hello,

in general, factor is a value that you mutiply by, determining how strong the influence of something is (here of A).

If you choose factor to be 1.0
A would be as strong as B (100%)

If you choose factor to be 0.2
A would be far less strong than B (20%)

If you choose factor to be 0.0
B would always win.

If you choose factor to be 1.4
A would win more often.

Think of factor as being the influence of A compared to B in the resultiung im image.

Greetings, Chrisir      

i've seen on web that the factor specified is based on the alpha component of the source pixel, wich is represented by the first 8 bits ( from the left ) of the 32-bit integer representing the pixel color. These leftmost bits are also referred to as the highest bits.

Source : http://books.google.fr/books?id=TKgfVpWPb0sC&pg=PA463&lpg=PA463&dq=C+=+max(A*factor,+B)+processing&source=bl&ots=pNHzVwA2kI&sig=gtyovWBGUXFRAmaqRPQ5VfeYHr8&hl=fr&sa=X&ei=sDqJUIKUHeOq0QWy9YHYBA&ved=0CCsQ6AEwAQ#v=onepage&q=C = max(A*factor, B) processing&f=false

page 464

What should i think of it ?

Actually im trying to build a Light Painting Real time system.

I got it.

But im trying to build it into low level code to build it on open framework..

And that blend thing is really annoying for me.. :(

Reagarding what they say on that book.

My code is :

1. for (int y = 0; y < capWidth * capHeight; y++) {
2.     int factor = (pixels[y]>>24) & 0xff;
3.    
4.     pixels[y]= max(pixels[y]*factor,previousFrame.pixels[y]);
5.   
6.  
7.   }