modules/video_chroma/i420_rgb.c

   1 /*****************************************************************************
   2  * i420_rgb.c : YUV to bitmap RGB conversion module for vlc
   3  *****************************************************************************
   4  * Copyright (C) 2000, 2001, 2004, 2008 the VideoLAN team
   5  * $Id$
   6  *
   7  * Authors: Sam Hocevar <sam@zoy.org>
   8  *          Damien Fouilleul <damienf@videolan.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  23  *****************************************************************************/
  24
  25 /*****************************************************************************
  26  * Preamble
  27  *****************************************************************************/
  28
  29 #ifdef HAVE_CONFIG_H
  30 # include "config.h"
  31 #endif
  32
  33 #include <math.h>                                            /* exp(), pow() */
  34
  35 #include <vlc_common.h>
  36 #include <vlc_plugin.h>
  37 #include <vlc_filter.h>
  38
  39 #include "i420_rgb.h"
  40 #if defined (MODULE_NAME_IS_i420_rgb)
  41 #   include "i420_rgb_c.h"
  42     static picture_t *I420_RGB8_Filter         ( filter_t *, picture_t * );
  43 //    static picture_t *I420_RGB16_dither_Filter ( filter_t *, picture_t * );
  44     static picture_t *I420_RGB16_Filter        ( filter_t *, picture_t * );
  45     static picture_t *I420_RGB32_Filter        ( filter_t *, picture_t * );
  46 #else
  47     static picture_t *I420_R5G5B5_Filter       ( filter_t *, picture_t * );
  48     static picture_t *I420_R5G6B5_Filter       ( filter_t *, picture_t * );
  49     static picture_t *I420_A8R8G8B8_Filter     ( filter_t *, picture_t * );
  50     static picture_t *I420_R8G8B8A8_Filter     ( filter_t *, picture_t * );
  51     static picture_t *I420_B8G8R8A8_Filter     ( filter_t *, picture_t * );
  52     static picture_t *I420_A8B8G8R8_Filter     ( filter_t *, picture_t * );
  53 #endif
  54
  55 /*****************************************************************************
  56  * RGB2PIXEL: assemble RGB components to a pixel value, returns a uint32_t
  57  *****************************************************************************/
  58 #define RGB2PIXEL( p_filter, i_r, i_g, i_b )                 \
  59     (((((uint32_t)i_r) >> p_filter->fmt_out.video.i_rrshift) \
  60                        << p_filter->fmt_out.video.i_lrshift) \
  61    | ((((uint32_t)i_g) >> p_filter->fmt_out.video.i_rgshift) \
  62                        << p_filter->fmt_out.video.i_lgshift) \
  63    | ((((uint32_t)i_b) >> p_filter->fmt_out.video.i_rbshift) \
  64                        << p_filter->fmt_out.video.i_lbshift))
  65
  66 /*****************************************************************************
  67  * Local and extern prototypes.
  68  *****************************************************************************/
  69 static int  Activate   ( vlc_object_t * );
  70 static void Deactivate ( vlc_object_t * );
  71
  72 #if defined (MODULE_NAME_IS_i420_rgb)
  73 static void SetGammaTable       ( int *pi_table, double f_gamma );
  74 static void SetYUV              ( filter_t * );
  75 static void Set8bppPalette      ( filter_t *, uint8_t * );
  76 #endif
  77
  78 /*****************************************************************************
  79  * Module descriptor.
