| /* |
| * 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 */ |