nuclear@26: /*
nuclear@26:  * jdmerge.c
nuclear@26:  *
nuclear@26:  * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@26:  * This file is part of the Independent JPEG Group's software.
nuclear@26:  * For conditions of distribution and use, see the accompanying README file.
nuclear@26:  *
nuclear@26:  * This file contains code for merged upsampling/color conversion.
nuclear@26:  *
nuclear@26:  * This file combines functions from jdsample.c and jdcolor.c;
nuclear@26:  * read those files first to understand what's going on.
nuclear@26:  *
nuclear@26:  * When the chroma components are to be upsampled by simple replication
nuclear@26:  * (ie, box filtering), we can save some work in color conversion by
nuclear@26:  * calculating all the output pixels corresponding to a pair of chroma
nuclear@26:  * samples at one time.  In the conversion equations
nuclear@26:  *	R = Y           + K1 * Cr
nuclear@26:  *	G = Y + K2 * Cb + K3 * Cr
nuclear@26:  *	B = Y + K4 * Cb
nuclear@26:  * only the Y term varies among the group of pixels corresponding to a pair
nuclear@26:  * of chroma samples, so the rest of the terms can be calculated just once.
nuclear@26:  * At typical sampling ratios, this eliminates half or three-quarters of the
nuclear@26:  * multiplications needed for color conversion.
nuclear@26:  *
nuclear@26:  * This file currently provides implementations for the following cases:
nuclear@26:  *	YCbCr => RGB color conversion only.
nuclear@26:  *	Sampling ratios of 2h1v or 2h2v.
nuclear@26:  *	No scaling needed at upsample time.
nuclear@26:  *	Corner-aligned (non-CCIR601) sampling alignment.
nuclear@26:  * Other special cases could be added, but in most applications these are
nuclear@26:  * the only common cases.  (For uncommon cases we fall back on the more
nuclear@26:  * general code in jdsample.c and jdcolor.c.)
nuclear@26:  */
nuclear@26: 
nuclear@26: #define JPEG_INTERNALS
nuclear@26: #include "jinclude.h"
nuclear@26: #include "jpeglib.h"
nuclear@26: 
nuclear@26: #ifdef UPSAMPLE_MERGING_SUPPORTED
nuclear@26: 
nuclear@26: 
nuclear@26: /* Private subobject */
nuclear@26: 
nuclear@26: typedef struct {
nuclear@26:   struct jpeg_upsampler pub;	/* public fields */
nuclear@26: 
nuclear@26:   /* Pointer to routine to do actual upsampling/conversion of one row group */
nuclear@26:   JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
nuclear@26: 			   JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
nuclear@26: 			   JSAMPARRAY output_buf));
nuclear@26: 
nuclear@26:   /* Private state for YCC->RGB conversion */
nuclear@26:   int * Cr_r_tab;		/* => table for Cr to R conversion */
nuclear@26:   int * Cb_b_tab;		/* => table for Cb to B conversion */
nuclear@26:   INT32 * Cr_g_tab;		/* => table for Cr to G conversion */
nuclear@26:   INT32 * Cb_g_tab;		/* => table for Cb to G conversion */
nuclear@26: 
nuclear@26:   /* For 2:1 vertical sampling, we produce two output rows at a time.
nuclear@26:    * We need a "spare" row buffer to hold the second output row if the
nuclear@26:    * application provides just a one-row buffer; we also use the spare
nuclear@26:    * to discard the dummy last row if the image height is odd.
nuclear@26:    */
nuclear@26:   JSAMPROW spare_row;
nuclear@26:   boolean spare_full;		/* T if spare buffer is occupied */
nuclear@26: 
nuclear@26:   JDIMENSION out_row_width;	/* samples per output row */
nuclear@26:   JDIMENSION rows_to_go;	/* counts rows remaining in image */
nuclear@26: } my_upsampler;
nuclear@26: 
nuclear@26: typedef my_upsampler * my_upsample_ptr;
nuclear@26: 
nuclear@26: #define SCALEBITS	16	/* speediest right-shift on some machines */
nuclear@26: #define ONE_HALF	((INT32) 1 << (SCALEBITS-1))
nuclear@26: #define FIX(x)		((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * Initialize tables for YCC->RGB colorspace conversion.
nuclear@26:  * This is taken directly from jdcolor.c; see that file for more info.