  80  *****************************************************************************/
  81 vlc_module_begin ()
  82 #if defined (MODULE_NAME_IS_i420_rgb)
  83     set_description( N_("I420,IYUV,YV12 to "
  84                        "RGB2,RV15,RV16,RV24,RV32 conversions") )
  85     set_capability( "video filter2", 80 )
  86 #elif defined (MODULE_NAME_IS_i420_rgb_mmx)
  87     set_description( N_( "MMX I420,IYUV,YV12 to "
  88                         "RV15,RV16,RV24,RV32 conversions") )
  89     set_capability( "video filter2", 100 )
  90 #elif defined (MODULE_NAME_IS_i420_rgb_sse2)
  91     set_description( N_( "SSE2 I420,IYUV,YV12 to "
  92                         "RV15,RV16,RV24,RV32 conversions") )
  93     set_capability( "video filter2", 120 )
  94 #endif
  95     set_callbacks( Activate, Deactivate )
  96 vlc_module_end ()
  97
  98 /*****************************************************************************
  99  * Activate: allocate a chroma function
 100  *****************************************************************************
 101  * This function allocates and initializes a chroma function
 102  *****************************************************************************/
 103 static int Activate( vlc_object_t *p_this )
 104 {
 105     filter_t *p_filter = (filter_t *)p_this;
 106 #if defined (MODULE_NAME_IS_i420_rgb)
 107     size_t i_tables_size;
 108 #endif
 109
 110     if( p_filter->fmt_out.video.i_width & 1
 111      || p_filter->fmt_out.video.i_height & 1 )
 112     {
 113         return VLC_EGENERIC;
 114     }
 115
 116     switch( p_filter->fmt_in.video.i_chroma )
 117     {
 118         case VLC_CODEC_YV12:
 119         case VLC_CODEC_I420:
 120             switch( p_filter->fmt_out.video.i_chroma )
 121             {
 122 #if defined (MODULE_NAME_IS_i420_rgb)
 123                 case VLC_CODEC_RGB8:
 124                     p_filter->pf_video_filter = I420_RGB8_Filter;
 125                     break;
 126 #endif
 127                 case VLC_CODEC_RGB15:
 128                 case VLC_CODEC_RGB16:
 129 #if ! defined (MODULE_NAME_IS_i420_rgb)
 130                     /* If we don't have support for the bitmasks, bail out */
 131                     if( ( p_filter->fmt_out.video.i_rmask == 0x7c00
 132                        && p_filter->fmt_out.video.i_gmask == 0x03e0
 133                        && p_filter->fmt_out.video.i_bmask == 0x001f ) )
 134                     {
 135                         /* R5G5B6 pixel format */
 136                         msg_Dbg(p_this, "RGB pixel format is R5G5B5");
 137                         p_filter->pf_video_filter = I420_R5G5B5_Filter;
 138                     }
 139                     else if( ( p_filter->fmt_out.video.i_rmask == 0xf800
 140                             && p_filter->fmt_out.video.i_gmask == 0x07e0
 141                             && p_filter->fmt_out.video.i_bmask == 0x001f ) )
 142                     {
 143                         /* R5G6B5 pixel format */
 144                         msg_Dbg(p_this, "RGB pixel format is R5G6B5");
 145                         p_filter->pf_video_filter = I420_R5G6B5_Filter;
 146                     }
 147                     else
 148                         return VLC_EGENERIC;
 149 #else
 150                     // generic C chroma converter */
 151                     p_filter->pf_video_filter = I420_RGB16_Filter;
 152 #endif
 153                     break;
 154
 155 #if 0
 156                 /* Hmmm, is there only X11 using 32bits per pixel for RV24 ? */
 157                 case VLC_CODEC_RGB24:
 158 #endif
 159
 160                 case VLC_CODEC_RGB32:
 161 #if ! defined (MODULE_NAME_IS_i420_rgb)
 162                     /* If we don't have support for the bitmasks, bail out */
 163                     if( p_filter->fmt_out.video.i_rmask == 0x00ff0000
 164                      && p_filter->fmt_out.video.i_gmask == 0x0000ff00
