+++ /dev/null
-/*
- * jdsample.c
- *
- * Copyright (C) 1991-1994, 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 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)
- * 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).
- *
- * 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.
- */
-
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "radiant_jpeglib.h"
-
-
-/* Pointer to routine to upsample a single component */
-typedef JMETHOD(void, upsample1_ptr,
- (j_decompress_ptr cinfo, jpeg_component_info * compptr,
- JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
-
-/* Private subobject */
-
-typedef struct {
- struct jpeg_upsampler pub; /* public fields */
-
- /* Color conversion buffer. When using separate upsampling and color
- * conversion steps, this buffer holds one upsampled row group until it
- * has been color converted and output.
- * Note: we do not allocate any storage for component(s) which are full-size,
- * ie do not need rescaling. The corresponding entry of color_buf[] is
- * simply set to point to the input data array, thereby avoiding copying.
- */
- JSAMPARRAY color_buf[MAX_COMPONENTS];
-
- /* Per-component upsampling method pointers */
- upsample1_ptr methods[MAX_COMPONENTS];
-
- int next_row_out; /* counts rows emitted from color_buf */
- JDIMENSION rows_to_go; /* counts rows remaining in image */
-
- /* Height of an input row group for each component. */
- int rowgroup_height[MAX_COMPONENTS];
-
- /* These arrays save pixel expansion factors so that int_expand need not
- * recompute them each time. They are unused for other upsampling methods.
- */
- UINT8 h_expand[MAX_COMPONENTS];
- UINT8 v_expand[MAX_COMPONENTS];
-} my_upsampler;
-
-typedef my_upsampler * my_upsample_ptr;
-
-
-/*
- * Initialize for an upsampling pass.
- */
-
-METHODDEF void
-start_pass_upsample (j_decompress_ptr cinfo)
-{
- 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;
-}
-
-
-/*
- * Control routine to do upsampling (and color conversion).
- *
- * In this version we upsample each component independently.
- * We upsample one row group into the conversion buffer, then apply
- * color conversion a row at a time.
- */
-
-METHODDEF 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)
-{
- 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)++;
-}
-
-
-/*
- * These are the routines invoked by sep_upsample to upsample pixel values
- * of a single component. One row group is processed per call.
- */
-
-
-/*
- * For full-size components, we just make color_buf[ci] point at the
- * input buffer, and thus avoid copying any data. Note that this is
- * safe only because sep_upsample doesn't declare the input row group
- * "consumed" until we are done color converting and emitting it.
- */
-
-METHODDEF void
-fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
- JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
-{
- *output_data_ptr = input_data;
-}
-
-
-/*
- * This is a no-op version used for "uninteresting" components.
- * These components will not be referenced by color conversion.
- */
-
-METHODDEF void
-noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
- JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
-{
- *output_data_ptr = NULL; /* safety check */
-}
-
-
-/*
- * This version handles any integral sampling ratios.
- * This is not used for typical JPEG files, so it need not be fast.
- * Nor, for that matter, is it particularly accurate: the algorithm is
- * simple replication of the input pixel onto the corresponding output
- * pixels. The hi-falutin sampling literature refers to this as a
- * "box filter". A box filter tends to introduce visible artifacts,
- * so if you are actually going to use 3:1 or 4:1 sampling ratios
- * you would be well advised to improve this code.
- */
-
-METHODDEF void
-int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
- JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
-{
- 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;
- }
-}
-
-
-/*
- * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
- * It's still a box filter.
- */
-
-METHODDEF void
-h2v1_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;
-
- 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);
- }
- }
-}
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