[argyllcms] Re: Photoshop CS4/CS5 believes colprof XYZ LUT profiles are 'defective'
- From: Alexander <adfirestone@xxxxxxxxx>
- To: argyllcms <argyllcms@xxxxxxxxxxxxx>
- Date: Wed, 19 Jan 2011 16:17:48 -0800
Graeme Gill wrote:
> Alexander wrote:
>
>> "The monitor profile * appears to be defective." When I say use anyway, it
>> seems to be
>> OK, but something must be a bit off if Photoshop is balking at it.
>>
>
> OK, the response from Adobe is:
>
> ACE contains some monitor profile validation code to attempt to filter out
>> bad profiles.
>> One test it performs is to convert Lab white (100,0,0) -> RGB to check
>> that it’s at
>> least (f7,f7,f7). It also converts RGB (ff,ff,ff) -> Lab to test that it’s
>> reasonably
>> close to white.
>>
>> With this particular profile, GDM-F520_2011-01-14.icm, ACE got RGB
>> (f1,f6,ef), which
>> caused it to report that it was a “bad” monitor profile to Photoshop.
>>
>
> So it is a result of a not very accurate B2A white point mapping. This is
> likely
> a result of the D50 white not falling exactly on a grid point, given that
> D50 XYZ is 0.9642, 1.0000, 0.8249, while the PCS range is to 1.999969, so
> that unlike Lab PCS, the white point falls somewhere in the middle...
>
> I'll see if I can do something about this for the next release.
>
> Graeme Gill.
>
>
So if I'm understanding correctly, use of this profile would result in a
reduced luminance white point and increased banding from clipped values
(~94% vs >=97% usable)?
Any manual tweaking I can do in the meantime with my ti3 measurements or
colprof in order to forcibly generate a XYZ profile ACE finds acceptable?
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