Replacing specific color range

no-reply@allegro.cc (GullRaDriel) — Fri, 20 Apr 2007 01:06:47 +0000

Take a look at the picture, all colors except hands are 'pure' colors.

{"name":"591971","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/b\/8\/b8d1678789bd504182193c7391f1b202.png","w":320,"h":240,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/b\/8\/b8d1678789bd504182193c7391f1b202"}

I need to replace each of these color by another one, but quickly.

What is the way , faster than getpixel, that I can use ?

Thanks

no-reply@allegro.cc (Johan Peitz) — Fri, 20 Apr 2007 01:21:18 +0000

If you're using 8bit I would go for palette changes, but something tells me you are not...

no-reply@allegro.cc (Johan Halmén) — Fri, 20 Apr 2007 01:24:08 +0000

Use palettes. Or prerender, either using a graphic editor (great opportunity to discuss in this thread why Gimp sucks/is great) or during game setup.

no-reply@allegro.cc (CGamesPlay) — Fri, 20 Apr 2007 02:32:29 +0000

Use palettes, prerender, or use OpenGL.

[append]
Next person to post has to add something to the list!

no-reply@allegro.cc (Onewing) — Fri, 20 Apr 2007 02:42:09 +0000

Quote:

Use palettes, prerender, or use OpenGL.

Or use getpixel to build an array and then use the array to putpixel back the colors with a given offset to change your colors, as long as your image doesn't...change.

no-reply@allegro.cc (ImLeftFooted) — Fri, 20 Apr 2007 02:46:52 +0000

There are gradients there... Ya good luck. Easier to redo the art.

no-reply@allegro.cc (Matt Weir) — Fri, 20 Apr 2007 03:16:01 +0000

Gradients can be overcome by converting to HSL and not using the lightness but there will be problems if any of the gradients fades to pure black. The human brain is pretty good at putting imaginary boundries in images.

As far as I can think, getpixel is the only way and it will be slow. I can think of a few ways to optimize but all sacrifice accuracy.

+1 for finding another way.

Matt.

no-reply@allegro.cc (Johan Halmén) — Fri, 20 Apr 2007 12:07:50 +0000

Solder a switch to your monitor cable, which switches the r, g and b channels.
I win!

no-reply@allegro.cc (GullRaDriel) — Fri, 20 Apr 2007 13:24:46 +0000

I made some tests, and it is working (as expected) with getpixel/putpixel.

I will perhaps try to use the "block data transfer" method.

Here is the result, the colors are random and take the gradient :
[img http://www.allegro.cc/files/attachment/591972]

And here is the code :

#SelectExpand
   1#include 
   2
   3BITMAP *in , *out , *buf;
   4
   5int x , y,  it , c , cc, r, g , b , r1 , b1 , g1 , c1 , c2 , c3 , c4 , c5 ,c6,c7 ;
   6
   7int main( int argc , char *argv[] ){
   8
   9allegro_init();
  10install_keyboard();
  11install_mouse();
  12
  13
  14set_color_depth( 32 );
  15
  16set_gfx_mode( GFX_DIRECTX_WIN , 320 , 240 , 0 , 0 );
  17
  18in = load_bitmap( "test.bmp" , NULL );
  19
  20out = create_bitmap( in -> w , in -> h );
  21
  22buf = create_bitmap( SCREEN_W , SCREEN_H );
  23clear( buf );
  24clear( out );

c1 = makecol( rand()%255 , rand()%255 , rand()%255 );
c2 = makecol( rand()%255 , rand()%255 , rand()%255 );
c3 = makecol( rand()%255 , rand()%255 , rand()%255 );
c4 = makecol( rand()%255 , rand()%255 , rand()%255 );
c5 = makecol( rand()%255 , rand()%255 , rand()%255 );
c6 = makecol( rand()%255 , rand()%255 , rand()%255 );
c7 = makecol( rand()%255 , rand()%255 , rand()%255 );