nuclear@26:  */
nuclear@26: 
nuclear@26: LOCAL(void)
nuclear@26: build_ycc_rgb_table (j_decompress_ptr cinfo)
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26:   int i;
nuclear@26:   INT32 x;
nuclear@26:   SHIFT_TEMPS
nuclear@26: 
nuclear@26:   upsample->Cr_r_tab = (int *)
nuclear@26:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26: 				(MAXJSAMPLE+1) * SIZEOF(int));
nuclear@26:   upsample->Cb_b_tab = (int *)
nuclear@26:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26: 				(MAXJSAMPLE+1) * SIZEOF(int));
nuclear@26:   upsample->Cr_g_tab = (INT32 *)
nuclear@26:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26: 				(MAXJSAMPLE+1) * SIZEOF(INT32));
nuclear@26:   upsample->Cb_g_tab = (INT32 *)
nuclear@26:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26: 				(MAXJSAMPLE+1) * SIZEOF(INT32));
nuclear@26: 
nuclear@26:   for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
nuclear@26:     /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
nuclear@26:     /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
nuclear@26:     /* Cr=>R value is nearest int to 1.40200 * x */
nuclear@26:     upsample->Cr_r_tab[i] = (int)
nuclear@26: 		    RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
nuclear@26:     /* Cb=>B value is nearest int to 1.77200 * x */
nuclear@26:     upsample->Cb_b_tab[i] = (int)
nuclear@26: 		    RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
nuclear@26:     /* Cr=>G value is scaled-up -0.71414 * x */
nuclear@26:     upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x;
nuclear@26:     /* Cb=>G value is scaled-up -0.34414 * x */
nuclear@26:     /* We also add in ONE_HALF so that need not do it in inner loop */
nuclear@26:     upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
nuclear@26:   }
nuclear@26: }
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * Initialize for an upsampling pass.
nuclear@26:  */
nuclear@26: 
nuclear@26: METHODDEF(void)
nuclear@26: start_pass_merged_upsample (j_decompress_ptr cinfo)
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26: 
nuclear@26:   /* Mark the spare buffer empty */
nuclear@26:   upsample->spare_full = FALSE;
nuclear@26:   /* Initialize total-height counter for detecting bottom of image */
nuclear@26:   upsample->rows_to_go = cinfo->output_height;
nuclear@26: }
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * Control routine to do upsampling (and color conversion).
nuclear@26:  *
nuclear@26:  * The control routine just handles the row buffering considerations.
nuclear@26:  */
nuclear@26: 
nuclear@26: METHODDEF(void)
nuclear@26: merged_2v_upsample (j_decompress_ptr cinfo,
nuclear@26: 		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26: 		    JDIMENSION in_row_groups_avail,
nuclear@26: 		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26: 		    JDIMENSION out_rows_avail)
nuclear@26: /* 2:1 vertical sampling case: may need a spare row. */
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26:   JSAMPROW work_ptrs[2];
nuclear@26:   JDIMENSION num_rows;		/* number of rows returned to caller */
nuclear@26: 
nuclear@26:   if (upsample->spare_full) {
nuclear@26:     /* If we have a spare row saved from a previous cycle, just return it. */
nuclear@26:     jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
nuclear@26: 		      1, upsample->out_row_width);
nuclear@26:     num_rows = 1;
nuclear@26:     upsample->spare_full = FALSE;
nuclear@26:   } else {
nuclear@26:     /* Figure number of rows to return to caller. */
nuclear@26:     num_rows = 2;
nuclear@26:     /* Not more than the distance to the end of the image. */
nuclear@26:     if (num_rows > upsample->rows_to_go)
nuclear@26:       num_rows = upsample->rows_to_go;
nuclear@26:     /* And not more than what the client can accept: */
nuclear@26:     out_rows_avail -= *out_row_ctr;
nuclear@26:     if (num_rows > out_rows_avail)
nuclear@26:       num_rows = out_rows_avail;
nuclear@26:     /* Create output pointer array for upsampler. */
nuclear@26:     work_ptrs[0] = output_buf[*out_row_ctr];
nuclear@26:     if (num_rows > 1) {
nuclear@26:       work_ptrs[1] = output_buf[*out_row_ctr + 1];
nuclear@26:     } else {
nuclear@26:       work_ptrs[1] = upsample->spare_row;
nuclear@26:       upsample->spare_full = TRUE;
nuclear@26:     }
nuclear@26:     /* Now do the upsampling. */
nuclear@26:     (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);
nuclear@26:   }
nuclear@26: 
nuclear@26:   /* Adjust counts */
nuclear@26:   *out_row_ctr += num_rows;
nuclear@26:   upsample->rows_to_go -= num_rows;
nuclear@26:   /* When the buffer is emptied, declare this input row group consumed */
nuclear@26:   if (! upsample->spare_full)
nuclear@26:     (*in_row_group_ctr)++;
nuclear@26: }
nuclear@26: 
nuclear@26: 
nuclear@26: METHODDEF(void)
nuclear@26: merged_1v_upsample (j_decompress_ptr cinfo,
nuclear@26: 		    JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
nuclear@26: 		    JDIMENSION in_row_groups_avail,
nuclear@26: 		    JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
nuclear@26: 		    JDIMENSION out_rows_avail)
nuclear@26: /* 1:1 vertical sampling case: much easier, never need a spare row. */
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26: 
nuclear@26:   /* Just do the upsampling. */
nuclear@26:   (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,
nuclear@26: 			 output_buf + *out_row_ctr);
nuclear@26:   /* Adjust counts */
nuclear@26:   (*out_row_ctr)++;
nuclear@26:   (*in_row_group_ctr)++;
nuclear@26: }
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * These are the routines invoked by the control routines to do
nuclear@26:  * the actual upsampling/conversion.  One row group is processed per call.
