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;    }  }}/* * Fast processing for the common case of 2:1 horizontal and 2:1 vertical. * It's still a box filter. */METHODDEF(void)h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr){  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;  }}/* * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical. * * The upsampling algorithm is linear interpolation between pixel centers, * also known as a "triangle filter".  This is a good compromise between * speed and visual quality.  The centers of the output pixels are 1/4 and 3/4 * of the way between input pixel centers. * * 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_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,		     JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr){  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;  }}/* * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical. * Again a triangle filter; see comments for h2v1 case, above. * * It is OK for us to reference the adjacent input rows because we demanded * context from the main buffer controller (see initialization code). */METHODDEF(void)h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,		     JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr){  JSAMPARRAY output_data = *output_data_ptr;  register JSAMPROW inptr0, inptr1, outptr;#if BITS_IN_JSAMPLE == 8  register int thiscolsum, lastcolsum, nextcolsum;#else  register INT32 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++;  }}/* * Module initialization routine for upsampling. */GLOBAL(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) (h_out_group / h_in_group);      upsample->v_expand[ci] = (UINT8) (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);    }  }}