[Openicc] Questions about color pickers and graphics libraries under LINUX

[Graeme Gill]

Chris Murphy wrote:

> But in an ICC context, things are very output-referred centric. Most  
> of the workflow assumes things are output-referred, i.e. they are  
> rendered to look-good when reproduced on a device with output/print  
> contrast ratio (or dynamic range). The ICC spec defines the contrast  
> ratio for the perceptual reference medium as being 288:1. That's  
> really very high and for most situations the dynamic range of print  
> is actually a lot lower than this.

Yes. There are ways of manipulating ICC profiles to cope better with
this, but it's not obvious, and probably won't be very compatible.
Display and Input profiles have always been rather poorly dealt with
by ICC profiles compared to print.

> So I don't think that encoding alone is not the indicator of what is  
> or isn't HDR. It's about actual dynamic range.

Some of the OpenEXR infra-structure has tackled profiling
such HDR spaces. The approach is to log encode the levels,
and the use a 3D Lut. I'm not sure how well it works, though
I would guess that (as always) it depends on how well
behaved the device is.

Graeme Gill.