 165                      && p_filter->fmt_out.video.i_bmask == 0x000000ff )
 166                     {
 167                         /* A8R8G8B8 pixel format */
 168                         msg_Dbg(p_this, "RGB pixel format is A8R8G8B8");
 169                         p_filter->pf_video_filter = I420_A8R8G8B8_Filter;
 170                     }
 171                     else if( p_filter->fmt_out.video.i_rmask == 0xff000000
 172                           && p_filter->fmt_out.video.i_gmask == 0x00ff0000
 173                           && p_filter->fmt_out.video.i_bmask == 0x0000ff00 )
 174                     {
 175                         /* R8G8B8A8 pixel format */
 176                         msg_Dbg(p_this, "RGB pixel format is R8G8B8A8");
 177                         p_filter->pf_video_filter = I420_R8G8B8A8_Filter;
 178                     }
 179                     else if( p_filter->fmt_out.video.i_rmask == 0x0000ff00
 180                           && p_filter->fmt_out.video.i_gmask == 0x00ff0000
 181                           && p_filter->fmt_out.video.i_bmask == 0xff000000 )
 182                     {
 183                         /* B8G8R8A8 pixel format */
 184                         msg_Dbg(p_this, "RGB pixel format is B8G8R8A8");
 185                         p_filter->pf_video_filter = I420_B8G8R8A8_Filter;
 186                     }
 187                     else if( p_filter->fmt_out.video.i_rmask == 0x000000ff
 188                           && p_filter->fmt_out.video.i_gmask == 0x0000ff00
 189                           && p_filter->fmt_out.video.i_bmask == 0x00ff0000 )
 190                     {
 191                         /* A8B8G8R8 pixel format */
 192                         msg_Dbg(p_this, "RGB pixel format is A8B8G8R8");
 193                         p_filter->pf_video_filter = I420_A8B8G8R8_Filter;
 194                     }
 195                     else
 196                         return VLC_EGENERIC;
 197 #else
 198                     /* generic C chroma converter */
 199                     p_filter->pf_video_filter = I420_RGB32_Filter;
 200 #endif
 201                     break;
 202
 203                 default:
 204                     return VLC_EGENERIC;
 205             }
 206             break;
 207
 208         default:
 209             return VLC_EGENERIC;
 210     }
 211
 212     p_filter->p_sys = malloc( sizeof( filter_sys_t ) );
 213     if( p_filter->p_sys == NULL )
 214     {
 215         return VLC_EGENERIC;
 216     }
 217
 218     switch( p_filter->fmt_out.video.i_chroma )
 219     {
 220 #if defined (MODULE_NAME_IS_i420_rgb)
 221         case VLC_CODEC_RGB8:
 222             p_filter->p_sys->p_buffer = malloc( VOUT_MAX_WIDTH );
 223             break;
 224 #endif
 225
 226         case VLC_CODEC_RGB15:
 227         case VLC_CODEC_RGB16:
 228             p_filter->p_sys->p_buffer = malloc( VOUT_MAX_WIDTH * 2 );
 229             break;
 230
 231         case VLC_CODEC_RGB24:
 232         case VLC_CODEC_RGB32:
 233             p_filter->p_sys->p_buffer = malloc( VOUT_MAX_WIDTH * 4 );
 234             break;
 235
 236         default:
 237             p_filter->p_sys->p_buffer = NULL;
 238             break;
 239     }
 240
 241     if( p_filter->p_sys->p_buffer == NULL )
 242     {
 243         free( p_filter->p_sys );
 244         return VLC_EGENERIC;
 245     }
 246
 247     p_filter->p_sys->p_offset = malloc( p_filter->fmt_out.video.i_width
 248                     * ( ( p_filter->fmt_out.video.i_chroma
 249                            == VLC_CODEC_RGB8 ) ? 2 : 1 )
 250                     * sizeof( int ) );
 251     if( p_filter->p_sys->p_offset == NULL )
 252     {
 253         free( p_filter->p_sys->p_buffer );
 254         free( p_filter->p_sys );
 255         return VLC_EGENERIC;
 256     }
 257
 258 #if defined (MODULE_NAME_IS_i420_rgb)
 259     switch( p_filter->fmt_out.video.i_chroma )
