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gimp and ICC color working spaces

 
 
Dale
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      11-14-2012
gimp has 2 use cases

1) monitor proofing
2) print proofing

yet it only has RGB and CMYK choices for working spaces

I don't know if Photoshop or other software has a CIE colorimetric
choice for working space, but in order to measure and track color it
would be a lot easier to have one

I know there are issues like gamut differences and rendering intents

but if you want to measure the colorimetry of the monitor or proof and
match it to the print, you need to start with CIE, not RGB or CMYK,
ideally CIECAM but ICC has not gone there yet as far as I know


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Dale
 
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Thomas Richter
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      11-14-2012
Am 14.11.2012 05:56, schrieb Dale:
> gimp has 2 use cases
>
> 1) monitor proofing
> 2) print proofing
>
> yet it only has RGB and CMYK choices for working spaces
>
> I don't know if Photoshop or other software has a CIE colorimetric
> choice for working space, but in order to measure and track color it
> would be a lot easier to have one
>
> I know there are issues like gamut differences and rendering intents
>
> but if you want to measure the colorimetry of the monitor or proof and
> match it to the print, you need to start with CIE, not RGB or CMYK,
> ideally CIECAM but ICC has not gone there yet as far as I know


The gimp bug report and feature request list is here:

https://bugzilla.gnome.org/buglist.c...t%3A%22GIMP%22

 
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Dale
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      11-15-2012
On 11/14/2012 09:35 AM, Floyd L. Davidson wrote:
> Thomas Richter <(E-Mail Removed)-berlin.de> wrote:
>> Am 14.11.2012 05:56, schrieb Dale:
>>> gimp has 2 use cases
>>>
>>> 1) monitor proofing
>>> 2) print proofing
>>>
>>> yet it only has RGB and CMYK choices for working spaces
>>>
>>> I don't know if Photoshop or other software has a CIE colorimetric
>>> choice for working space, but in order to measure and track color it
>>> would be a lot easier to have one
>>>
>>> I know there are issues like gamut differences and rendering intents
>>>
>>> but if you want to measure the colorimetry of the monitor or proof and
>>> match it to the print, you need to start with CIE, not RGB or CMYK,
>>> ideally CIECAM but ICC has not gone there yet as far as I know

>>
>> The gimp bug report and feature request list is here:
>>
>> https://bugzilla.gnome.org/buglist.c...t%3A%22GIMP%22

>
> There is no bug though.
>
> The "RGB" and "CMYK" labels are just that, labels for
> two selectable workspaces that the user can easily
> switch between.
>
> But the workspace assigned to either of those two labels
> can be
> 1) virtually anything the system administrator
> has installed and made available, or
> 2) anything the user chooses to install privately.
>
> Any user that wants to use a different workspace merely
> needs to download whatever it is and install it. In
> GIMP, select the Edit->Preferences->Color Management
> menu. Both the "RGB" and "CMYK" profile options have a
> selection box, and the last option in either box is to
> "Select color profile from disk". Once a profile has
> been selected it will then show up as one of the
> available options and choosing it will not require
> locating it again.
>
> Sources for such profiles include LCMS, Argyll, and others.
>
>



you are right, my post was not a bug report, I was trying to prompt a
feature discussion

RGB aand CMYK are sensitometric and densitrometric spaces respectively,
and are linear withh with respect to light

I was suggesting a colorimetric working space like CIELAB or CIELUV
because delta E* is linear with just noticeable differences of the eye
and can be measured with a colorimeter or spectrophotometer or
spectroradiometer

