New article on color management

Started Apr 26, 2013 | Discussions thread
OP gollywop Veteran Member • Posts: 8,284
Re: Yeah...

Hugowolf wrote:

gollywop wrote:

Hugowolf wrote:

gollywop wrote:

And, although the spaces are based on integer values, processing is done with floating point numbers.

In processors like RPP, Rawtheraee, and PhotoNinja, yes.  In ACR/PS, I don't think so.  Adobe still uses integer arithmetic as far as I know.  But I'd certainly be willing to be guided to documentation that says otherwise.

I would be surprised if it were otherwise. It is standard practice to map 0-255 to 0-1, it is just much easier to algorithmically process that way.

Surprise is indeed fun. But I'm waiting for documentation that supports the surprise.

Meanwhile normalizations do not require floating point.

It just may well be the way I have always dealt with it. But I am pretty sure I have heard of others doing it this way, perhaps from Eric Chan.

For me it has to do with closure. Integers are not closed under division.

Closure has nothing to do with it.  Floating-point numbers are not closed under division either (unless of infinite precision -- both mantissa and exponent).  I'm sure they are using normalizations, particularly for things like blends, but they're likely carrying out the operations using fixed-point arithmetic, not floating point.

If I have time, I will look for sources.


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