[SDL] How to gray out a button image?

Wed Apr 16 01:59:29 PDT 2008

Andreas Schiffler skrev:
>
> You may want to use integer math ...
> http://en.wikipedia.org/wiki/YUV#Numerical_approximations
>
Thanks for the link. It gives the floating point values with 3 digits (I 
just got 2 before). I implemented a fixed point calculation. Then I 
googled for the magic numbers that I used and found this program that 
does exactly the calculation that I am doing (search for lumtbl): 
http://fisheye1.cenqua.com/browse/~raw,r=11.44/brlcad/brlcad/libfb/if_X24.c