yuv2rgb.c

H.263的压缩算法

/************************************************************************
 *
 *  yuv2rgb.c, colour space conversion for tmndecode (H.263 decoder)
 *  Copyright (C) 1995, 1996  Telenor R&D, Norway
 *
 *  Contacts:
 *  Robert Danielsen                  <[e-mail]>
 *
 *  Telenor Research and Development  http://www.nta.no/brukere/DVC/
 *  P.O.Box 83                        tel.:   [phone]
 *  N-2007 Kjeller, Norway            fax.:   [phone]
 *
 *  Copyright (C) 1997  University of BC, Canada
 *  Modified by: Michael Gallant <[e-mail]>
 *               Guy Cote <[e-mail]>
 *               Berna Erol <[e-mail]>
 *
 *  Contacts:
 *  Michael Gallant                   <[e-mail]>
 *
 *  UBC Image Processing Laboratory   http://www.ee.ubc.ca/image
 *  2356 Main Mall                    tel.: [phone]
 *  Vancouver BC Canada V6T1Z4        fax.: [phone]
 *
 ************************************************************************/

/* Disclaimer of Warranty
 * 
 * These software programs are available to the user without any license fee
 * or royalty on an "as is" basis. The University of British Columbia
 * disclaims any and all warranties, whether express, implied, or
 * statuary, including any implied warranties or merchantability or of
 * fitness for a particular purpose.  In no event shall the
 * copyright-holder be liable for any incidental, punitive, or
 * consequential damages of any kind whatsoever arising from the use of
 * these programs.
 * 
 * This disclaimer of warranty extends to the user of these programs and
 * user's customers, employees, agents, transferees, successors, and
 * assigns.
 * 
 * The University of British Columbia does not represent or warrant that the
 * programs furnished hereunder are free of infringement of any
 * third-party patents.
 * 
 * Commercial implementations of H.263, including shareware, are subject to
 * royalty fees to patent holders.  Many of these patents are general
 * enough such that they are unavoidable regardless of implementation
 * design.
 * 
 */


/* Copyright (c) 1995 Erik Corry All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written
 * agreement is hereby granted, provided that the above copyright notice
 * and the following two paragraphs appear in all copies of this software.
 * 
 * IN NO EVENT SHALL ERIK CORRY BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
 * SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF
 * THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF ERIK CORRY HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * ERIK CORRY SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
 * BASIS, AND ERIK CORRY HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
 * SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. */


#include "config.h"
#include "tmndec.h"
#include "global.h"

#ifdef DISPLAY
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#endif


#ifdef DISPLAY

#undef INTERPOLATE

/* Erik Corry's multi-byte dither routines.
 * 
 * The basic idea is that the Init generates all the necessary tables. The
 * tables incorporate the information about the layout of pixels in the
 * XImage, so that it should be able to cope with 15-bit, 16-bit 24-bit
 * (non-packed) and 32-bit (10-11 bits per color!) screens. At present it
 * cannot cope with 24-bit packed mode, since this involves getting down
 * to byte level again. It is assumed that the bits for each color are
 * contiguous in the longword.
 * 
 * Writing to memory is done in shorts or ints. (Unfortunately, short is not
 * very fast on Alpha, so there is room for improvement here). There is no
 * dither time check for overflow - instead the tables have slack at each
 * end. This is likely to be faster than an 'if' test as many modern
 * architectures are really bad at ifs. Potentially, each '&&' causes a
 * pipeline flush!
 * 
 * There is no shifting and fixed point arithmetic, as I really doubt you can
 * see the difference, and it costs. This may be just my bias, since I
 * heard that Intel is really bad at shifting. */

/* Gamma correction stuff */

#define GAMMA_CORRECTION(x) ((int)(pow((x) / 255.0, 1.0 / gammaCorrect) * 255.0))
#define CHROMA_CORRECTION256(x) ((x) >= 128 \
                    ? 128 + mmin(127, (int)(((x) - 128.0) * chromaCorrect)) \
                    : 128 - mmin(128, (int)((128.0 - (x)) * chromaCorrect)))
#define CHROMA_CORRECTION128(x) ((x) >= 0 \
                    ? mmin(127,  (int)(((x) * chromaCorrect))) \
                    : mmax(-128, (int)(((x) * chromaCorrect))))
#define CHROMA_CORRECTION256D(x) ((x) >= 128 \
                    ? 128.0 + mmin(127.0, (((x) - 128.0) * chromaCorrect)) \
                    : 128.0 - mmin(128.0, (((128.0 - (x)) * chromaCorrect))))
#define CHROMA_CORRECTION128D(x) ((x) >= 0 \
                    ? mmin(127.0,  ((x) * chromaCorrect)) \
                    : mmax(-128.0, ((x) * chromaCorrect)))


/* Flag for gamma correction */
int gammaCorrectFlag = 0;
double gammaCorrect = 1.0;

/* Flag for chroma correction */
int chromaCorrectFlag = 0;
double chromaCorrect = 1.0;

/* How many 1 bits are there in the longword. Low performance, do not call
 * often. */
static int
 number_of_bits_set (a)
  unsigned long a;
{
  if (!a)
    return 0;
  if (a & 1)
    return 1 + number_of_bits_set (a >> 1);
  return (number_of_bits_set (a >> 1));
}

/* Shift the 0s in the least significant end out of the longword. Low
 * performance, do not call often. */
static unsigned long
 shifted_down (a)
  unsigned long a;
{
  if (!a)
    return 0;
  if (a & 1)
    return a;
  return a >> 1;
}

