Re: [ft-devel] gamma correction demo images

[Nikolaus Waxweiler]

Interesting paper, although I know too little about the science behind 
it to comment on how valid these results are on a wide range of screens. 
The paper itself states that numbers may vary significantly between 
displays and viewing conditions.

Here's a comparison of the paper's filter to FT's light filter: 
http://postimg.org/image/mxc6oa6mv/full/ (no stem darkening). The 
paper's filter appears slightly sharper or more contrasty on my monitor 
but also slightly more colorful than FT's light filter.

Werner, Dave, what's your opinion on this? I would like to change the 
documentation of ftlcdfil.h to note that stem darkening is better than 
filters going over 0x100 and update the filter recommendation to the 
light filter for now. Also, where does the [a-c, a+c, 2a, a+c, a-c] 
formula come from? Is the "[a b c b a] where 2a+2b+c=1" formula newer? I 
could include the paper's filter in the documentation and sprinkle it 
with some source citations.

[1]: [a, b, c, b, a] where a = 0.0, b = 0.3, c = 1 - 2a - 2b = [0, 0.3, 
0.4, 0.3, 0] =~ [0x00, 0x4D, 0x66, 0x4D, 0x00] with slight rounding 
errors ;)