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451 lines
15 KiB
451 lines
15 KiB
/* |
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* jdmerge.c |
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* |
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* Copyright (C) 1994-1996, Thomas G. Lane. |
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* Modified 2013-2017 by Guido Vollbeding. |
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* This file is part of the Independent JPEG Group's software. |
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* For conditions of distribution and use, see the accompanying README file. |
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* |
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* This file contains code for merged upsampling/color conversion. |
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* |
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* This file combines functions from jdsample.c and jdcolor.c; |
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* read those files first to understand what's going on. |
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* |
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* When the chroma components are to be upsampled by simple replication |
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* (ie, box filtering), we can save some work in color conversion by |
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* calculating all the output pixels corresponding to a pair of chroma |
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* samples at one time. In the conversion equations |
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* R = Y + K1 * Cr |
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* G = Y + K2 * Cb + K3 * Cr |
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* B = Y + K4 * Cb |
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* only the Y term varies among the group of pixels corresponding to a pair |
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* of chroma samples, so the rest of the terms can be calculated just once. |
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* At typical sampling ratios, this eliminates half or three-quarters of the |
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* multiplications needed for color conversion. |
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* |
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* This file currently provides implementations for the following cases: |
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* YCC => RGB color conversion only (YCbCr or BG_YCC). |
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* Sampling ratios of 2h1v or 2h2v. |
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* No scaling needed at upsample time. |
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* Corner-aligned (non-CCIR601) sampling alignment. |
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* Other special cases could be added, but in most applications these are |
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* the only common cases. (For uncommon cases we fall back on the more |
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* general code in jdsample.c and jdcolor.c.) |
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*/ |
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#define JPEG_INTERNALS |
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#include "jinclude.h" |
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#include "jpeglib.h" |
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#ifdef UPSAMPLE_MERGING_SUPPORTED |
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#if RANGE_BITS < 2 |
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/* Deliberate syntax err */ |
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Sorry, this code requires 2 or more range extension bits. |
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#endif |
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/* Private subobject */ |
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typedef struct { |
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struct jpeg_upsampler pub; /* public fields */ |
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/* Pointer to routine to do actual upsampling/conversion of one row group */ |
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JMETHOD(void, upmethod, (j_decompress_ptr cinfo, |
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JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, |
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JSAMPARRAY output_buf)); |
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/* Private state for YCC->RGB conversion */ |
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int * Cr_r_tab; /* => table for Cr to R conversion */ |
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int * Cb_b_tab; /* => table for Cb to B conversion */ |
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INT32 * Cr_g_tab; /* => table for Cr to G conversion */ |
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INT32 * Cb_g_tab; /* => table for Cb to G conversion */ |
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/* For 2:1 vertical sampling, we produce two output rows at a time. |
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* We need a "spare" row buffer to hold the second output row if the |
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* application provides just a one-row buffer; we also use the spare |
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* to discard the dummy last row if the image height is odd. |
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*/ |
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JSAMPROW spare_row; |
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boolean spare_full; /* T if spare buffer is occupied */ |
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JDIMENSION out_row_width; /* samples per output row */ |
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JDIMENSION rows_to_go; /* counts rows remaining in image */ |
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} my_upsampler; |
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typedef my_upsampler * my_upsample_ptr; |
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#define SCALEBITS 16 /* speediest right-shift on some machines */ |
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#define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) |
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#define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) |
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/* |
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* Initialize tables for YCbCr->RGB and BG_YCC->RGB colorspace conversion. |
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* This is taken directly from jdcolor.c; see that file for more info. |
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*/ |
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LOCAL(void) |
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build_ycc_rgb_table (j_decompress_ptr cinfo) |
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/* Normal case, sYCC */ |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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int i; |
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INT32 x; |
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SHIFT_TEMPS |
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upsample->Cr_r_tab = (int *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(int)); |
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upsample->Cb_b_tab = (int *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(int)); |
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upsample->Cr_g_tab = (INT32 *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(INT32)); |
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upsample->Cb_g_tab = (INT32 *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(INT32)); |
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for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { |
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/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ |
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/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ |
