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Diffstat (limited to 'jpeg/jdmerge.c')
| -rw-r--r-- | jpeg/jdmerge.c | 400 |
1 files changed, 400 insertions, 0 deletions
diff --git a/jpeg/jdmerge.c b/jpeg/jdmerge.c new file mode 100644 index 0000000..3744446 --- /dev/null +++ b/jpeg/jdmerge.c @@ -0,0 +1,400 @@ +/* + * 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 */ |