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Dale
 
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Dale
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      11-15-2012
On 11/14/2012 07:11 PM, Dale wrote:
> On 11/14/2012 09:35 AM, Floyd L. Davidson wrote:
>> Thomas Richter <(E-Mail Removed)-berlin.de> wrote:
>>> Am 14.11.2012 05:56, schrieb Dale:
>>>> gimp has 2 use cases
>>>>
>>>> 1) monitor proofing
>>>> 2) print proofing
>>>>
>>>> yet it only has RGB and CMYK choices for working spaces
>>>>
>>>> I don't know if Photoshop or other software has a CIE colorimetric
>>>> choice for working space, but in order to measure and track color it
>>>> would be a lot easier to have one
>>>>
>>>> I know there are issues like gamut differences and rendering intents
>>>>
>>>> but if you want to measure the colorimetry of the monitor or proof and
>>>> match it to the print, you need to start with CIE, not RGB or CMYK,
>>>> ideally CIECAM but ICC has not gone there yet as far as I know
>>>
>>> The gimp bug report and feature request list is here:
>>>
>>> https://bugzilla.gnome.org/buglist.c...t%3A%22GIMP%22

>>
>> There is no bug though.
>>
>> The "RGB" and "CMYK" labels are just that, labels for
>> two selectable workspaces that the user can easily
>> switch between.
>>
>> But the workspace assigned to either of those two labels
>> can be
>> 1) virtually anything the system administrator
>> has installed and made available, or
>> 2) anything the user chooses to install privately.
>>
>> Any user that wants to use a different workspace merely
>> needs to download whatever it is and install it. In
>> GIMP, select the Edit->Preferences->Color Management
>> menu. Both the "RGB" and "CMYK" profile options have a
>> selection box, and the last option in either box is to
>> "Select color profile from disk". Once a profile has
>> been selected it will then show up as one of the
>> available options and choosing it will not require
>> locating it again.
>>
>> Sources for such profiles include LCMS, Argyll, and others.
>>
>>

>
>
> you are right, my post was not a bug report, I was trying to prompt a
> feature discussion
>
> RGB aand CMYK are sensitometric and densitrometric spaces respectively,
> and are linear withh with respect to light
>
> I was suggesting a colorimetric working space like CIELAB or CIELUV
> because delta E* is linear with just noticeable differences of the eye
> and can be measured with a colorimeter or spectrophotometer or
> spectroradiometer
>


CIECAM would be better, of course you have to pick a standard CAM
(appearance) for the profile connection space to convert between CAMs

the current ICC perceptual connection space uses an ideal print for the
CAM, this is not ideal for transparent and translucent display materials
or additive systems, they have a larger gamut than a print and you have
to make up information when you render from the standard CAM (the print)
to these gamuts, maybe you can have choices for the standard CAM



--
Dale
 
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Dale
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      11-15-2012
On 11/14/2012 05:29 AM, Thomas Richter wrote:
> Am 14.11.2012 05:56, schrieb Dale:
>> gimp has 2 use cases
>>
>> 1) monitor proofing
>> 2) print proofing
>>
>> yet it only has RGB and CMYK choices for working spaces
>>
>> I don't know if Photoshop or other software has a CIE colorimetric
>> choice for working space, but in order to measure and track color it
>> would be a lot easier to have one
>>
>> I know there are issues like gamut differences and rendering intents
>>
>> but if you want to measure the colorimetry of the monitor or proof and
>> match it to the print, you need to start with CIE, not RGB or CMYK,
>> ideally CIECAM but ICC has not gone there yet as far as I know

>
> The gimp bug report and feature request list is here:
>
> https://bugzilla.gnome.org/buglist.c...t%3A%22GIMP%22
>


did you say before that gimp's CMM was 8bit?

8bit encompasses the visual range of colors, but processing, to meet
Nyquist would be 16bit or higher

I used to make color profiles and know that few have precision of 1 delta E*

I also know there is little difference between good enough color and
perfect color, and that some things are better off left to editing than
specification

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Dale
 
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Thomas Richter
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      11-15-2012
Am 15.11.2012 02:57, schrieb Dale:

>
> CIECAM would be better, of course you have to pick a standard CAM
> (appearance) for the profile connection space to convert between CAMs
>
> the current ICC perceptual connection space uses an ideal print for the
> CAM, this is not ideal for transparent and translucent display materials
> or additive systems, they have a larger gamut than a print and you have
> to make up information when you render from the standard CAM (the print)
> to these gamuts, maybe you can have choices for the standard CAM


First, this is a *PROFILE* connection space. It is unrelated to
*PERCEPTUAL* rendering. Once more!

