Преобразовать 256-цветный PCX файл в 16-цветный PCX файл

//---------------------------------------------------------------------------
 
#include "wingraph.h"
#include <time.h>
#pragma hdrstop
 
//---------------------------------------------------------------------------
 
#pragma argsused
 
//---------------------------------------------------------------------------
#pragma pack( push, 1 )
typedef struct head
 {
  unsigned char   ID;
  unsigned char   Version;
  unsigned char   Coding;
  unsigned char   BitPerPixel;
  unsigned short  XMin;
  unsigned short  YMin;
  unsigned short  XMax;
  unsigned short  YMax;
  unsigned short  HRes;
  unsigned short  VRes;
  unsigned char   Palette[48];
  unsigned char   Reserved;
  unsigned char   Planes;
  unsigned short  BytePerLine;
  unsigned short  PaletteInfo;
  unsigned short  HScreenSize;
  unsigned short  VScreenSize;
  unsigned char   Filler[54];
 } TPCXHeader;
#pragma pack( pop )
 
long fsize_(FILE *stream)
{
   long pos_, leng;
   pos_ = ftell(stream);
   fseek(stream, 0L, SEEK_END);
   leng = ftell(stream);
   fseek(stream, pos_, SEEK_SET);
   return leng;
}

//---------------------------------------------------------------------------
#include "PCX.h"
 
//---------------------------------------------------------------------------
void main()
{
  // открываем файл
  FILE *f = fopen("CAT256.pcx", "rb" );
  int size = fsize_( f );
  LPVOID buffer = malloc( size + 1 );
  memset( buffer, 0, size );
  fread( buffer, size, 1, f );
  fclose( f );
  TPCXHeader pcx = { 0 };
  memcpy( &pcx, buffer, sizeof( TPCXHeader ) );
  memcpy(
    &( ( byte* )buffer )[0],
    &( ( byte* )buffer )[sizeof( TPCXHeader )],
    size -= sizeof( TPCXHeader ) );
  realloc( buffer, size);
  int width = pcx.XMax - pcx.XMin + 1;
  int height = pcx.YMax - pcx.YMin + 1;
  CURRENTDEPTH = pcx.BitPerPixel;
  resize( width-1, height+1);
  int count = 0;
  byte *rgb = ( byte* )malloc( 4 );
  memset( rgb, 0, 3 );
  int x = 0;
  int y = 0;
  for( int _set = 0; _set < size - 769; _set++ )
  {
    int X = ( ( byte* )buffer )[_set];
    if ( ( X & 0xC0 ) == 0xC0 )
    {
      count = ( X & 0x3F );
      X = ( ( byte* )buffer )[++_set];
    }
    else
      count = 1;
    memcpy( &rgb[0], &( ( byte* )buffer )[(size - 768 ) + ( X * 3 )], 3 );
    for ( int i = 0; i < count; i++, x++ )
    {
      if ( ( x + ( ( width % 2 == 0 ) ? 1 : 0 ) ) == width )
      {
        x = 0;
        y++;
        break;
      }
      setpalette( X, RGB( rgb[0], rgb[1], rgb[2] ) );
      putpixel(
        x,
        y,
        X );
    }
  }
  free( rgb );
  free( buffer );
}