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Diffstat (limited to 'plugins/FreeImage/src/LibJPEG/jcsample.c')
| -rw-r--r-- | plugins/FreeImage/src/LibJPEG/jcsample.c | 545 | 
1 files changed, 545 insertions, 0 deletions
diff --git a/plugins/FreeImage/src/LibJPEG/jcsample.c b/plugins/FreeImage/src/LibJPEG/jcsample.c new file mode 100644 index 0000000000..4d36f85f35 --- /dev/null +++ b/plugins/FreeImage/src/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 +}  | 