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/* Cr=>R value is nearest int to 1.402 * x */ |
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upsample->Cr_r_tab[i] = (int) |
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RIGHT_SHIFT(FIX(1.402) * x + ONE_HALF, SCALEBITS); |
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/* Cb=>B value is nearest int to 1.772 * x */ |
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upsample->Cb_b_tab[i] = (int) |
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RIGHT_SHIFT(FIX(1.772) * x + ONE_HALF, SCALEBITS); |
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/* Cr=>G value is scaled-up -0.714136286 * x */ |
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upsample->Cr_g_tab[i] = (- FIX(0.714136286)) * x; |
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/* Cb=>G value is scaled-up -0.344136286 * x */ |
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/* We also add in ONE_HALF so that need not do it in inner loop */ |
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upsample->Cb_g_tab[i] = (- FIX(0.344136286)) * x + ONE_HALF; |
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} |
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} |
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LOCAL(void) |
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build_bg_ycc_rgb_table (j_decompress_ptr cinfo) |
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/* Wide gamut case, bg-sYCC */ |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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int i; |
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INT32 x; |
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SHIFT_TEMPS |
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upsample->Cr_r_tab = (int *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(int)); |
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upsample->Cb_b_tab = (int *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(int)); |
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upsample->Cr_g_tab = (INT32 *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(INT32)); |
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upsample->Cb_g_tab = (INT32 *) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(MAXJSAMPLE+1) * SIZEOF(INT32)); |
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for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { |
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/* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ |
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/* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ |
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/* Cr=>R value is nearest int to 2.804 * x */ |
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upsample->Cr_r_tab[i] = (int) |
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RIGHT_SHIFT(FIX(2.804) * x + ONE_HALF, SCALEBITS); |
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/* Cb=>B value is nearest int to 3.544 * x */ |
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upsample->Cb_b_tab[i] = (int) |
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RIGHT_SHIFT(FIX(3.544) * x + ONE_HALF, SCALEBITS); |
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/* Cr=>G value is scaled-up -1.428272572 * x */ |
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upsample->Cr_g_tab[i] = (- FIX(1.428272572)) * x; |
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/* Cb=>G value is scaled-up -0.688272572 * x */ |
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/* We also add in ONE_HALF so that need not do it in inner loop */ |
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upsample->Cb_g_tab[i] = (- FIX(0.688272572)) * x + ONE_HALF; |
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} |
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} |
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/* |
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* Initialize for an upsampling pass. |
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*/ |
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METHODDEF(void) |
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start_pass_merged_upsample (j_decompress_ptr cinfo) |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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/* Mark the spare buffer empty */ |
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upsample->spare_full = FALSE; |
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/* Initialize total-height counter for detecting bottom of image */ |
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upsample->rows_to_go = cinfo->output_height; |
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} |
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/* |
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* Control routine to do upsampling (and color conversion). |
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* |
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* The control routine just handles the row buffering considerations. |
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*/ |
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METHODDEF(void) |
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merged_2v_upsample (j_decompress_ptr cinfo, |
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
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JDIMENSION in_row_groups_avail, |
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
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JDIMENSION out_rows_avail) |
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/* 2:1 vertical sampling case: may need a spare row. */ |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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JSAMPROW work_ptrs[2]; |
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JDIMENSION num_rows; /* number of rows returned to caller */ |
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if (upsample->spare_full) { |
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/* If we have a spare row saved from a previous cycle, just return it. */ |
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jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0, |
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1, upsample->out_row_width); |
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num_rows = 1; |
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upsample->spare_full = FALSE; |
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} else { |
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/* Figure number of rows to return to caller. */ |
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num_rows = 2; |
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/* Not more than the distance to the end of the image. */ |
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if (num_rows > upsample->rows_to_go) |
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num_rows = upsample->rows_to_go; |
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/* And not more than what the client can accept: */ |
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out_rows_avail -= *out_row_ctr; |
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if (num_rows > out_rows_avail) |
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num_rows = out_rows_avail; |
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/* Create output pointer array for upsampler. */ |
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work_ptrs[0] = output_buf[*out_row_ctr]; |
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if (num_rows > 1) { |
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work_ptrs[1] = output_buf[*out_row_ctr + 1]; |
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} else { |
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work_ptrs[1] = upsample->spare_row; |
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upsample->spare_full = TRUE; |
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} |
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/* Now do the upsampling. */ |
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(*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs); |
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} |
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/* Adjust counts */ |
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*out_row_ctr += num_rows; |