 260     {
 261     case VLC_CODEC_RGB8:
 262         i_tables_size = sizeof( uint8_t ) * PALETTE_TABLE_SIZE;
 263         break;
 264     case VLC_CODEC_RGB15:
 265     case VLC_CODEC_RGB16:
 266         i_tables_size = sizeof( uint16_t ) * RGB_TABLE_SIZE;
 267         break;
 268     default: /* RV24, RV32 */
 269         i_tables_size = sizeof( uint32_t ) * RGB_TABLE_SIZE;
 270         break;
 271     }
 272
 273     p_filter->p_sys->p_base = malloc( i_tables_size );
 274     if( p_filter->p_sys->p_base == NULL )
 275     {
 276         free( p_filter->p_sys->p_offset );
 277         free( p_filter->p_sys->p_buffer );
 278         free( p_filter->p_sys );
 279         return -1;
 280     }
 281
 282     SetYUV( p_filter );
 283 #endif
 284
 285     return 0;
 286 }
 287
 288 /*****************************************************************************
 289  * Deactivate: free the chroma function
 290  *****************************************************************************
 291  * This function frees the previously allocated chroma function
 292  *****************************************************************************/
 293 static void Deactivate( vlc_object_t *p_this )
 294 {
 295     filter_t *p_filter = (filter_t *)p_this;
 296
 297 #if defined (MODULE_NAME_IS_i420_rgb)
 298     free( p_filter->p_sys->p_base );
 299 #endif
 300     free( p_filter->p_sys->p_offset );
 301     free( p_filter->p_sys->p_buffer );
 302     free( p_filter->p_sys );
 303 }
 304
 305 #if defined (MODULE_NAME_IS_i420_rgb)
 306 VIDEO_FILTER_WRAPPER( I420_RGB8 )
 307 VIDEO_FILTER_WRAPPER( I420_RGB16 )
 308 //VIDEO_FILTER_WRAPPER( I420_RGB16_dither )
 309 VIDEO_FILTER_WRAPPER( I420_RGB32 )
 310 #else
 311 VIDEO_FILTER_WRAPPER( I420_R5G5B5 )
 312 VIDEO_FILTER_WRAPPER( I420_R5G6B5 )
 313 VIDEO_FILTER_WRAPPER( I420_A8R8G8B8 )
 314 VIDEO_FILTER_WRAPPER( I420_R8G8B8A8 )
 315 VIDEO_FILTER_WRAPPER( I420_B8G8R8A8 )
 316 VIDEO_FILTER_WRAPPER( I420_A8B8G8R8 )
 317 #endif
 318
 319 #if defined (MODULE_NAME_IS_i420_rgb)
 320 /*****************************************************************************
 321  * SetGammaTable: return intensity table transformed by gamma curve.
 322  *****************************************************************************
 323  * pi_table is a table of 256 entries from 0 to 255.
 324  *****************************************************************************/
 325 static void SetGammaTable( int *pi_table, double f_gamma )
 326 {
 327     int i_y;                                               /* base intensity */
 328
 329     /* Use exp(gamma) instead of gamma */
 330     f_gamma = exp( f_gamma );
 331
 332     /* Build gamma table */
 333     for( i_y = 0; i_y < 256; i_y++ )
 334     {
 335         pi_table[ i_y ] = (int)( pow( (double)i_y / 256, f_gamma ) * 256 );
 336     }
 337 }
 338
 339 /*****************************************************************************
 340  * SetYUV: compute tables and set function pointers
 341  *****************************************************************************/
 342 static void SetYUV( filter_t *p_filter )
 343 {
 344     int          pi_gamma[256];                               /* gamma table */
 345     volatile int i_index;                                 /* index in tables */
 346                    /* We use volatile here to work around a strange gcc-3.3.4
 347                     * optimization bug */
 348
 349     /* Build gamma table */
 350     SetGammaTable( pi_gamma, 0 ); //p_filter/*FIXME wasn't used anywhere anyway*/->f_gamma );
 351
 352     /*
 353      * Set pointers and build YUV tables
 354      */
 355
 356     /* Color: build red, green and blue tables */
 357     switch( p_filter->fmt_out.video.i_chroma )
 358     {
 359     case VLC_CODEC_RGB8:
 360         p_filter->p_sys->p_rgb8 = (uint8_t *)p_filter->p_sys->p_base;
