[Gllug] FLOSS

[abower at thebowery.co.uk]

On Wed, Nov 05, 2003 at 01:02:15PM +0100, John Hearns wrote:
> On Wed, 5 Nov 2003, Tethys wrote:
> 
> > Interesting. I'd been wondering what had happened to Hollywood/Film Gimp.
> > Looks like this is the answer... In the process, they've gone from Film
> > Gimp's 16 bits per channel up to a staggering 32 bits (128 bits per pixel
> > for full RGBA). I can't off the top of my head think of a use for that
> > depth of colour, even to prevent rounding errors. It'll help when treating
> > greyscale images as RGB, but little else. I mean, it gives around 2 x 10^22
> > times more colour data than the human eye can process. That's quite a bit...

It is to do with the weird ways of the dynamic range of film, don't ask me ask
a colour scientist. I once got trapped in the corner of the bar by one and he
boggled my mind entirely.... I also think it has something to do with being to
uprate the film if part of your stock comes out too dark or something as then
you have a greater colour range to manipulate against as even though you can't 
see the differences in the dark shadows a computer can, and when it is decided 
that you need to brighten this darkness it will improve the clarity and 
definition as you will have more data to play with. 

I guess the way to simulate this would be to get a 24 bit colour image and then
create an 8 bit (i supposed you could try 16bit but you will be able to push
that quite a bit further) colour image from it and then play around with 
raising and dropping the brightness and contrast... you will soon find that 
you won't be able to change the levels as far on the 256 colour image compared 
to the 24 bit image without losing detail.

I recall working on one film which was "too green" so they played around with
the colour space to reduce the green component which is where having the 32bits
of colour helped.  

Adam
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