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upsample->rows_to_go -= num_rows; |
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/* When the buffer is emptied, declare this input row group consumed */ |
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if (! upsample->spare_full) |
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(*in_row_group_ctr)++; |
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} |
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METHODDEF(void) |
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merged_1v_upsample (j_decompress_ptr cinfo, |
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JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
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JDIMENSION in_row_groups_avail, |
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JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
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JDIMENSION out_rows_avail) |
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/* 1:1 vertical sampling case: much easier, never need a spare row. */ |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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/* Just do the upsampling. */ |
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(*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, |
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output_buf + *out_row_ctr); |
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/* Adjust counts */ |
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(*out_row_ctr)++; |
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(*in_row_group_ctr)++; |
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} |
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/* |
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* These are the routines invoked by the control routines to do |
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* the actual upsampling/conversion. One row group is processed per call. |
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* |
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* Note: since we may be writing directly into application-supplied buffers, |
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* we have to be honest about the output width; we can't assume the buffer |
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* has been rounded up to an even width. |
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*/ |
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/* |
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* Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical. |
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*/ |
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METHODDEF(void) |
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h2v1_merged_upsample (j_decompress_ptr cinfo, |
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JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, |
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JSAMPARRAY output_buf) |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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register int y, cred, cgreen, cblue; |
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int cb, cr; |
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register JSAMPROW outptr; |
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JSAMPROW inptr0, inptr1, inptr2; |
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JDIMENSION col; |
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/* copy these pointers into registers if possible */ |
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register JSAMPLE * range_limit = cinfo->sample_range_limit; |
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int * Crrtab = upsample->Cr_r_tab; |
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int * Cbbtab = upsample->Cb_b_tab; |
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INT32 * Crgtab = upsample->Cr_g_tab; |
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INT32 * Cbgtab = upsample->Cb_g_tab; |
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SHIFT_TEMPS |
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inptr0 = input_buf[0][in_row_group_ctr]; |
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inptr1 = input_buf[1][in_row_group_ctr]; |
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inptr2 = input_buf[2][in_row_group_ctr]; |
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outptr = output_buf[0]; |
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/* Loop for each pair of output pixels */ |
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for (col = cinfo->output_width >> 1; col > 0; col--) { |
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/* Do the chroma part of the calculation */ |
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cb = GETJSAMPLE(*inptr1++); |
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cr = GETJSAMPLE(*inptr2++); |
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cred = Crrtab[cr]; |
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cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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cblue = Cbbtab[cb]; |
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/* Fetch 2 Y values and emit 2 pixels */ |
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y = GETJSAMPLE(*inptr0++); |
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outptr[RGB_RED] = range_limit[y + cred]; |
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outptr[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr[RGB_BLUE] = range_limit[y + cblue]; |
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outptr += RGB_PIXELSIZE; |
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y = GETJSAMPLE(*inptr0++); |
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outptr[RGB_RED] = range_limit[y + cred]; |
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outptr[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr[RGB_BLUE] = range_limit[y + cblue]; |
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outptr += RGB_PIXELSIZE; |
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} |
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/* If image width is odd, do the last output column separately */ |
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if (cinfo->output_width & 1) { |
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cb = GETJSAMPLE(*inptr1); |
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cr = GETJSAMPLE(*inptr2); |
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cred = Crrtab[cr]; |
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cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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cblue = Cbbtab[cb]; |
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y = GETJSAMPLE(*inptr0); |
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outptr[RGB_RED] = range_limit[y + cred]; |
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outptr[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr[RGB_BLUE] = range_limit[y + cblue]; |
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} |
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} |
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/* |
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* Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical. |
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*/ |
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METHODDEF(void) |
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h2v2_merged_upsample (j_decompress_ptr cinfo, |
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JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, |
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JSAMPARRAY output_buf) |
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{ |
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my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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register int y, cred, cgreen, cblue; |
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int cb, cr; |
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register JSAMPROW outptr0, outptr1; |
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JSAMPROW inptr00, inptr01, inptr1, inptr2; |
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JDIMENSION col; |
