diff options
Diffstat (limited to 'plugins/FreeImage/Source/LibJPEG/jcsample.c')
| -rw-r--r-- | plugins/FreeImage/Source/LibJPEG/jcsample.c | 545 | 
1 files changed, 545 insertions, 0 deletions
diff --git a/plugins/FreeImage/Source/LibJPEG/jcsample.c b/plugins/FreeImage/Source/LibJPEG/jcsample.c new file mode 100644 index 0000000000..1aef8a6fc7 --- /dev/null +++ b/plugins/FreeImage/Source/LibJPEG/jcsample.c @@ -0,0 +1,545 @@ +/*
 + * jcsample.c
 + *
 + * Copyright (C) 1991-1996, 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 downsampling routines.
 + *
 + * Downsampling input data is counted in "row groups".  A row group
 + * is defined to be max_v_samp_factor pixel rows of each component,
 + * from which the downsampler produces v_samp_factor sample rows.
 + * A single row group is processed in each call to the downsampler module.
 + *
 + * The downsampler is responsible for edge-expansion of its output data
 + * to fill an integral number of DCT blocks horizontally.  The source buffer
 + * may be modified if it is helpful for this purpose (the source buffer is
 + * allocated wide enough to correspond to the desired output width).
 + * The caller (the prep controller) is responsible for vertical padding.
 + *
 + * The downsampler may request "context rows" by setting need_context_rows
 + * during startup.  In this case, the input arrays will contain at least
 + * one row group's worth of pixels above and below the passed-in data;
 + * the caller will create dummy rows at image top and bottom by replicating
 + * the first or last real pixel row.
 + *
 + * An excellent reference for image resampling is
 + *   Digital Image Warping, George Wolberg, 1990.
 + *   Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
 + *
 + * The downsampling algorithm used here is a simple average of the source
 + * pixels covered by the output pixel.  The hi-falutin sampling literature
 + * refers to this as a "box filter".  In general the characteristics of a box
 + * filter are not very good, but for the specific cases we normally use (1:1
 + * and 2:1 ratios) the box is equivalent to a "triangle filter" which is not
 + * nearly so bad.  If you intend to use other sampling ratios, you'd be well
 + * advised to improve this code.
 + *
 + * A simple input-smoothing capability is provided.  This is mainly intended
 + * for cleaning up color-dithered GIF input files (if you find it inadequate,
 + * we suggest using an external filtering program such as pnmconvol).  When
 + * enabled, each input pixel P is replaced by a weighted sum of itself and its
 + * eight neighbors.  P's weight is 1-8*SF and each neighbor's weight is SF,
 + * where SF = (smoothing_factor / 1024).
 + * Currently, smoothing is only supported for 2h2v sampling factors.
 + */
 +
 +#define JPEG_INTERNALS
 +#include "jinclude.h"
 +#include "jpeglib.h"
 +
 +
 +/* Pointer to routine to downsample a single component */
 +typedef JMETHOD(void, downsample1_ptr,
 +		(j_compress_ptr cinfo, jpeg_component_info * compptr,
 +		 JSAMPARRAY input_data, JSAMPARRAY output_data));
 +
 +/* Private subobject */
 +
 +typedef struct {
 +  struct jpeg_downsampler pub;	/* public fields */
 +
 +  /* Downsampling method pointers, one per component */
 +  downsample1_ptr methods[MAX_COMPONENTS];
 +
 +  /* Height of an output row group for each component. */
 +  int rowgroup_height[MAX_COMPONENTS];
 +
 +  /* These arrays save pixel expansion factors so that int_downsample need not
 +   * recompute them each time.  They are unused for other downsampling methods.
 +   */
 +  UINT8 h_expand[MAX_COMPONENTS];
 +  UINT8 v_expand[MAX_COMPONENTS];
 +} my_downsampler;
 +
 +typedef my_downsampler * my_downsample_ptr;
 +
 +
 +/*
 + * Initialize for a downsampling pass.
 + */
 +
 +METHODDEF(void)
 +start_pass_downsample (j_compress_ptr cinfo)
 +{
 +  /* no work for now */
 +}
 +
 +
 +/*
 + * Expand a component horizontally from width input_cols to width output_cols,
 + * by duplicating the rightmost samples.
 + */
 +
 +LOCAL(void)
 +expand_right_edge (JSAMPARRAY image_data, int num_rows,
 +		   JDIMENSION input_cols, JDIMENSION output_cols)
 +{
 +  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;
 +    }
 +  }
 +}
 +
 +
 +/*
 + * Do downsampling for a whole row group (all components).
 + *
 + * In this version we simply downsample each component independently.
 + */
 +
 +METHODDEF(void)
 +sep_downsample (j_compress_ptr cinfo,
 +		JSAMPIMAGE input_buf, JDIMENSION in_row_index,
 +		JSAMPIMAGE output_buf, JDIMENSION out_row_group_index)
 +{
 +  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);
 +  }
 +}
 +
 +
 +/*
 + * Downsample pixel values of a single component.
