Re: Multiple profile device support

[Pascal de Bruijn <pmjdebruijn pcode nl>]

On Wed, May 26, 2010 at 6:02 PM, Richard Hughes <hughsient gmail com> wrote:
> On 26 May 2010 16:50, Pascal de Bruijn <pmjdebruijn pcode nl> wrote:
>> Does this actually make sense? Not really....
>
> There are wide-gamut monitors that allow different "modes" so you
> artificially lower the gamut range so you don't blow your eyes when
> you try to view uncorrected content. It turns out HP have a large
> number of those monitors "in the field" so to speak, and they are
> quite keen on getting them to work correctly.

I actually have a HP screen, it does have an sRGB mode indeed... But
this means the screen fiddles with it's internal LUT a bit to fake
this... It's not really a great idea...

The extra saturation because of the wide gamut usually is not that
much of a problem... It's usually the high brightness combined with
the extra saturation that is the problem... High brightness is usually
frowned upon in color management anyways.

When I turn up my brightness to 100% I need sunscreen to sit behind my
screen for prolonged periods...

That's why I set my brightness to a value that correlates to ~200cm/m2.

>> A single profile well-made against daylight or a strobe can usually
>> cover 80/90% of your usage scenario's, unless you're really anal
>> retentive...
>
> Sure, but people that care about color management and anally retentive
> people are very co-morbid :-)

Hard to argue with that.

>>> * Scanners, where nothing can be altered
>>
>> Think of negative/positive scanning as well, which could mean a
>> profile per type of negative.
>
> Right, makes sense.
>
>> This makes very little sense! At least if I'm getting this right (big IF) :)
>>
>> When developing RAWs:
>> Which profile to apply is a decision you make on-the-fly when working
>> with a RAW converter...
>
> Yes, that's how it used to be. The RAW converter has to be "set"
> manually with the ICC profile to use, which is gobbledygook that
> nobody will do. That's something I want to automate, see
> http://blogs.gnome.org/hughsie/2010/05/23/gnome-color-manager-and-you/
> for details.

And that's how it should be in the future... GCM can only help by not
providing any irrelevant profiles...

So if I have a 400D, it could provide 400D profiles only so if I have
a 5D as well, I won't see those profiles...

But GCM cannot tell whether a picture needs the "daylight" profile or
the "studio" profile...

Obviously this is where the default comes in... But the user still
needs to be easy-able to make a last minute decision about this,
without having to start gcm-prefs.

> The idea is that the RAW converter (darktable, f-spot, whatever) calls
> into GCM to find out the ICC profile that should be used for each
> file.
>
>> When printing:
>> Which profile to apply is a decision you make on-the-fly when loading
>> the printer with paper before printing... This could very well be per
>> 1 sheet...
>
> Sure. The CUPS parts are very much still up in the air and are being
> worked on. We don't have a very good story there yet.

Boatload of work... :(

>> When scanning:
>> To set a generic scanner profile this make sense... but for
>> negatives/transparancies this is something you would apply on-the-fly
>> using the scanning tool...
>
> Right, but presumably one wants to be used by default? For something
> like simple scan we can just tell it the default profile and there is
> no UI to configure.

Again the scanning app doesn't know whether I'm scanning a
transparancy or not...

For an application like simple-scan this could be omitted because it's
_not_ intended as a scanner's swiss-army-knife...

But for say XSane (if anybody is still working on that, god forbid),
it would still be the end-user that need to select which exact profile
he needs to apply to his image... Obviously profiles for completely
different scanner types could be omitted.

>
>> So I'm not sure to what extent it is useful for GCM to get involved
>> here... Except for setting the default profile :)
>
> I'm really pushing GCM into the CMM role, where the defaults are got
> from GCM rather than set in each and every application.

That's good... Centralised defaults are VERY good :)

Though there is another thing you need to keep track of...

Profiles are not per-se interchangeable between different
applications... For example UFRaw does not output 100% true linear RGB
RAW before applying the profile... DCRAW/Darktable do at least as far
as I know...

Regards,
Pascal de Bruijn