--- /dev/null
+/*
+ * jdmerge.c
+ *
+ * Copyright (C) 1994-1996, 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 code for merged upsampling/color conversion.
+ *
+ * This file combines functions from jdsample.c and jdcolor.c;
+ * read those files first to understand what's going on.
+ *
+ * When the chroma components are to be upsampled by simple replication
+ * (ie, box filtering), we can save some work in color conversion by
+ * calculating all the output pixels corresponding to a pair of chroma
+ * samples at one time. In the conversion equations
+ * R = Y + K1 * Cr
+ * G = Y + K2 * Cb + K3 * Cr
+ * B = Y + K4 * Cb
+ * only the Y term varies among the group of pixels corresponding to a pair
+ * of chroma samples, so the rest of the terms can be calculated just once.
+ * At typical sampling ratios, this eliminates half or three-quarters of the
+ * multiplications needed for color conversion.
+ *
+ * This file currently provides implementations for the following cases:
+ * YCbCr => RGB color conversion only.
+ * Sampling ratios of 2h1v or 2h2v.
+ * No scaling needed at upsample time.
+ * Corner-aligned (non-CCIR601) sampling alignment.
+ * Other special cases could be added, but in most applications these are
+ * the only common cases. (For uncommon cases we fall back on the more
+ * general code in jdsample.c and jdcolor.c.)
+ */
+
+#define JPEG_INTERNALS
+#include "jinclude.h"
+#include "jpeglib.h"
+
+#ifdef UPSAMPLE_MERGING_SUPPORTED
+
+
+/* Private subobject */
+
+typedef struct {
+ struct jpeg_upsampler pub; /* public fields */
+
+ /* Pointer to routine to do actual upsampling/conversion of one row group */
+ JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
+ JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
+ JSAMPARRAY output_buf));
+
+ /* Private state for YCC->RGB conversion */
+ int * Cr_r_tab; /* => table for Cr to R conversion */
+ int * Cb_b_tab; /* => table for Cb to B conversion */
+ INT32 * Cr_g_tab; /* => table for Cr to G conversion */
+ INT32 * Cb_g_tab; /* => table for Cb to G conversion */
+
+ /* For 2:1 vertical sampling, we produce two output rows at a time.
+ * We need a "spare" row buffer to hold the second output row if the
+ * application provides just a one-row buffer; we also use the spare
+ * to discard the dummy last row if the image height is odd.
+ */
+ JSAMPROW spare_row;
+ boolean spare_full; /* T if spare buffer is occupied */
+
+ JDIMENSION out_row_width; /* samples per output row */
+ JDIMENSION rows_to_go; /* counts rows remaining in image */
+} my_upsampler;
+
+typedef my_upsampler * my_upsample_ptr;
+
+#define SCALEBITS 16 /* speediest right-shift on some machines */
+#define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
+#define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
+
+
+/*
+ * Initialize tables for YCC->RGB colorspace conversion.
+ * This is taken directly from jdcolor.c; see that file for more info.
+ */
+
+LOCAL(void)
+build_ycc_rgb_table (j_decompress_ptr cinfo)
+{
+ my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
+ int i;
+ INT32 x;
+ SHIFT_TEMPS
+
+ upsample->Cr_r_tab = (int *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (MAXJSAMPLE+1) * SIZEOF(int));
+ upsample->Cb_b_tab = (int *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (MAXJSAMPLE+1) * SIZEOF(int));
+ upsample->Cr_g_tab = (INT32 *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (MAXJSAMPLE+1) * SIZEOF(INT32));
+ upsample->Cb_g_tab = (INT32 *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (MAXJSAMPLE+1) * SIZEOF(INT32));
+
+ for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
+ /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
+ /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
+ /* Cr=>R value is nearest int to 1.40200 * x */
+ upsample->Cr_r_tab[i] = (int)
+ RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
+ /* Cb=>B value is nearest int to 1.77200 * x */
+ upsample->Cb_b_tab[i] = (int)
+ RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
+ /* Cr=>G value is scaled-up -0.71414 * x */
+ upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x;
+ /* Cb=>G value is scaled-up -0.34414 * x */
+ /* We also add in ONE_HALF so that need not do it in inner loop */
+ upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
+ }
+}
+
+
+/*
+ * Initialize for an upsampling pass.
+ */
+
+METHODDEF(void)
+start_pass_merged_upsample (j_decompress_ptr cinfo)
+{
+ my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
+
+ /* Mark the spare buffer empty */
+ upsample->spare_full = FALSE;
+ /* Initialize total-height counter for detecting bottom of image */
+ upsample->rows_to_go = cinfo->output_height;
+}
+
+
+/*
+ * Control routine to do upsampling (and color conversion).
+ *
+ * The control routine just handles the row buffering considerations.
