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#11
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gimp and ICC color working spaces
Dale is just a troll. Please stop feeding
the trolls. -- Regards, Martin Leese E-mail: LID Web: http://members.tripod.com/martin_leese/ |
#12
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gimp and ICC color working spaces
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? -- Dale |
#13
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gimp and ICC color working spaces
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 -- Dale |
#14
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gimp and ICC color working spaces
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 -- Dale |
#15
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gimp and ICC color working spaces
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 -- Dale |
#16
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gimp and ICC color working spaces
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? |
#17
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gimp and ICC color working spaces
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 -- Dale |
#18
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gimp and ICC color working spaces
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. |
#19
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gimp and ICC color working spaces
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 -- Dale |
#20
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gimp and ICC color working spaces
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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