Design issues (opengl, hdr, channels, pigment(?))

[Schleimer, Ben]

Hi,
> Well, graphics cards don't provide the same
> precision that the cpu does, so 
> the results of computations can come out
> differently: 
>
http://www.gpgpu.org/wiki/FAQ#Where_can_I_get_information_about_GPU_floating_point_precision.3F_Is_it_IEEE-compliant.3F.

  The article just points out that the cards do
rounding on floats/doubles differently then IEEE 754.
If you convert your uint8 channels into float, I
seriously doubt you'll have precision problem unless
you're trying to blend thousands of channels (24bits
mantissa - 8bits = 16bits of space before you hit
rounding problems) 

Of course this needs to be tested and obviously, the
above doesnt apply if there are other problems with
GPU floating point.

> 
> And if I ever get down to implementing a fast
> projection mode by putting all 
> layers in u18 rgba textures & blending them using
> opengl, you can bet the 
> results will be different from what we get when we
> carefully blend u16 lab 
> layers on the cpu:-).



 Cheers,
Ben

"He who writes the code gets to choose his license, and nobody else gets to complain" - Linus Torvalds
IMHO, it should read - "He who writes the code gets to choose his license, and everybody else complains."