nuclear@26:  *
nuclear@26:  * Note: since we may be writing directly into application-supplied buffers,
nuclear@26:  * we have to be honest about the output width; we can't assume the buffer
nuclear@26:  * has been rounded up to an even width.
nuclear@26:  */
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
nuclear@26:  */
nuclear@26: 
nuclear@26: METHODDEF(void)
nuclear@26: h2v1_merged_upsample (j_decompress_ptr cinfo,
nuclear@26: 		      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
nuclear@26: 		      JSAMPARRAY output_buf)
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26:   register int y, cred, cgreen, cblue;
nuclear@26:   int cb, cr;
nuclear@26:   register JSAMPROW outptr;
nuclear@26:   JSAMPROW inptr0, inptr1, inptr2;
nuclear@26:   JDIMENSION col;
nuclear@26:   /* copy these pointers into registers if possible */
nuclear@26:   register JSAMPLE * range_limit = cinfo->sample_range_limit;
nuclear@26:   int * Crrtab = upsample->Cr_r_tab;
nuclear@26:   int * Cbbtab = upsample->Cb_b_tab;
nuclear@26:   INT32 * Crgtab = upsample->Cr_g_tab;
nuclear@26:   INT32 * Cbgtab = upsample->Cb_g_tab;
nuclear@26:   SHIFT_TEMPS
nuclear@26: 
nuclear@26:   inptr0 = input_buf[0][in_row_group_ctr];
nuclear@26:   inptr1 = input_buf[1][in_row_group_ctr];
nuclear@26:   inptr2 = input_buf[2][in_row_group_ctr];
nuclear@26:   outptr = output_buf[0];
nuclear@26:   /* Loop for each pair of output pixels */
nuclear@26:   for (col = cinfo->output_width >> 1; col > 0; col--) {
nuclear@26:     /* Do the chroma part of the calculation */
nuclear@26:     cb = GETJSAMPLE(*inptr1++);
nuclear@26:     cr = GETJSAMPLE(*inptr2++);
nuclear@26:     cred = Crrtab[cr];
nuclear@26:     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
nuclear@26:     cblue = Cbbtab[cb];
nuclear@26:     /* Fetch 2 Y values and emit 2 pixels */
nuclear@26:     y  = GETJSAMPLE(*inptr0++);
nuclear@26:     outptr[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     outptr += RGB_PIXELSIZE;
nuclear@26:     y  = GETJSAMPLE(*inptr0++);
nuclear@26:     outptr[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     outptr += RGB_PIXELSIZE;
nuclear@26:   }
nuclear@26:   /* If image width is odd, do the last output column separately */
nuclear@26:   if (cinfo->output_width & 1) {
nuclear@26:     cb = GETJSAMPLE(*inptr1);
nuclear@26:     cr = GETJSAMPLE(*inptr2);
nuclear@26:     cred = Crrtab[cr];
nuclear@26:     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
nuclear@26:     cblue = Cbbtab[cb];
nuclear@26:     y  = GETJSAMPLE(*inptr0);
nuclear@26:     outptr[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:   }
nuclear@26: }
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
nuclear@26:  */
nuclear@26: 
nuclear@26: METHODDEF(void)
nuclear@26: h2v2_merged_upsample (j_decompress_ptr cinfo,
nuclear@26: 		      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
nuclear@26: 		      JSAMPARRAY output_buf)
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
nuclear@26:   register int y, cred, cgreen, cblue;
nuclear@26:   int cb, cr;
nuclear@26:   register JSAMPROW outptr0, outptr1;
nuclear@26:   JSAMPROW inptr00, inptr01, inptr1, inptr2;
nuclear@26:   JDIMENSION col;
nuclear@26:   /* copy these pointers into registers if possible */
nuclear@26:   register JSAMPLE * range_limit = cinfo->sample_range_limit;
nuclear@26:   int * Crrtab = upsample->Cr_r_tab;
nuclear@26:   int * Cbbtab = upsample->Cb_b_tab;
nuclear@26:   INT32 * Crgtab = upsample->Cr_g_tab;
nuclear@26:   INT32 * Cbgtab = upsample->Cb_g_tab;
nuclear@26:   SHIFT_TEMPS
nuclear@26: 
nuclear@26:   inptr00 = input_buf[0][in_row_group_ctr*2];
nuclear@26:   inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
nuclear@26:   inptr1 = input_buf[1][in_row_group_ctr];
nuclear@26:   inptr2 = input_buf[2][in_row_group_ctr];
nuclear@26:   outptr0 = output_buf[0];
nuclear@26:   outptr1 = output_buf[1];
nuclear@26:   /* Loop for each group of output pixels */
nuclear@26:   for (col = cinfo->output_width >> 1; col > 0; col--) {
