jdsample.cpp File Reference

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

Include dependency graph for jdsample.cpp:

Classes
struct	my_upsampler

Macros
#define	JPEG_INTERNALS

Typedefs
typedef void(*	upsample1_ptr) (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
typedef my_upsampler *	my_upsample_ptr

Functions
static void	start_pass_upsample (j_decompress_ptr cinfo)
static void	sep_upsample (j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail, JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)
static void	fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
static void	noop_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
static void	int_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
static void	h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
static void	h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
static void	h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
static void	h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
void	jinit_upsampler (j_decompress_ptr cinfo)

Macro Definition Documentation

#define JPEG_INTERNALS

Typedef Documentation

typedef void(* upsample1_ptr) (j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)

typedef my_upsampler* my_upsample_ptr

Function Documentation

static void start_pass_upsample ( j_decompress_ptr  cinfo )

static

{
  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;

  /* Mark the conversion buffer empty */
  upsample->next_row_out = cinfo->max_v_samp_factor;
  /* Initialize total-height counter for detecting bottom of image */
  upsample->rows_to_go = cinfo->output_height;
}

static void sep_upsample ( j_decompress_ptr  cinfo, JSAMPIMAGE  input_buf, JDIMENSION *  in_row_group_ctr, JDIMENSION  in_row_groups_avail, JSAMPARRAY  output_buf, JDIMENSION *  out_row_ctr, JDIMENSION  out_rows_avail  )

static

{
  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
  int ci;
  jpeg_component_info * compptr;
  JDIMENSION num_rows;

  /* Fill the conversion buffer, if it's empty */
  if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
     ci++, compptr++) {
      /* Invoke per-component upsample method.  Notice we pass a POINTER
       * to color_buf[ci], so that fullsize_upsample can change it.
       */
      (*upsample->methods[ci]) (cinfo, compptr,
    input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
    upsample->color_buf + ci);
    }
    upsample->next_row_out = 0;
  }

  /* Color-convert and emit rows */

  /* How many we have in the buffer: */
  num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
  /* Not more than the distance to the end of the image.  Need this test
   * in case the image height is not a multiple of max_v_samp_factor:
   */
  if (num_rows > upsample->rows_to_go) 
    num_rows = upsample->rows_to_go;
  /* And not more than what the client can accept: */
  out_rows_avail -= *out_row_ctr;
  if (num_rows > out_rows_avail)
    num_rows = out_rows_avail;

  (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
                     (JDIMENSION) upsample->next_row_out,
                     output_buf + *out_row_ctr,
                     (int) num_rows);

  /* Adjust counts */
  *out_row_ctr += num_rows;
  upsample->rows_to_go -= num_rows;
  upsample->next_row_out += num_rows;
  /* When the buffer is emptied, declare this input row group consumed */
  if (upsample->next_row_out >= cinfo->max_v_samp_factor)
    (*in_row_group_ctr)++;
}

static void fullsize_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  *output_data_ptr = input_data;
}

static void noop_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  *output_data_ptr = NULL;  /* safety check */
}

static void int_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
  JSAMPARRAY output_data = *output_data_ptr;
  register JSAMPROW inptr, outptr;
  register JSAMPLE invalue;
  register int h;
  JSAMPROW outend;
  int h_expand, v_expand;
  int inrow, outrow;

  h_expand = upsample->h_expand[compptr->component_index];
  v_expand = upsample->v_expand[compptr->component_index];

  inrow = outrow = 0;
  while (outrow < cinfo->max_v_samp_factor) {
    /* Generate one output row with proper horizontal expansion */
    inptr = input_data[inrow];
    outptr = output_data[outrow];
    outend = outptr + cinfo->output_width;
    while (outptr < outend) {
      invalue = *inptr++;   /* don't need GETJSAMPLE() here */
      for (h = h_expand; h > 0; h--) {
    *outptr++ = invalue;
      }
    }
    /* Generate any additional output rows by duplicating the first one */
    if (v_expand > 1) {
      jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
            v_expand-1, cinfo->output_width);
    }
    inrow++;
    outrow += v_expand;
  }
}

static void h2v1_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  JSAMPARRAY output_data = *output_data_ptr;
  register JSAMPROW inptr, outptr;
  register JSAMPLE invalue;
  JSAMPROW outend;
  int inrow;

  for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
    inptr = input_data[inrow];
    outptr = output_data[inrow];
    outend = outptr + cinfo->output_width;
    while (outptr < outend) {
      invalue = *inptr++;   /* don't need GETJSAMPLE() here */
      *outptr++ = invalue;
      *outptr++ = invalue;
    }
  }
}

static void h2v2_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  JSAMPARRAY output_data = *output_data_ptr;
  register JSAMPROW inptr, outptr;
  register JSAMPLE invalue;
  JSAMPROW outend;
  int inrow, outrow;

  inrow = outrow = 0;
  while (outrow < cinfo->max_v_samp_factor) {
    inptr = input_data[inrow];
    outptr = output_data[outrow];
    outend = outptr + cinfo->output_width;
    while (outptr < outend) {
      invalue = *inptr++;   /* don't need GETJSAMPLE() here */
      *outptr++ = invalue;
      *outptr++ = invalue;
    }
    jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
              1, cinfo->output_width);
    inrow++;
    outrow += 2;
  }
}

static void h2v1_fancy_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  JSAMPARRAY output_data = *output_data_ptr;
  register JSAMPROW inptr, outptr;
  register int invalue;
  register JDIMENSION colctr;
  int inrow;

  for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
    inptr = input_data[inrow];
    outptr = output_data[inrow];
    /* Special case for first column */
    invalue = GETJSAMPLE(*inptr++);
    *outptr++ = (JSAMPLE) invalue;
    *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);

    for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
      /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
      invalue = GETJSAMPLE(*inptr++) * 3;
      *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
      *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
    }

