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
> 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:
Thomas Richter <t...@math.tu-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:
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.
> Thomas Richter <t...@math.tu-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:
> 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
> On 11/14/2012 09:35 AM, Floyd L. Davidson wrote:
>> Thomas Richter <t...@math.tu-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:
>> 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
> 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:
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
> 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.
> 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.
>> 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
> 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.
> 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.
we kind of got off my original post, can gimp or do other osftwares have colorimetric working spaces like CIELAB, CIEXYZ, etc., as opposed to spaces like RGB and CMYK?
> 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.
a profile can be populated with 4 intents, perceptual relative to a print, maintain saturation, colorimetric and absolute colorimetric
the PCS is instantiated to represent the intents and conversion spaces chosen or specified
>> *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.
> a profile can be populated with 4 intents, perceptual relative to a
> print, maintain saturation, colorimetric and absolute colorimetric
> the PCS is instantiated to represent the intents and conversion spaces
> chosen or specified
No, it's not, for the last time! An *ICC profile* includes a rendering intent. It *also* defines a profile connection space, but the profile connection space has no rendering intent.
How often do I need to explain you that the PCS is just a common coordinate space to express colors both of the input and the display (or output) device?
The ICC profile contains enough information to convert from the device color space to the PCS and back. It defines the type of the PCS, it also defines the rendering intent which, again, defines the peculiarities in how to interpret the coordinate transformation (or how or where to find it). But the PCS is nothing but the coordinate frame in which colors are expressed. It doesn't have an intent. If coordinate transformations could be done in infinite precision, and if we wouldn't care about practical implementation limits, the PCS would not even matter. We could pick XYZ for everything and express coordinates always in XYZ.
The CMM is the piece of software that implements the coordinate transformation to and from the PCS. It implements the rendering, and by that also defines how to realize the rendering intent - it has some freedom.
But why the heck don't you just download the specs from color.org and read them yourselves?
> On 11/17/2012 06:05 AM, Thomas Richter wrote:
>> The ICC profile contains enough information to convert from the device
>> color space to the PCS and back
> the profile intent choices define the PCS and instantiate it in the CMM
> Am 18.11.2012 04:42, schrieb Dale:
>> On 11/17/2012 06:05 AM, Thomas Richter wrote:
>>> The ICC profile contains enough information to convert from the device
>>> color space to the PCS and back
>> the profile intent choices define the PCS and instantiate it in the CMM
> No, it doesn't.
then how does the CMM connect intent choice on both the input and output
> On 11/18/2012 04:32 AM, Thomas Richter wrote:
>> Am 18.11.2012 04:42, schrieb Dale:
>>> On 11/17/2012 06:05 AM, Thomas Richter wrote:
>>>> The ICC profile contains enough information to convert from the device
>>>> color space to the PCS and back
>>> the profile intent choices define the PCS and instantiate it in the CMM
>> No, it doesn't.
> then how does the CMM connect intent choice on both the input and output
Why don't you just download the ICC specs from color.org and study it?
The ICC profile defines how to map the device colorspace to the PCS by including tables and/or parameters for the transformation.
The PCS is constant, but depending on the ICC profile, more than one table/parameters exists how to implement the mapping. The CMM checks the rendering intent, and then picks table A, B or C that transforms the device colors to the PCS coordinates. The PCS stays always the same, typically XYZ. Despite this explicit dependency, the CMM may also (implicitly) make rendering-intent specific algorithmic choices, for example how to handle out-of-gammut colors or how to implement an adaption on the illumination source.
> On 20.11.2012 05:27, Dale wrote:
>> On 11/18/2012 04:32 AM, Thomas Richter wrote:
>>> Am 18.11.2012 04:42, schrieb Dale:
>>>> On 11/17/2012 06:05 AM, Thomas Richter wrote:
>>>>> The ICC profile contains enough information to convert from the device
>>>>> color space to the PCS and back
>>>> the profile intent choices define the PCS and instantiate it in the CMM
>>> No, it doesn't.
>> then how does the CMM connect intent choice on both the input and output
> Why don't you just download the ICC specs from color.org and study it?
> The ICC profile defines how to map the device colorspace to the PCS by
> including tables and/or parameters for the transformation.
> The PCS is constant, but depending on the ICC profile, more than one
> table/parameters exists how to implement the mapping. The CMM checks the
> rendering intent, and then picks table A, B or C that transforms the
> device colors to the PCS coordinates. The PCS stays always the same,
> typically XYZ. Despite this explicit dependency, the CMM may also
> (implicitly) make rendering-intent specific algorithmic choices, for
> example how to handle out-of-gammut colors or how to implement an
> adaption on the illumination source.