for( x = 0 ; x < in -> w ; x ++ )
{
  for( y = 0 ; y < in -> h ; y ++ )
  {
    cc = -1;
    
    c = getpixel( in , x , y );
    r = getr( c );
    g = getg( c );
    b = getb( c );
    
    if( r > 88 && b == 0 && g == 0 ) /* rouge tete */
       cc = c1 ;
    if( r > 88 && b > 0 && g == 0 )  /* roste cou */
       cc = c2 ;
    if( r == 0 && b > 0 && g > 0 ) /* bleu manche */
       cc = c3 ;
    if( r > 88 && g > 0 && b == 0) /* veste */
       cc = c4 ;
    if( b > 0 && r == 0 && g == 0 ) /*pantalon*/
       cc = c5 ;
    if( r > 88 && b > 0 && g > 0 ) /*mains*/
       cc = c6 ;
    if( r > 0 && r <= 88 && b == 0 && g == 0 )
      cc = c7;
    if( cc != -1 )
    {
    
    r1 = getr( cc );
    g1 = getg( cc );
    b1 = getb( cc );
    
       
    if( r > 0 )
    {
      it = r;
    }
    
    if( g > 0 )
    {
      it = g ;
    }
    
    if( b > 0 )
    {
        it = b ;
    }
    
    r1 = (r1 * it)/255 ;
    g1 = (g1 * it)/255 ;
    b1 = (b1 * it)/255 ;
    
    if( r1 < 0 ) r1 = 0;
    if( g1 < 0 ) g1 = 0;
    if( b1 < 0 ) b1 = 0;
    if( r1 > 255 ) r1 = 255;
    if( g1 > 255 ) g1 = 255;
    if( b1 > 255 ) b1 = 255;
    
    putpixel( out , x , y , makecol( r1 , g1 , b1 ) );
    }
  }
}
  97do{
  98
  99if( key[KEY_SPACE] )
 100{
clear( out );

c1 = makecol( rand()%255 , rand()%255 , rand()%255 );
c2 = makecol( rand()%255 , rand()%255 , rand()%255 );
c3 = makecol( rand()%255 , rand()%255 , rand()%255 );
c4 = makecol( rand()%255 , rand()%255 , rand()%255 );
c5 = makecol( rand()%255 , rand()%255 , rand()%255 );
c6 = makecol( rand()%255 , rand()%255 , rand()%255 );
c7 = makecol( rand()%255 , rand()%255 , rand()%255 );

for( x = 0 ; x < in -> w ; x ++ )
{
  for( y = 0 ; y < in -> h ; y ++ )
  {
    cc = -1;
    
    c = getpixel( in , x , y );
    r = getr( c );
    g = getg( c );
    b = getb( c );
    
    if( r > 88 && b == 0 && g == 0 ) /* rouge tete */
       cc = c1 ;
    if( r > 88 && b > 0 && g == 0 )  /* roste cou */
       cc = c2 ;
    if( r == 0 && b > 0 && g > 0 ) /* bleu manche */
       cc = c3 ;
    if( r > 88 && g > 0 && b == 0) /* veste */
       cc = c4 ;
    if( b > 0 && r == 0 && g == 0 ) /*pantalon*/
       cc = c5 ;
    if( r > 88 && b > 0 && g > 0 ) /*mains*/
       cc = c6 ;
    if( r > 0 && r <= 88 && b == 0 && g == 0 )
      cc = c7;
    if( cc != -1 )
    {
    
    r1 = getr( cc );
    g1 = getg( cc );
    b1 = getb( cc );
    
       
    if( r > 0 )
    {
      it = r;
    }
    
    if( g > 0 )
    {
      it = g ;
    }
    
    if( b > 0 )
    {
        it = b ;
    }
    
    r1 = (r1 * it)/255 ;
    g1 = (g1 * it)/255 ;
    b1 = (b1 * it)/255 ;
    
    if( r1 < 0 ) r1 = 0;
    if( g1 < 0 ) g1 = 0;
    if( b1 < 0 ) b1 = 0;
    if( r1 > 255 ) r1 = 255;
    if( g1 > 255 ) g1 = 255;
    if( b1 > 255 ) b1 = 255;
    