 + * One row group is processed per call.
 + * This version handles arbitrary integral sampling ratios, without smoothing.
 + * Note that this version is not actually used for customary sampling ratios.
 + */
 +
 +METHODDEF(void)
 +int_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
 +		JSAMPARRAY input_data, JSAMPARRAY output_data)
 +{
 +  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++;
 +  }
 +}
 +
 +
 +/*
 + * Downsample pixel values of a single component.
 + * This version handles the special case of a full-size component,
 + * without smoothing.
 + */
 +
 +METHODDEF(void)
 +fullsize_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
 +		     JSAMPARRAY input_data, JSAMPARRAY output_data)
 +{
 +  /* 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);
 +}
 +
 +
 +/*
 + * Downsample pixel values of a single component.
 + * This version handles the common case of 2:1 horizontal and 1:1 vertical,
 + * without smoothing.
 + *
 + * A note about the "bias" calculations: when rounding fractional values to
 + * integer, we do not want to always round 0.5 up to the next integer.
 + * If we did that, we'd introduce a noticeable bias towards larger values.
 + * Instead, this code is arranged so that 0.5 will be rounded up or down at
 + * alternate pixel locations (a simple ordered dither pattern).
 + */
 +
 +METHODDEF(void)
 +h2v1_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
 +		 JSAMPARRAY input_data, JSAMPARRAY output_data)
 +{
 +  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;
 +    }
 +  }
 +}
 +
 +
 +/*
 + * Downsample pixel values of a single component.
 + * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
 + * without smoothing.
 + */
 +
 +METHODDEF(void)
 +h2v2_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
 +		 JSAMPARRAY input_data, JSAMPARRAY output_data)
 +{
 +  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++;
 +  }
 +}
 +
 +
 +#ifdef INPUT_SMOOTHING_SUPPORTED
 +
 +/*
 + * Downsample pixel values of a single component.
 + * This version handles the standard case of 2:1 horizontal and 2:1 vertical,
 + * with smoothing.  One row of context is required.
 + */
 +
 +METHODDEF(void)
 +h2v2_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info * compptr,
 +			JSAMPARRAY input_data, JSAMPARRAY output_data)
 +{
 +  int inrow, outrow;
 +  JDIMENSION colctr;
 +  JDIMENSION output_cols = compptr->width_in_blocks * compptr->DCT_h_scaled_size;
 +  register JSAMPROW inptr0, inptr1, above_ptr, below_ptr, outptr;
 +  INT32 membersum, neighsum, memberscale, neighscale;
 +
 +  /* 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 - 1, cinfo->max_v_samp_factor + 2,
 +		    cinfo->image_width, output_cols * 2);
 +
 +  /* We don't bother to form the individual "smoothed" input pixel values;
 +   * we can directly compute the output which is the average of the four
 +   * smoothed values.  Each of the four member pixels contributes a fraction
 +   * (1-8*SF) to its own smoothed image and a fraction SF to each of the three
 +   * other smoothed pixels, therefore a total fraction (1-5*SF)/4 to the final
 +   * output.  The four corner-adjacent neighbor pixels contribute a fraction
 +   * SF to just one smoothed pixel, or SF/4 to the final output; while the
 +   * eight edge-adjacent neighbors contribute SF to each of two smoothed
 +   * pixels, or SF/2 overall.  In order to use integer arithmetic, these
 +   * factors are scaled by 2^16 = 65536.
 +   * Also recall that SF = smoothing_factor / 1024.
 +   */
 +
 +  memberscale = 16384 - cinfo->smoothing_factor * 80; /* scaled (1-5*SF)/4 */
 +  neighscale = cinfo->smoothing_factor * 16; /* scaled SF/4 */
 +
 +  inrow = outrow = 0;
 +  while (inrow < cinfo->max_v_samp_factor) {
 +    outptr = output_data[outrow];
 +    inptr0 = input_data[inrow];
 +    inptr1 = input_data[inrow+1];
 +    above_ptr = input_data[inrow-1];
 +    below_ptr = input_data[inrow+2];
 +
 +    /* Special case for first column: pretend column -1 is same as column 0 */
 +    membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
 +		GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
 +    neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
 +	       GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
 +	       GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[2]) +
 +	       GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[2]);
 +    neighsum += neighsum;
 +    neighsum += GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[2]) +
 +		GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[2]);
 +    membersum = membersum * memberscale + neighsum * neighscale;
 +    *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
 +    inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
 +
 +    for (colctr = output_cols - 2; colctr > 0; colctr--) {
 +      /* sum of pixels directly mapped to this output element */
 +      membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
 +		  GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
 +      /* sum of edge-neighbor pixels */
 +      neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
 +		 GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
 +		 GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[2]) +
 +		 GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[2]);
 +      /* The edge-neighbors count twice as much as corner-neighbors */
 +      neighsum += neighsum;
 +      /* Add in the corner-neighbors */
 +      neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[2]) +
 +		  GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[2]);
 +      /* form final output scaled up by 2^16 */
 +      membersum = membersum * memberscale + neighsum * neighscale;
 +      /* round, descale and output it */
 +      *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
 +      inptr0 += 2; inptr1 += 2; above_ptr += 2; below_ptr += 2;
 +    }
 +
 +    /* Special case for last column */
 +    membersum = GETJSAMPLE(*inptr0) + GETJSAMPLE(inptr0[1]) +
 +		GETJSAMPLE(*inptr1) + GETJSAMPLE(inptr1[1]);
 +    neighsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(above_ptr[1]) +
 +	       GETJSAMPLE(*below_ptr) + GETJSAMPLE(below_ptr[1]) +
 +	       GETJSAMPLE(inptr0[-1]) + GETJSAMPLE(inptr0[1]) +
 +	       GETJSAMPLE(inptr1[-1]) + GETJSAMPLE(inptr1[1]);
 +    neighsum += neighsum;
 +    neighsum += GETJSAMPLE(above_ptr[-1]) + GETJSAMPLE(above_ptr[1]) +
 +		GETJSAMPLE(below_ptr[-1]) + GETJSAMPLE(below_ptr[1]);
 +    membersum = membersum * memberscale + neighsum * neighscale;
 +    *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
 +
 +    inrow += 2;
 +    outrow++;
 +  }
 +}
 +
 +
 +/*
 + * Downsample pixel values of a single component.
