Re: [Gimp-developer] Soft proofing and the GIMP Display Filters and Color Management settings

On 03/10/2014 04:06 PM, Liam R E Quin wrote:
On Mon, 2014-03-10 at 08:55 -0400, Elle Stone wrote:

The odd behavior of the display filters came to my attention because
I've been working on rewriting some of the GIMP color management
documentation and so took a closer look at what all the display filters do.

Documenting (briefly) the wrongness might help demonstrate what needs to
be done, too.

In the original post, e - i and especially e, f, g describe odd and wrong results:

On 03/02/2014 12:51 PM, Elle Stone wrote:
e. If the "Mode of operation" is set to "Print simulation" in the
globally applied "Edit/Preferences/Color Management" settings dialog,
and if the user also chooses to activate the per image "Color Proof"
display filter, then the global choices made in the Color Management
settings are applied on top of the per image choices made in the
Color Proof Display filter, and the results are wrong.

f. Multiple active copies of the Color Proof Display Filter in turn
apply each copy's soft proofing choices, with increasingly wrong results.

g. One active copy of the Color Management display filter acts as
expected. But multiple active copies of the Color Management display
filter each in turn apply the conversion from the image ICC profile
to the monitor ICC profile.  . . .
when using an actual monitor profile (sRGB doesn't adequately
describe LCD monitors), successively applying multiple copies of the
Color Management filter results in increasingly noticeable and wrong
color and tonality changes.

e is just wrong behavior.

f and g could be considered the result of users not thinking about what they are doing. But the display filter gui shouldn't allow dragging multiple copies of the Color Management or Soft Proofing display filters over to the active pane as doing so makes no sense at all.

I agree 100% that soft proofing requires the ability to quickly switch
gamut checks on and off, and also quickly enable/disable soft proofing.
+1 although for print work at this point you have to move to Krita or
Photoshop, most likely photoShop with a "preflight" plugin, so that you
can adjust individual plates (e.g. with dodge) for the different ink
colours (CMYK at the most basic, or two plates for a duotone).

The decision is (as I understand it) for GIMP to stay out of the print
shop so this all gets a little fuzzy for me.

I don't know anything about CMYK printing and I've never used the CM+ plugin, so please bear with me while I ask a couple of questions:

Putting *editing* CMYK channels to one side, is it useful to modifythe RGB channels while soft proofing to a CMYK profile (or even n-channel profile whether color or black and white)? I thought that was what the CM+ plugin made possible? Is this an example of what Gez calls "late binding"?

But there are plenty of non-print use cases for soft proofing, of
course, including e.g. targeting a specific mobile device (even though
there's huge variation between individuals, there are basic limits on
the colour you can usefully work with) or for projection at a conference
or in an art gallery.

There's also converting from a camera input profile to an RGB working space, and from one RGB working space to another, and from a larger RGB working space to sRGB for display on the web. Also, some commercial printers (for example, some print shops with Chromira and Frontier printers) provide RGB printer profiles to customers to use when soft proofing.

A common way to soft proof requires having the image open twice to
compare the original with the soft proofed version.

Yes. It's unfortunate that Single Window Mode makes this hard.

The current GIMP preferences allow you to choose "Print Simulation" in
"Preferences/Color Management/Mode of operation". But that sets *all*
open images to Print Simulation mode, for which I can't think of any use
No - a display filter makes more sense, agreed. Then you could maybe
make the filter apply be default to all images if you really wanted?
There should be (is??) a way to include something in the title bar
and/or status bar to show which display filters are active.

Having the title/status bar(s) show which display filters are active would be very useful, especially given that if you close the display filter window, any activated filters (or deactivated, in the case of the Color Management filter) are still applied to the image.


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]