nuclear@26:     /* Do the chroma part of the calculation */
nuclear@26:     cb = GETJSAMPLE(*inptr1++);
nuclear@26:     cr = GETJSAMPLE(*inptr2++);
nuclear@26:     cred = Crrtab[cr];
nuclear@26:     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
nuclear@26:     cblue = Cbbtab[cb];
nuclear@26:     /* Fetch 4 Y values and emit 4 pixels */
nuclear@26:     y  = GETJSAMPLE(*inptr00++);
nuclear@26:     outptr0[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr0[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr0[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     outptr0 += RGB_PIXELSIZE;
nuclear@26:     y  = GETJSAMPLE(*inptr00++);
nuclear@26:     outptr0[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr0[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr0[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     outptr0 += RGB_PIXELSIZE;
nuclear@26:     y  = GETJSAMPLE(*inptr01++);
nuclear@26:     outptr1[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr1[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr1[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     outptr1 += RGB_PIXELSIZE;
nuclear@26:     y  = GETJSAMPLE(*inptr01++);
nuclear@26:     outptr1[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr1[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr1[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     outptr1 += RGB_PIXELSIZE;
nuclear@26:   }
nuclear@26:   /* If image width is odd, do the last output column separately */
nuclear@26:   if (cinfo->output_width & 1) {
nuclear@26:     cb = GETJSAMPLE(*inptr1);
nuclear@26:     cr = GETJSAMPLE(*inptr2);
nuclear@26:     cred = Crrtab[cr];
nuclear@26:     cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
nuclear@26:     cblue = Cbbtab[cb];
nuclear@26:     y  = GETJSAMPLE(*inptr00);
nuclear@26:     outptr0[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr0[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr0[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:     y  = GETJSAMPLE(*inptr01);
nuclear@26:     outptr1[RGB_RED] =   range_limit[y + cred];
nuclear@26:     outptr1[RGB_GREEN] = range_limit[y + cgreen];
nuclear@26:     outptr1[RGB_BLUE] =  range_limit[y + cblue];
nuclear@26:   }
nuclear@26: }
nuclear@26: 
nuclear@26: 
nuclear@26: /*
nuclear@26:  * Module initialization routine for merged upsampling/color conversion.
nuclear@26:  *
nuclear@26:  * NB: this is called under the conditions determined by use_merged_upsample()
nuclear@26:  * in jdmaster.c.  That routine MUST correspond to the actual capabilities
nuclear@26:  * of this module; no safety checks are made here.
nuclear@26:  */
nuclear@26: 
nuclear@26: GLOBAL(void)
nuclear@26: jinit_merged_upsampler (j_decompress_ptr cinfo)
nuclear@26: {
nuclear@26:   my_upsample_ptr upsample;
nuclear@26: 
nuclear@26:   upsample = (my_upsample_ptr)
nuclear@26:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26: 				SIZEOF(my_upsampler));
nuclear@26:   cinfo->upsample = (struct jpeg_upsampler *) upsample;
nuclear@26:   upsample->pub.start_pass = start_pass_merged_upsample;
nuclear@26:   upsample->pub.need_context_rows = FALSE;
nuclear@26: 
nuclear@26:   upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
nuclear@26: 
nuclear@26:   if (cinfo->max_v_samp_factor == 2) {
nuclear@26:     upsample->pub.upsample = merged_2v_upsample;
nuclear@26:     upsample->upmethod = h2v2_merged_upsample;
nuclear@26:     /* Allocate a spare row buffer */
nuclear@26:     upsample->spare_row = (JSAMPROW)
nuclear@26:       (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@26: 		(size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
nuclear@26:   } else {
nuclear@26:     upsample->pub.upsample = merged_1v_upsample;
nuclear@26:     upsample->upmethod = h2v1_merged_upsample;
nuclear@26:     /* No spare row needed */
nuclear@26:     upsample->spare_row = NULL;
nuclear@26:   }
nuclear@26: 
nuclear@26:   build_ycc_rgb_table(cinfo);
nuclear@26: }
nuclear@26: 
nuclear@26: #endif /* UPSAMPLE_MERGING_SUPPORTED */