Second, it is *UNRELATED* to ideal printing. The PCS has nothing to do
with printing, rendering intent, the material you print on or its
properties.

Third, the PCS doesn't have a "gamut". XYZ is able to represent all
colors, if you like to.
 
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Thomas Richter
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      11-15-2012
Am 15.11.2012 04:18, schrieb Dale:
> On 11/14/2012 05:29 AM, Thomas Richter wrote:


>
> did you say before that gimp's CMM was 8bit?


Yes, it's to my very knowledge .

> 8bit encompasses the visual range of colors, but processing, to meet
> Nyquist would be 16bit or higher


That's not a frequency, so it's not related to *Nyquist*. But yes,
depending on the steep of the tone mapping curves, you might get banding
(quantization artifacts) due to the limitation of the resolution.
 
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Dale
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      11-16-2012
On 11/15/2012 09:03 AM, Thomas Richter wrote:
> Am 15.11.2012 02:57, schrieb Dale:
>
>>
>> CIECAM would be better, of course you have to pick a standard CAM
>> (appearance) for the profile connection space to convert between CAMs
>>
>> the current ICC perceptual connection space uses an ideal print for the
>> CAM, this is not ideal for transparent and translucent display materials
>> or additive systems, they have a larger gamut than a print and you have
>> to make up information when you render from the standard CAM (the print)
>> to these gamuts, maybe you can have choices for the standard CAM

>
> First, this is a *PROFILE* connection space. It is unrelated to
> *PERCEPTUAL* rendering. Once more!
>
> Second, it is *UNRELATED* to ideal printing. The PCS has nothing to do
> with printing, rendering intent, the material you print on or its
> properties.
>
> Third, the PCS doesn't have a "gamut". XYZ is able to represent all
> colors, if you like to.



you are confusing the PCS with the CMM, the PCS does have rendering
choices that you make on input and output profiles

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Dale
 
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Thomas Richter
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      11-16-2012
Am 16.11.2012 01:59, schrieb Dale:
> On 11/15/2012 09:03 AM, Thomas Richter wrote:
>> Am 15.11.2012 02:57, schrieb Dale:
>>
>>>
>>> CIECAM would be better, of course you have to pick a standard CAM
>>> (appearance) for the profile connection space to convert between CAMs
>>>
>>> the current ICC perceptual connection space uses an ideal print for the
>>> CAM, this is not ideal for transparent and translucent display materials
>>> or additive systems, they have a larger gamut than a print and you have
>>> to make up information when you render from the standard CAM (the print)
>>> to these gamuts, maybe you can have choices for the standard CAM

>>
>> First, this is a *PROFILE* connection space. It is unrelated to
>> *PERCEPTUAL* rendering. Once more!
>>
>> Second, it is *UNRELATED* to ideal printing. The PCS has nothing to do
>> with printing, rendering intent, the material you print on or its
>> properties.
>>
>> Third, the PCS doesn't have a "gamut". XYZ is able to represent all
>> colors, if you like to.

>
>
> you are confusing the PCS with the CMM, the PCS does have rendering
> choices that you make on input and output profiles


*Sigh*, no I'm not confusing this. I've already written CMMs, if you
care. The PCS does not have rendering choices in the same sense that the
R^3 does not have vector choices. It is the CMM that can implement
various rendering intents.

 
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Martin Leese
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      11-16-2012
Dale is just a troll. Please stop feeding
the trolls.

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Regards,
Martin Leese
E-mail: http://www.velocityreviews.com/forums/(E-Mail Removed)-mail.INVALID
Web: http://members.tripod.com/martin_leese/
 
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