+ */
+
+METHODDEF(void)
+merged_2v_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)
+/* 2:1 vertical sampling case: may need a spare row. */
+{
+ my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
+ JSAMPROW work_ptrs[2];
+ JDIMENSION num_rows; /* number of rows returned to caller */
+
+ if (upsample->spare_full) {
+ /* If we have a spare row saved from a previous cycle, just return it. */
+ jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
+ 1, upsample->out_row_width);
+ num_rows = 1;
+ upsample->spare_full = FALSE;
+ } else {
+ /* Figure number of rows to return to caller. */
+ num_rows = 2;
+ /* Not more than the distance to the end of the image. */
+ 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;
+ /* Create output pointer array for upsampler. */
+ work_ptrs[0] = output_buf[*out_row_ctr];
+ if (num_rows > 1) {
+ work_ptrs[1] = output_buf[*out_row_ctr + 1];
+ } else {
+ work_ptrs[1] = upsample->spare_row;
+ upsample->spare_full = TRUE;
+ }
+ /* Now do the upsampling. */
+ (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);
+ }
+
+ /* Adjust counts */
+ *out_row_ctr += num_rows;
+ upsample->rows_to_go -= num_rows;
+ /* When the buffer is emptied, declare this input row group consumed */
+ if (! upsample->spare_full)
+ (*in_row_group_ctr)++;
+}
+
+
+METHODDEF(void)
+merged_1v_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)
+/* 1:1 vertical sampling case: much easier, never need a spare row. */
+{
+ my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
+
+ /* Just do the upsampling. */
+ (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,
+ output_buf + *out_row_ctr);
+ /* Adjust counts */
+ (*out_row_ctr)++;
+ (*in_row_group_ctr)++;
+}
+
+
+/*
+ * These are the routines invoked by the control routines to do
+ * the actual upsampling/conversion. One row group is processed per call.
+ *
+ * Note: since we may be writing directly into application-supplied buffers,
+ * we have to be honest about the output width; we can't assume the buffer
+ * has been rounded up to an even width.
+ */
+
+
+/*
+ * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
+ */
+
+METHODDEF(void)
+h2v1_merged_upsample (j_decompress_ptr cinfo,
+ JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
+ JSAMPARRAY output_buf)
+{
+ my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
+ register int y, cred, cgreen, cblue;
+ int cb, cr;
+ register JSAMPROW outptr;
+ JSAMPROW inptr0, inptr1, inptr2;
+ JDIMENSION col;
+ /* copy these pointers into registers if possible */
+ register JSAMPLE * range_limit = cinfo->sample_range_limit;
+ int * Crrtab = upsample->Cr_r_tab;
+ int * Cbbtab = upsample->Cb_b_tab;
+ INT32 * Crgtab = upsample->Cr_g_tab;
+ INT32 * Cbgtab = upsample->Cb_g_tab;
+ SHIFT_TEMPS
+
+ inptr0 = input_buf[0][in_row_group_ctr];
+ inptr1 = input_buf[1][in_row_group_ctr];
+ inptr2 = input_buf[2][in_row_group_ctr];
+ outptr = output_buf[0];
+ /* Loop for each pair of output pixels */
+ for (col = cinfo->output_width >> 1; col > 0; col--) {
+ /* Do the chroma part of the calculation */
+ cb = GETJSAMPLE(*inptr1++);
+ cr = GETJSAMPLE(*inptr2++);
+ cred = Crrtab[cr];
+ cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
+ cblue = Cbbtab[cb];
+ /* Fetch 2 Y values and emit 2 pixels */
+ y = GETJSAMPLE(*inptr0++);
+ outptr[RGB_RED] = range_limit[y + cred];
+ outptr[RGB_GREEN] = range_limit[y + cgreen];
+ outptr[RGB_BLUE] = range_limit[y + cblue];
+ outptr += RGB_PIXELSIZE;
+ y = GETJSAMPLE(*inptr0++);
+ outptr[RGB_RED] = range_limit[y + cred];
+ outptr[RGB_GREEN] = range_limit[y + cgreen];
+ outptr[RGB_BLUE] = range_limit[y + cblue];
+ outptr += RGB_PIXELSIZE;
+ }
+ /* If image width is odd, do the last output column separately */
+ if (cinfo->output_width & 1) {
+ cb = GETJSAMPLE(*inptr1);
+ cr = GETJSAMPLE(*inptr2);
+ cred = Crrtab[cr];
+ cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
+ cblue = Cbbtab[cb];
+ y = GETJSAMPLE(*inptr0);