    putpixel( out , x , y , makecol( r1 , g1 , b1 ) );
    }
  }
}
 174}
 175
 176stretch_blit( out , buf , 0 , 0 , out -> w , out -> h , 0 , 0 , buf -> w , buf -> h );
 177
 178blit( buf , screen , 0 , 0 , 0 , 0 , buf->w , buf->h );
 179
 180}while( !key[KEY_ESC ] );
 181
 182allegro_exit();
 183
 184}END_OF_MAIN()

no-reply@allegro.cc (miran) — Fri, 20 Apr 2007 16:33:47 +0000

I only skimmed over the code but I didn't see any rgb2hsv and vice versa conversions so I'm guessing you're not doing it right. What you want to do is this:

For each pixel:

1. Read colour (RGB format)
2. Convert to HSV
3. Rotate H by a certain number of degrees.
4. Convert back to RGB.
5. Write colour back to image.

no-reply@allegro.cc (GullRaDriel) — Fri, 20 Apr 2007 17:32:46 +0000

Thanks for your help, but there is no need for me to use any other conversion than makecol and getX :-)

The color value of the input picture is here for two reason: having the form to fill with a color, and picking the value as a percentage from 0 to 255.

The whole thing is working as expected, it just need some king of optimisation as it will cause some load time.

Here is the new version, where default replacement color is on screen for us to verify that it is using it correctly.

Before:

After:
{"name":"591975","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/c\/e\/cefcd7e9c42f3ac91cf96ab1e48b02b6.jpg","w":806,"h":625,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/c\/e\/cefcd7e9c42f3ac91cf96ab1e48b02b6"}

Executable + source (Win32) ( 7z archive )

I am waiting for give the cookies. Please post me the answer ;-) huhuhu

no-reply@allegro.cc (Indeterminatus) — Fri, 20 Apr 2007 17:50:50 +0000

As requested, a post so you can hand out cookies.

no-reply@allegro.cc (GullRaDriel) — Fri, 20 Apr 2007 17:57:04 +0000

;-p

no-reply@allegro.cc (Matt Weir) — Sat, 21 Apr 2007 05:21:28 +0000

Your pictures look like they contain a large ammount of dead space. If your checking every pixel in the large space perhaps you could divide and conquer. Only check every nth pixel (in both dimensions) if the nth pixel is one that needs to be changed then go back n/2 and check that pixel (and so on). You value for n would have to be one where you won't missed anything important so if your working on a picture with skinny lines it won't help but even at n=2 you'll save a lot of time. Basically trading precision for speed.

Matt.

no-reply@allegro.cc (Andrei Ellman) — Sun, 22 Apr 2007 23:24:14 +0000

Quote:

What is the way , faster than getpixel, that I can use ?

_getpixel
If the colour-depth is known, you might want to use getr8, getr16, getr24, getr32 etc. instead of getr.

Quote:

r1 = (r1 * it)/255 ;

If you don't mind the result being in the range 0-254 instead of 0-255, you can divide by using a shift. The code would then become.r1 = (r1 * it)>>8;. While not as accurate as the /255 method, it will be a lot faster.

Also, you might want to consider using 8-bit graphics and using colour-map tables and draw_lit_sprite().

AE.

no-reply@allegro.cc (GullRaDriel) — Mon, 23 Apr 2007 00:15:37 +0000

Matt Weir: This is only a test picture extracted from an animation, the picture when in it final form is 'clipped' to the nearest non-masked pixel. Anyway thanks for the tip !

Andrei: I will try the _getpixel way. Also: the >>8 seems good too.

no-reply@allegro.cc (James Stanley) — Fri, 27 Apr 2007 17:34:58 +0000

GIMP rules.

no-reply@allegro.cc (GullRaDriel) — Sat, 28 Apr 2007 02:14:16 +0000

Yeah perhaps. But GIMP does not do real time painting in my code.