ref: b56909157f0cd2491cd2918f7923676f22b5707c
dir: /sys/src/cmd/gs/jpeg/jdmerge.c/
/* * 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 */