Hey, I'm loving the new PImage blending modes!  I don't know how you got the equations and explanations for the Photoshop modes.. I looked for a long time trying to find those once..

I had an idea to add.  How about a blending mode that simply 'keys out' pure black?  So you can do sprites without having to create alpha masks.  

[Also the "color" blending mode in Photoshop is one of my favorites...But that's another suggestion altogether..]

>why not just read your image and for every black pixel set
>its alpha channel to transparent.. thats how i would do it

OK fine, I guess you don't need to cater to my laziness..

Thx for the blending mode equations!

here's a example of how to do it:

it reads an image and searches for white pixels.. it there it one, it will just write a new color with alphachannel equal to 0, which would make it transparent..
hope it helps.


PImage img;
PImage imga;


void setup()
{
 img = loadImage( "grid.png" );
 imga = createImage( img.width, img.height, RGB );
 
 
 for( int j=0; j<img.height; j++ )
 {
   for( int i=0; i<img.width; i++ )
   {
       // index to each pixel in the image
       int pix = i + j * img.width;

       // if this pixel color white ?
       if( color(img.pixels[pix]) == color(255) )
       {
         // if yes, change alpha channel
         imga.pixels[pix] = color(255, 255, 255, 0);
       }
       else
         // if not just copy pixel from the image
         imga.pixels[pix] = img.pixels[pix];
   }
 }  
}


void draw()
{
 background( 0, 255, 0 );
 image( imga, 0, 0 );
}