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/* copy these pointers into registers if possible */ |
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register JSAMPLE * range_limit = cinfo->sample_range_limit; |
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int * Crrtab = upsample->Cr_r_tab; |
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int * Cbbtab = upsample->Cb_b_tab; |
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INT32 * Crgtab = upsample->Cr_g_tab; |
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INT32 * Cbgtab = upsample->Cb_g_tab; |
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SHIFT_TEMPS |
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inptr00 = input_buf[0][in_row_group_ctr*2]; |
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inptr01 = input_buf[0][in_row_group_ctr*2 + 1]; |
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inptr1 = input_buf[1][in_row_group_ctr]; |
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inptr2 = input_buf[2][in_row_group_ctr]; |
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outptr0 = output_buf[0]; |
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outptr1 = output_buf[1]; |
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/* Loop for each group of output pixels */ |
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for (col = cinfo->output_width >> 1; col > 0; col--) { |
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/* Do the chroma part of the calculation */ |
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cb = GETJSAMPLE(*inptr1++); |
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cr = GETJSAMPLE(*inptr2++); |
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cred = Crrtab[cr]; |
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cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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cblue = Cbbtab[cb]; |
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/* Fetch 4 Y values and emit 4 pixels */ |
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y = GETJSAMPLE(*inptr00++); |
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outptr0[RGB_RED] = range_limit[y + cred]; |
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outptr0[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr0[RGB_BLUE] = range_limit[y + cblue]; |
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outptr0 += RGB_PIXELSIZE; |
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y = GETJSAMPLE(*inptr00++); |
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outptr0[RGB_RED] = range_limit[y + cred]; |
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outptr0[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr0[RGB_BLUE] = range_limit[y + cblue]; |
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outptr0 += RGB_PIXELSIZE; |
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y = GETJSAMPLE(*inptr01++); |
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outptr1[RGB_RED] = range_limit[y + cred]; |
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outptr1[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr1[RGB_BLUE] = range_limit[y + cblue]; |
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outptr1 += RGB_PIXELSIZE; |
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y = GETJSAMPLE(*inptr01++); |
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outptr1[RGB_RED] = range_limit[y + cred]; |
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outptr1[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr1[RGB_BLUE] = range_limit[y + cblue]; |
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outptr1 += RGB_PIXELSIZE; |
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} |
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/* If image width is odd, do the last output column separately */ |
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if (cinfo->output_width & 1) { |
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cb = GETJSAMPLE(*inptr1); |
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cr = GETJSAMPLE(*inptr2); |
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cred = Crrtab[cr]; |
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cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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cblue = Cbbtab[cb]; |
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y = GETJSAMPLE(*inptr00); |
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outptr0[RGB_RED] = range_limit[y + cred]; |
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outptr0[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr0[RGB_BLUE] = range_limit[y + cblue]; |
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y = GETJSAMPLE(*inptr01); |
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outptr1[RGB_RED] = range_limit[y + cred]; |
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outptr1[RGB_GREEN] = range_limit[y + cgreen]; |
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outptr1[RGB_BLUE] = range_limit[y + cblue]; |
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} |
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} |
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/* |
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* Module initialization routine for merged upsampling/color conversion. |
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* |
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* NB: this is called under the conditions determined by use_merged_upsample() |
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* in jdmaster.c. That routine MUST correspond to the actual capabilities |
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* of this module; no safety checks are made here. |
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*/ |
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GLOBAL(void) |
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jinit_merged_upsampler (j_decompress_ptr cinfo) |
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{ |
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my_upsample_ptr upsample; |
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upsample = (my_upsample_ptr) |
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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SIZEOF(my_upsampler)); |
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cinfo->upsample = &upsample->pub; |
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upsample->pub.start_pass = start_pass_merged_upsample; |
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upsample->pub.need_context_rows = FALSE; |
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upsample->out_row_width = cinfo->output_width * cinfo->out_color_components; |
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if (cinfo->max_v_samp_factor == 2) { |
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upsample->pub.upsample = merged_2v_upsample; |
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upsample->upmethod = h2v2_merged_upsample; |
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/* Allocate a spare row buffer */ |
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upsample->spare_row = (JSAMPROW) |
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(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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(size_t) (upsample->out_row_width * SIZEOF(JSAMPLE))); |
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} else { |
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upsample->pub.upsample = merged_1v_upsample; |
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upsample->upmethod = h2v1_merged_upsample; |
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/* No spare row needed */ |
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upsample->spare_row = NULL; |
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} |
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if (cinfo->jpeg_color_space == JCS_BG_YCC) |
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build_bg_ycc_rgb_table(cinfo); |
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else |
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build_ycc_rgb_table(cinfo); |
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} |
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#endif /* UPSAMPLE_MERGING_SUPPORTED */
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