 361         Set8bppPalette( p_filter, p_filter->p_sys->p_rgb8 );
 362         break;
 363
 364     case VLC_CODEC_RGB15:
 365     case VLC_CODEC_RGB16:
 366         p_filter->p_sys->p_rgb16 = (uint16_t *)p_filter->p_sys->p_base;
 367         for( i_index = 0; i_index < RED_MARGIN; i_index++ )
 368         {
 369             p_filter->p_sys->p_rgb16[RED_OFFSET - RED_MARGIN + i_index] = RGB2PIXEL( p_filter, pi_gamma[0], 0, 0 );
 370             p_filter->p_sys->p_rgb16[RED_OFFSET + 256 + i_index] =        RGB2PIXEL( p_filter, pi_gamma[255], 0, 0 );
 371         }
 372         for( i_index = 0; i_index < GREEN_MARGIN; i_index++ )
 373         {
 374             p_filter->p_sys->p_rgb16[GREEN_OFFSET - GREEN_MARGIN + i_index] = RGB2PIXEL( p_filter, 0, pi_gamma[0], 0 );
 375             p_filter->p_sys->p_rgb16[GREEN_OFFSET + 256 + i_index] =          RGB2PIXEL( p_filter, 0, pi_gamma[255], 0 );
 376         }
 377         for( i_index = 0; i_index < BLUE_MARGIN; i_index++ )
 378         {
 379             p_filter->p_sys->p_rgb16[BLUE_OFFSET - BLUE_MARGIN + i_index] = RGB2PIXEL( p_filter, 0, 0, pi_gamma[0] );
 380             p_filter->p_sys->p_rgb16[BLUE_OFFSET + BLUE_MARGIN + i_index] = RGB2PIXEL( p_filter, 0, 0, pi_gamma[255] );
 381         }
 382         for( i_index = 0; i_index < 256; i_index++ )
 383         {
 384             p_filter->p_sys->p_rgb16[RED_OFFSET + i_index] =   RGB2PIXEL( p_filter, pi_gamma[ i_index ], 0, 0 );
 385             p_filter->p_sys->p_rgb16[GREEN_OFFSET + i_index] = RGB2PIXEL( p_filter, 0, pi_gamma[ i_index ], 0 );
 386             p_filter->p_sys->p_rgb16[BLUE_OFFSET + i_index] =  RGB2PIXEL( p_filter, 0, 0, pi_gamma[ i_index ] );
 387         }
 388         break;
 389
 390     case VLC_CODEC_RGB24:
 391     case VLC_CODEC_RGB32:
 392         p_filter->p_sys->p_rgb32 = (uint32_t *)p_filter->p_sys->p_base;
 393         for( i_index = 0; i_index < RED_MARGIN; i_index++ )
 394         {
 395             p_filter->p_sys->p_rgb32[RED_OFFSET - RED_MARGIN + i_index] = RGB2PIXEL( p_filter, pi_gamma[0], 0, 0 );
 396             p_filter->p_sys->p_rgb32[RED_OFFSET + 256 + i_index] =        RGB2PIXEL( p_filter, pi_gamma[255], 0, 0 );
 397         }
 398         for( i_index = 0; i_index < GREEN_MARGIN; i_index++ )
 399         {
 400             p_filter->p_sys->p_rgb32[GREEN_OFFSET - GREEN_MARGIN + i_index] = RGB2PIXEL( p_filter, 0, pi_gamma[0], 0 );
 401             p_filter->p_sys->p_rgb32[GREEN_OFFSET + 256 + i_index] =          RGB2PIXEL( p_filter, 0, pi_gamma[255], 0 );
 402         }
 403         for( i_index = 0; i_index < BLUE_MARGIN; i_index++ )
 404         {
 405             p_filter->p_sys->p_rgb32[BLUE_OFFSET - BLUE_MARGIN + i_index] = RGB2PIXEL( p_filter, 0, 0, pi_gamma[0] );
 406             p_filter->p_sys->p_rgb32[BLUE_OFFSET + BLUE_MARGIN + i_index] = RGB2PIXEL( p_filter, 0, 0, pi_gamma[255] );
 407         }
 408         for( i_index = 0; i_index < 256; i_index++ )
 409         {
 410             p_filter->p_sys->p_rgb32[RED_OFFSET + i_index] =   RGB2PIXEL( p_filter, pi_gamma[ i_index ], 0, 0 );
 411             p_filter->p_sys->p_rgb32[GREEN_OFFSET + i_index] = RGB2PIXEL( p_filter, 0, pi_gamma[ i_index ], 0 );
 412             p_filter->p_sys->p_rgb32[BLUE_OFFSET + i_index] =  RGB2PIXEL( p_filter, 0, 0, pi_gamma[ i_index ] );
 413         }
 414         break;
 415     }
 416 }
 417
 418 static void Set8bppPalette( filter_t *p_filter, uint8_t *p_rgb8 )
 419 {
 420     #define CLIP( x ) ( ((x < 0) ? 0 : (x > 255) ? 255 : x) << 8 )
 421
 422     int y,u,v;
 423     int r,g,b;
 424     int i = 0, j = 0;
 425     uint16_t *p_cmap_r = p_filter->p_sys->p_rgb_r;
 426     uint16_t *p_cmap_g = p_filter->p_sys->p_rgb_g;
 427     uint16_t *p_cmap_b = p_filter->p_sys->p_rgb_b;
 428
 429     unsigned char p_lookup[PALETTE_TABLE_SIZE];
 430
 431     /* This loop calculates the intersection of an YUV box and the RGB cube. */
