* jdsample.c
*
* Copyright (C) 1991-1996, Thomas G. Lane.
+ * Modified 2002-2008 by Guido Vollbeding.
* 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 upsampling routines.
*
* Upsampling input data is counted in "row groups". A row group
- * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
+ * is defined to be (v_samp_factor * DCT_v_scaled_size / min_DCT_v_scaled_size)
* sample rows of each component. Upsampling will normally produce
* max_v_samp_factor pixel rows from each row group (but this could vary
* if the upsampler is applying a scale factor of its own).
register JSAMPROW inptr, outptr;
register JSAMPLE invalue;
JSAMPROW outend;
- int inrow;
+ int outrow;
- for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
- inptr = input_data[inrow];
- outptr = output_data[inrow];
+ for (outrow = 0; outrow < cinfo->max_v_samp_factor; outrow++) {
+ inptr = input_data[outrow];
+ outptr = output_data[outrow];
outend = outptr + cinfo->output_width;
while (outptr < outend) {
invalue = *inptr++; /* don't need GETJSAMPLE() here */
/*
- * 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.
*/
my_upsample_ptr upsample;
int ci;
jpeg_component_info * compptr;
- boolean need_buffer, do_fancy;
+ boolean need_buffer;
int h_in_group, v_in_group, h_out_group, v_out_group;
upsample = (my_upsample_ptr)
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.
*/
/* 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_in_group = (compptr->h_samp_factor * compptr->DCT_h_scaled_size) /
+ cinfo->min_DCT_h_scaled_size;
+ v_in_group = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) /
+ cinfo->min_DCT_v_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 = 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;
+ /* Special case for 2h1v upsampling */
+ 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;
+ /* Special case for 2h2v upsampling */
+ 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 */
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