 + * This version handles the special case of a full-size component,
 + * with smoothing.  One row of context is required.
 + */
 +
 +METHODDEF(void)
 +fullsize_smooth_downsample (j_compress_ptr cinfo, jpeg_component_info *compptr,
 +			    JSAMPARRAY input_data, JSAMPARRAY output_data)
 +{
 +  int inrow;
 +  JDIMENSION colctr;
 +  JDIMENSION output_cols = compptr->width_in_blocks * compptr->DCT_h_scaled_size;
 +  register JSAMPROW inptr, above_ptr, below_ptr, outptr;
 +  INT32 membersum, neighsum, memberscale, neighscale;
 +  int colsum, lastcolsum, nextcolsum;
 +
 +  /* 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 - 1, cinfo->max_v_samp_factor + 2,
 +		    cinfo->image_width, output_cols);
 +
 +  /* Each of the eight neighbor pixels contributes a fraction SF to the
 +   * smoothed pixel, while the main pixel contributes (1-8*SF).  In order
 +   * to use integer arithmetic, these factors are multiplied by 2^16 = 65536.
 +   * Also recall that SF = smoothing_factor / 1024.
 +   */
 +
 +  memberscale = 65536L - cinfo->smoothing_factor * 512L; /* scaled 1-8*SF */
 +  neighscale = cinfo->smoothing_factor * 64; /* scaled SF */
 +
 +  for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
 +    outptr = output_data[inrow];
 +    inptr = input_data[inrow];
 +    above_ptr = input_data[inrow-1];
 +    below_ptr = input_data[inrow+1];
 +
 +    /* Special case for first column */
 +    colsum = GETJSAMPLE(*above_ptr++) + GETJSAMPLE(*below_ptr++) +
 +	     GETJSAMPLE(*inptr);
 +    membersum = GETJSAMPLE(*inptr++);
 +    nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
 +		 GETJSAMPLE(*inptr);
 +    neighsum = colsum + (colsum - membersum) + nextcolsum;
 +    membersum = membersum * memberscale + neighsum * neighscale;
 +    *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
 +    lastcolsum = colsum; colsum = nextcolsum;
 +
 +    for (colctr = output_cols - 2; colctr > 0; colctr--) {
 +      membersum = GETJSAMPLE(*inptr++);
 +      above_ptr++; below_ptr++;
 +      nextcolsum = GETJSAMPLE(*above_ptr) + GETJSAMPLE(*below_ptr) +
 +		   GETJSAMPLE(*inptr);
 +      neighsum = lastcolsum + (colsum - membersum) + nextcolsum;
 +      membersum = membersum * memberscale + neighsum * neighscale;
 +      *outptr++ = (JSAMPLE) ((membersum + 32768) >> 16);
 +      lastcolsum = colsum; colsum = nextcolsum;
 +    }
 +
 +    /* Special case for last column */
 +    membersum = GETJSAMPLE(*inptr);
 +    neighsum = lastcolsum + (colsum - membersum) + colsum;
 +    membersum = membersum * memberscale + neighsum * neighscale;
 +    *outptr = (JSAMPLE) ((membersum + 32768) >> 16);
 +
 +  }
 +}
 +
 +#endif /* INPUT_SMOOTHING_SUPPORTED */
 +
 +
 +/*
 + * Module initialization routine for downsampling.
 + * Note that we must select a routine for each component.
 + */
 +
 +GLOBAL(void)
 +jinit_downsampler (j_compress_ptr cinfo)
 +{
 +  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
 +}
  | 
