[Openicc] L* was: MS on HDR CMS :)

[Jan-Peter Homann]

Hello Chris, hello list
For a good quality in displaying RGB on a monitor, the RGB workingspace 
should have the same gamma / gradation as the monitor calibration.
If we look at the standard gamma 1,8 and 2,2 we by converting equal RGB 
values to Lab, we see that the very dark RGB colors for Gamma 2,2 don´t 
produce differences and for Gamma 1,8 we have it in the very light colors.

In Germany several photostudios, photo post production specialists and 
prepress shops are using eciRGBv2 on monitors calibrated to L*.
They are very satisfied with the results.

Regards
Jan-Peter

Chris Murphy wrote:
> On Feb 11, 2008, at 1:43 PM, Kai-Uwe Behrmann wrote:
>   
>> You emphasise printing only. But I'd think we see consuming of much  
>> more
>> media in form of movie, TV and so on or at least thise media are  
>> growing
>> compared to print. Print is no longer the only graphic output media.
>>     
>
> I actually did not address this part previously, and being crazy I  
> realize this three days after the fact.
>
> The emphasis on print is not mine, but the ECI web site:
>
> "The focus of the eciRGB_v2 profile still is on the print and  
> publishing industry"
>
> That's predominately an 8bpc workflow, and a TRC that's closer to  
> gamma 1.8 function than L*. So I don't see the compatibility or  
> usefulness of L* here.
>
> The web site goes on to say it's recommend when converting from Raw  
> data to 16bpc image data. Well if we have that many bits, it doesn't  
> seem the TRC selection matters. The source data has no encoding, it  
> may be linear, or close to it, and so when tone mapping all the way  
> over to L* we have some loss. And then we have loss again as we tone  
> map back to a TRC closer to print (or even display, movie or video).  
> In practice the loss is greater for Raw because we first convert to  
> gamma 1.8 or 2.2 space, then the workflow calls for conversion to L*,  
> then back to some other TRC. It's a lot of conversions. If we were  
> talking about medical imaging, with DICOM images and displays, then  
> OK this is more compelling.
>
> As you say other media are growing, but that's not mentioned for this  
> color space. And the direction for most media is not improvement of  
> 8bpc workflows, but rather improvement for 16bpc and even higher bit- 
> depth workflows where encoding is really pointless.
>
> So I'm all ears if someone has a compelling explanation about L* and  
> ECI-RGBv2.0.
>
> Chris Murphy
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>
>   


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