    /* Special case for last column */
    invalue = GETJSAMPLE(*inptr);
    *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
    *outptr++ = (JSAMPLE) invalue;
  }
}

static void h2v2_fancy_upsample ( j_decompress_ptr  cinfo, jpeg_component_info *  compptr, JSAMPARRAY  input_data, JSAMPARRAY *  output_data_ptr  )

static

{
  JSAMPARRAY output_data = *output_data_ptr;
  register JSAMPROW inptr0, inptr1, outptr;
#if BITS_IN_JSAMPLE == 8
  register int thiscolsum, lastcolsum, nextcolsum;
#else
  register int32_t thiscolsum, lastcolsum, nextcolsum;
#endif
  register JDIMENSION colctr;
  int inrow, outrow, v;

  inrow = outrow = 0;
  while (outrow < cinfo->max_v_samp_factor) {
    for (v = 0; v < 2; v++) {
      /* inptr0 points to nearest input row, inptr1 points to next nearest */
      inptr0 = input_data[inrow];
      if (v == 0)       /* next nearest is row above */
    inptr1 = input_data[inrow-1];
      else          /* next nearest is row below */
    inptr1 = input_data[inrow+1];
      outptr = output_data[outrow++];

      /* Special case for first column */
      thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
      nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
      *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
      *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
      lastcolsum = thiscolsum; thiscolsum = nextcolsum;

      for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
    /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
    /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
    nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
    *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
    *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
    lastcolsum = thiscolsum; thiscolsum = nextcolsum;
      }

      /* Special case for last column */
      *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
      *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
    }
    inrow++;
  }
}

void jinit_upsampler

(

j_decompress_ptr

cinfo

)

{
  my_upsample_ptr upsample;
  int ci;
  jpeg_component_info * compptr;
  boolean need_buffer, do_fancy;
  int h_in_group, v_in_group, h_out_group, v_out_group;

  upsample = (my_upsample_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                SIZEOF(my_upsampler));
  cinfo->upsample = (struct jpeg_upsampler *) upsample;
  upsample->pub.start_pass = start_pass_upsample;
  upsample->pub.upsample = sep_upsample;
  upsample->pub.need_context_rows = FALSE; /* until we find out differently */

  if (cinfo->CCIR601_sampling)  /* this isn't supported */
    ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);

  /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
   * so don't ask for it.
   */
  do_fancy = cinfo->do_fancy_upsampling && cinfo->min_DCT_scaled_size > 1;

  /* Verify we can handle the sampling factors, select per-component methods,
   * and create storage as needed.
   */
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Compute size of an "input group" after IDCT scaling.  This many samples
     * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
     */
    h_in_group = (compptr->h_samp_factor * compptr->DCT_scaled_size) /
         cinfo->min_DCT_scaled_size;
    v_in_group = (compptr->v_samp_factor * compptr->DCT_scaled_size) /
         cinfo->min_DCT_scaled_size;
    h_out_group = cinfo->max_h_samp_factor;
    v_out_group = cinfo->max_v_samp_factor;
    upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
    need_buffer = TRUE;
    if (! compptr->component_needed) {
      /* Don't bother to upsample an uninteresting component. */
      upsample->methods[ci] = noop_upsample;
      need_buffer = FALSE;
    } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
      /* Fullsize components can be processed without any work. */
      upsample->methods[ci] = fullsize_upsample;
      need_buffer = FALSE;
    } else if (h_in_group * 2 == h_out_group &&
           v_in_group == v_out_group) {
      /* Special cases for 2h1v upsampling */
      if (do_fancy && compptr->downsampled_width > 2)
    upsample->methods[ci] = h2v1_fancy_upsample;
      else
    upsample->methods[ci] = h2v1_upsample;
    } else if (h_in_group * 2 == h_out_group &&
           v_in_group * 2 == v_out_group) {
      /* Special cases for 2h2v upsampling */
      if (do_fancy && compptr->downsampled_width > 2) {
    upsample->methods[ci] = h2v2_fancy_upsample;
    upsample->pub.need_context_rows = TRUE;
      } else
    upsample->methods[ci] = h2v2_upsample;
    } else if ((h_out_group % h_in_group) == 0 &&
           (v_out_group % v_in_group) == 0) {
      /* Generic integral-factors upsampling method */
      upsample->methods[ci] = int_upsample;
      upsample->h_expand[ci] = (uint8_t) (h_out_group / h_in_group);
      upsample->v_expand[ci] = (uint8_t) (v_out_group / v_in_group);
    } else
      ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
    if (need_buffer) {
      upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
    ((j_common_ptr) cinfo, JPOOL_IMAGE,
     (JDIMENSION) jround_up((long) cinfo->output_width,
                (long) cinfo->max_h_samp_factor),
     (JDIMENSION) cinfo->max_v_samp_factor);
    }
  }
}