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gimp and ICC color working spaces

 
 
Dale
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      11-17-2012
On 11/16/2012 03:11 AM, Thomas Richter wrote:
> 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?

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Dale
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      11-17-2012
On 11/16/2012 03:11 AM, Thomas Richter wrote:
> 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






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Dale
 
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Dale
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      11-17-2012
On 11/16/2012 10:51 AM, Martin Leese wrote:
> Dale is just a troll. Please stop feeding
> the trolls.
>


go to alt.usenet.kooks and recommend me for a kook award

I haven't had one in years

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Dale
 
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Dale
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      11-17-2012
On 11/16/2012 08:27 PM, Dale wrote:
> On 11/16/2012 10:51 AM, Martin Leese wrote:
>> Dale is just a troll. Please stop feeding
>> the trolls.
>>

>
> go to alt.usenet.kooks and recommend me for a kook award
>
> I haven't had one in years
>


there IS a cabal

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Dale
 
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Thomas Richter
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      11-17-2012
On 17.11.2012 01:36, Dale wrote:

>> *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?




 
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Dale
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      11-18-2012
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

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Thomas Richter
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      11-18-2012
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.

 
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Dale
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      11-20-2012
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

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Thomas Richter
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      11-21-2012
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.

Greetings,
Thomas
 
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Dale
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      11-22-2012
On 11/21/2012 10:20 AM, Thomas Richter wrote:
> 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.
>
> Greetings,
> Thomas



I think I got it now, Thanks

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