New article on color management

Started Apr 26, 2013 | Discussions thread
gollywop
Veteran MemberPosts: 5,681
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Re: Yeah...
In reply to Hugowolf, Apr 29, 2013

Hugowolf wrote:

gollywop wrote:

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 (unless of infinite precision -- both mantissa and exponent).

No, but the errors involved are less spectacular than those of truncation.

And that is supposed to prove . . . ?

What you might think about, however, is how PS manages to have almost instant response with it's sliders, whereas the raw processors that we know use floating-point (RPP, Rawtherapee, PhotoNinja, to name a few) all require a significant processing lag after making an adjustment.

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gollywop

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