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Archive 2013 · Profile Gamma Variants
  
 
RustyBug
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p.1 #1 · Profile Gamma Variants


I just noticed (quick, I'm not ... at times) that the profiles for ProPhoto RGB, Adobe RGB, sRGB, Apple RGB, Colormatch RGB and Wide Gamut RGB have 1.0 and 1.4 gamma variant options preset in CS6. I get the rationale for the 1.0 linear option, but what is the rationale for establishing a 1.4 gamma preset?

Also, I notice that the profile for CIE RGB does NOT have additional preset gamma variants. I realize that gamma can be adjusted to what ever you may desire (via other methods) it to be but I was just wondering if anyone knows the rationale for the 1.4 gamma presets and why CIE RGB would be the only RGB profile without the additional gamma variants of 1.0 and 1.4 (i.e. consistent with the other RGB gamma variant preset offerings)?



Mar 27, 2013 at 01:42 PM
Eyeball
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p.1 #2 · Profile Gamma Variants


Where are you seeing these profiles with the different gamma options, Kent?


Mar 27, 2013 at 02:30 PM
RustyBug
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p.1 #3 · Profile Gamma Variants


Edit>Assign Profile or Edit>Convert to Profile.
The regular culprits on top, then the laundry list of variants down below.

I'm assuming that since the regular gamma's range from 1.8 to 2.2 (appx 2.0), the 1.4 being the stepping stone (square root/stop) between linear and regular gamma ... but that's just hazarding a swag. Even that doesn't explain the exclusion to why there are no CIE RGB gamma variant presets.



Mar 27, 2013 at 02:39 PM
mshi
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p.1 #4 · Profile Gamma Variants


Here is the dump of my default gamma values reported. The talk can get very technical in-depth. But, let me put it in a very short version, the value that you choose to use is based on your intent. I have always modified gamma values on the fly based on what I intend to do with an image in whatever the color space, ie RGB, LAB or CMYK, that I choose.







Edited on Mar 27, 2013 at 03:03 PM · View previous versions



Mar 27, 2013 at 03:01 PM
 

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newhaven
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p.1 #5 · Profile Gamma Variants


I believe those are false profiles from the Dan Margulis extension.


Mar 27, 2013 at 03:02 PM
RustyBug
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p.1 #6 · Profile Gamma Variants


newhaven wrote:
I believe those are false profiles from the Dan Margulis extension.


That would make perfect sense (especially given Dan's perspective/teaching/style), since I just downloaded it this week ... thus the reason I never noticed them before and Dennis hadn't seen them yet.

Gotcha, thanks.

mshi wrote:
the value that you choose to use is based on your intent. I have always modified gamma values on the fly based on what I intend to do with an image in whatever the color space, ie RGB, LAB or CMYK, that I choose.


+1 @ image intent for gamma/space utilization.


Edited on Mar 27, 2013 at 03:16 PM · View previous versions



Mar 27, 2013 at 03:06 PM
mshi
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p.1 #7 · Profile Gamma Variants


here are some more in-depth discussions/video on gamma encoding if you need to learn more about it.

http://www.modelmayhem.com/po.php?thread_id=883513



Mar 27, 2013 at 03:15 PM
RustyBug
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p.1 #8 · Profile Gamma Variants


Thanks for the link, good stuff.

I think I was mostly bothered by why I'd missed the variants before.
That and what rationale ... insert Dan's name, and that pretty much explains it if you are already familiar with his thought processes.



Mar 27, 2013 at 03:17 PM





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