+ outptr[RGB_RED] = range_limit[y + cred];
+ outptr[RGB_GREEN] = range_limit[y + cgreen];
+ outptr[RGB_BLUE] = range_limit[y + cblue];
+ }
+}
+
+
+/*
+ * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
+ */
+
+METHODDEF(void)
+h2v2_merged_upsample (j_decompress_ptr cinfo,
+ JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
+ JSAMPARRAY output_buf)
+{
+ my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
+ register int y, cred, cgreen, cblue;
+ int cb, cr;
+ register JSAMPROW outptr0, outptr1;
+ JSAMPROW inptr00, inptr01, inptr1, inptr2;
+ JDIMENSION col;
+ /* copy these pointers into registers if possible */
+ register JSAMPLE * range_limit = cinfo->sample_range_limit;
+ int * Crrtab = upsample->Cr_r_tab;
+ int * Cbbtab = upsample->Cb_b_tab;
+ INT32 * Crgtab = upsample->Cr_g_tab;
+ INT32 * Cbgtab = upsample->Cb_g_tab;
+ SHIFT_TEMPS
+
+ inptr00 = input_buf[0][in_row_group_ctr*2];
+ inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
+ inptr1 = input_buf[1][in_row_group_ctr];
+ inptr2 = input_buf[2][in_row_group_ctr];
+ outptr0 = output_buf[0];
+ outptr1 = output_buf[1];
+ /* Loop for each group of output pixels */
+ for (col = cinfo->output_width >> 1; col > 0; col--) {
+ /* Do the chroma part of the calculation */
+ cb = GETJSAMPLE(*inptr1++);
+ cr = GETJSAMPLE(*inptr2++);
+ cred = Crrtab[cr];
+ cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
+ cblue = Cbbtab[cb];
+ /* Fetch 4 Y values and emit 4 pixels */
+ y = GETJSAMPLE(*inptr00++);
+ outptr0[RGB_RED] = range_limit[y + cred];
+ outptr0[RGB_GREEN] = range_limit[y + cgreen];
+ outptr0[RGB_BLUE] = range_limit[y + cblue];
+ outptr0 += RGB_PIXELSIZE;
+ y = GETJSAMPLE(*inptr00++);
+ outptr0[RGB_RED] = range_limit[y + cred];
+ outptr0[RGB_GREEN] = range_limit[y + cgreen];
+ outptr0[RGB_BLUE] = range_limit[y + cblue];
+ outptr0 += RGB_PIXELSIZE;
+ y = GETJSAMPLE(*inptr01++);
+ outptr1[RGB_RED] = range_limit[y + cred];
+ outptr1[RGB_GREEN] = range_limit[y + cgreen];
+ outptr1[RGB_BLUE] = range_limit[y + cblue];
+ outptr1 += RGB_PIXELSIZE;
+ y = GETJSAMPLE(*inptr01++);
+ outptr1[RGB_RED] = range_limit[y + cred];
+ outptr1[RGB_GREEN] = range_limit[y + cgreen];
+ outptr1[RGB_BLUE] = range_limit[y + cblue];
+ outptr1 += RGB_PIXELSIZE;
+ }
+ /* If image width is odd, do the last output column separately */
+ if (cinfo->output_width & 1) {
+ cb = GETJSAMPLE(*inptr1);
+ cr = GETJSAMPLE(*inptr2);
+ cred = Crrtab[cr];
+ cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
+ cblue = Cbbtab[cb];
+ y = GETJSAMPLE(*inptr00);
+ outptr0[RGB_RED] = range_limit[y + cred];
+ outptr0[RGB_GREEN] = range_limit[y + cgreen];
+ outptr0[RGB_BLUE] = range_limit[y + cblue];
+ y = GETJSAMPLE(*inptr01);
+ outptr1[RGB_RED] = range_limit[y + cred];
+ outptr1[RGB_GREEN] = range_limit[y + cgreen];
+ outptr1[RGB_BLUE] = range_limit[y + cblue];
+ }
+}
+
+
+/*
+ * Module initialization routine for merged upsampling/color conversion.
+ *
+ * NB: this is called under the conditions determined by use_merged_upsample()
+ * in jdmaster.c. That routine MUST correspond to the actual capabilities
+ * of this module; no safety checks are made here.
+ */
+
+GLOBAL(void)
+jinit_merged_upsampler (j_decompress_ptr cinfo)
+{
+ my_upsample_ptr upsample;
+
+ 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_merged_upsample;
+ upsample->pub.need_context_rows = FALSE;
+
+ upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
+
+ if (cinfo->max_v_samp_factor == 2) {
+ upsample->pub.upsample = merged_2v_upsample;
+ upsample->upmethod = h2v2_merged_upsample;
+ /* Allocate a spare row buffer */
+ upsample->spare_row = (JSAMPROW)
+ (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
+ } else {
+ upsample->pub.upsample = merged_1v_upsample;
+ upsample->upmethod = h2v1_merged_upsample;
+ /* No spare row needed */
+ upsample->spare_row = NULL;
+ }
+
+ build_ycc_rgb_table(cinfo);
+}
+
+#endif /* UPSAMPLE_MERGING_SUPPORTED */
projects / opencv / blobdiff