/* How many 0 bits are there at most significant end of longword. Low
 * performance, do not call often. */
static int
 free_bits_at_top (a)
  unsigned long a;
{
  /* assume char is 8 bits */
  if (!a)
    return sizeof (unsigned long) * 8;
  /* assume twos complement */
  if (((long) a) < 0l)
    return 0;
  return 1 + free_bits_at_top (a << 1);
}

/* How many 0 bits are there at least significant end of longword. Low
 * performance, do not call often. */
static int
 free_bits_at_bottom (a)
  unsigned long a;
{
  /* assume char is 8 bits */
  if (!a)
    return sizeof (unsigned long) * 8;
  if (((long) a) & 1l)
    return 0;
  return 1 + free_bits_at_bottom (a >> 1);
}

static int *L_tab, *Cr_r_tab, *Cr_g_tab, *Cb_g_tab, *Cb_b_tab;

/* We define tables that convert a color value between -256 and 512 into
 * the R, G and B parts of the pixel. The normal range is 0-255. */

static long *r_2_pix;
static long *g_2_pix;
static long *b_2_pix;
static long *r_2_pix_alloc;
static long *g_2_pix_alloc;
static long *b_2_pix_alloc;




/* --------------------------------------------------------------
 * 
 * InitColor16Dither --
 * 
 * To get rid of the multiply and other conversions in color dither, we use a
 * lookup table.
 * 
 * Results: None.
 * 
 * Side effects: The lookup tables are initialized.
 * 
 * -------------------------------------------------------------- */

void
 InitColorDither (thirty2)
  int thirty2;
{
  extern XImage *ximage;
  extern unsigned long wpixel[3];
  /* misuse of the wpixel array for the pixel masks. Note that this
   * implies that the window is created before this routine is called */


  unsigned long red_mask = wpixel[0];
  unsigned long green_mask = wpixel[1];
  unsigned long blue_mask = wpixel[2];

  int CR, CB, i;

  if (ximage->bits_per_pixel == 24) /* not necessary in non-packed mode */
    init_dither_tab ();

  L_tab = (int *) malloc (256 * sizeof (int));
  Cr_r_tab = (int *) malloc (256 * sizeof (int));
  Cr_g_tab = (int *) malloc (256 * sizeof (int));
  Cb_g_tab = (int *) malloc (256 * sizeof (int));
  Cb_b_tab = (int *) malloc (256 * sizeof (int));

  r_2_pix_alloc = (long *) malloc (768 * sizeof (long));
  g_2_pix_alloc = (long *) malloc (768 * sizeof (long));
  b_2_pix_alloc = (long *) malloc (768 * sizeof (long));

  if (L_tab == NULL ||
      Cr_r_tab == NULL ||
      Cr_g_tab == NULL ||
      Cb_g_tab == NULL ||
      Cb_b_tab == NULL ||
      r_2_pix_alloc == NULL ||
      g_2_pix_alloc == NULL ||
      b_2_pix_alloc == NULL)
  {
    fprintf (stderr, "Could not get enough memory in InitColorDither\n");
    exit (1);
  }
  for (i = 0; i < 256; i++)
  {
    L_tab[i] = i;
    if (gammaCorrectFlag)
    {
      L_tab[i] = GAMMA_CORRECTION (i);
    }
    CB = CR = i;

    if (chromaCorrectFlag)
    {
      CB -= 128;
      CB = CHROMA_CORRECTION128 (CB);
      CR -= 128;
      CR = CHROMA_CORRECTION128 (CR);
    } else
    {
      CB -= 128;
      CR -= 128;
    }
    /* was Cr_r_tab[i] =  1.596 * CR; Cr_g_tab[i] = -0.813 * CR;
     * Cb_g_tab[i] = -0.391 * CB;   Cb_b_tab[i] =  2.018 * CB; but they
     * were just messed up. Then was (_Video Deymstified_): Cr_r_tab[i] =
     * 1.366 * CR; Cr_g_tab[i] = -0.700 * CR; Cb_g_tab[i] = -0.334 * CB;
     * Cb_b_tab[i] =  1.732 * CB; but really should be: (from ITU-R
     * BT.470-2 System B, G and SMPTE 170M ) */
    Cr_r_tab[i] = (0.419 / 0.299) * CR;
    Cr_g_tab[i] = -(0.299 / 0.419) * CR;
    Cb_g_tab[i] = -(0.114 / 0.331) * CB;
    Cb_b_tab[i] = (0.587 / 0.331) * CB;

    /* though you could argue for: SMPTE 240M Cr_r_tab[i] =  (0.445/0.212) *
     * CR; Cr_g_tab[i] = -(0.212/0.445) * CR; Cb_g_tab[i] = -(0.087/0.384) *
     * CB; Cb_b_tab[i] =  (0.701/0.384) * CB; FCC Cr_r_tab[i] =
     * (0.421/0.30) * CR; Cr_g_tab[i] = -(0.30/0.421) * CR; Cb_g_tab[i] =
     * -(0.11/0.331) * CB; Cb_b_tab[i] =  (0.59/0.331) * CB; ITU-R BT.709
     * Cr_r_tab[i] =  (0.454/0.2125) * CR; Cr_g_tab[i] = -(0.2125/0.454) *
     * CR; Cb_g_tab[i] = -(0.0721/0.386) * CB; Cb_b_tab[i] =
     * (0.7154/0.386) * CB; */
  }

  /* Set up entries 0-255 in rgb-to-pixel value tables. */
  for (i = 0; i < 256; i++)
  {
    r_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set (red_mask));
    r_2_pix_alloc[i + 256] <<= free_bits_at_bottom (red_mask);
    g_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set (green_mask));
    g_2_pix_alloc[i + 256] <<= free_bits_at_bottom (green_mask);