) == 0 &&
           (v_in_group % v_out_group) == 0) {
      smoothok = FALSE;
      downsample->methods[ci] = int_downsample;
      downsample->h_expand[ci] = (UINT8) (h_in_group / h_out_group);
      downsample->v_expand[ci] = (UINT8) (v_in_group / v_out_group);
    } else
      ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
  }
 
#ifdef INPUT_SMOOTHING_SUPPORTED
  if (cinfo->smoothing_factor && !smoothok)
    TRACEMS(cinfo, 0, JTRC_SMOOTH_NOTIMPL);
#endif
}

Referenced by jinit_compress_master().

JMETHOD()

typedef JMETHOD	(	void	,
		downsample1_ptr	,
		(j_compress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY output_data)
	)

sep_downsample()

sep_downsample	(	j_compress_ptr	cinfo,
		JSAMPIMAGE	input_buf,
		JDIMENSION	in_row_index,
		JSAMPIMAGE	output_buf,
		JDIMENSION	out_row_group_index
	)

Definition at line 123 of file jcsample.c.

{
  my_downsample_ptr downsample = (my_downsample_ptr) cinfo->downsample;
  int ci;
  jpeg_component_info * compptr;
  JSAMPARRAY in_ptr, out_ptr;
 
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    in_ptr = input_buf[ci] + in_row_index;
    out_ptr = output_buf[ci] +
          (out_row_group_index * downsample->rowgroup_height[ci]);
    (*downsample->methods[ci]) (cinfo, compptr, in_ptr, out_ptr);
  }
}

Referenced by jinit_downsampler().

start_pass_downsample()

start_pass_downsample

(

j_compress_ptr

cinfo

)

Definition at line 84 of file jcsample.c.

{
  /* no work for now */
}

Referenced by jinit_downsampler().