 432     for ( y = 0; y <= 256; y += 16, i += 128 - 81 )
 433     {
 434         for ( u = 0; u <= 256; u += 32 )
 435         {
 436             for ( v = 0; v <= 256; v += 32 )
 437             {
 438                 r = y + ( (V_RED_COEF*(v-128)) >> SHIFT );
 439                 g = y + ( (U_GREEN_COEF*(u-128)
 440                          + V_GREEN_COEF*(v-128)) >> SHIFT );
 441                 b = y + ( (U_BLUE_COEF*(u-128)) >> SHIFT );
 442
 443                 if( r >= 0x00 && g >= 0x00 && b >= 0x00
 444                         && r <= 0xff && g <= 0xff && b <= 0xff )
 445                 {
 446                     /* This one should never happen unless someone
 447                      * fscked up my code */
 448                     if( j == 256 )
 449                     {
 450                         msg_Err( p_filter, "no colors left in palette" );
 451                         break;
 452                     }
 453
 454                     /* Clip the colors */
 455                     p_cmap_r[ j ] = CLIP( r );
 456                     p_cmap_g[ j ] = CLIP( g );
 457                     p_cmap_b[ j ] = CLIP( b );
 458
 459 #if 0
 460             printf("+++Alloc RGB cmap %d (%d, %d, %d)\n", j,
 461                p_cmap_r[ j ] >>8, p_cmap_g[ j ] >>8,
 462                p_cmap_b[ j ] >>8);
 463 #endif
 464
 465                     /* Allocate color */
 466                     p_lookup[ i ] = 1;
 467                     p_rgb8[ i++ ] = j;
 468                     j++;
 469                 }
 470                 else
 471                 {
 472                     p_lookup[ i ] = 0;
 473                     p_rgb8[ i++ ] = 0;
 474                 }
 475             }
 476         }
 477     }
 478
 479     /* The colors have been allocated, we can set the palette */
 480     /* FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME FIXME
 481     p_filter->fmt_out.video.pf_setpalette( p_filter, p_cmap_r, p_cmap_g, p_cmap_b );*/
 482
 483 #if 0
 484     /* There will eventually be a way to know which colors
 485      * couldn't be allocated and try to find a replacement */
 486     p_vout->i_white_pixel = 0xff;
 487     p_vout->i_black_pixel = 0x00;
 488     p_vout->i_gray_pixel = 0x44;
 489     p_vout->i_blue_pixel = 0x3b;
 490 #endif
 491
 492     /* This loop allocates colors that got outside the RGB cube */
 493     for ( i = 0, y = 0; y <= 256; y += 16, i += 128 - 81 )
 494     {
 495         for ( u = 0; u <= 256; u += 32 )
 496         {
 497             for ( v = 0; v <= 256; v += 32, i++ )
 498             {
 499                 int u2, v2, dist, mindist = 100000000;
 500
 501                 if( p_lookup[ i ] || y == 0 )
 502                 {
 503                     continue;
 504                 }
 505
 506                 /* Heavy. yeah. */
 507                 for( u2 = 0; u2 <= 256; u2 += 32 )
 508                 {
 509                     for( v2 = 0; v2 <= 256; v2 += 32 )
 510                     {
 511                         j = ((y>>4)<<7) + (u2>>5)*9 + (v2>>5);
 512                         dist = (u-u2)*(u-u2) + (v-v2)*(v-v2);
 513
 514                         /* Find the nearest color */
 515                         if( p_lookup[ j ] && dist < mindist )
 516                         {
 517                             p_rgb8[ i ] = p_rgb8[ j ];
 518                             mindist = dist;
 519                         }
 520
 521                         j -= 128;
 522
 523                         /* Find the nearest color */
 524                         if( p_lookup[ j ] && dist + 128 < mindist )
 525                         {
 526                             p_rgb8[ i ] = p_rgb8[ j ];
 527                             mindist = dist + 128;
 528                         }
 529                     }
 530                 }
 531             }
 532         }
 533     }
 534 }
 535
 536 #endif
 537