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Is Lab color (L*a*b*) still relevant?

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  #61  
Old 05-01-2015, 09:08 PM
Benny Profane's Avatar
Benny Profane Benny Profane is offline
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Re: Is Lab color (L*a*b*) still relevant?

Quote:
Originally Posted by klev View Post
Quantization errors always exist in some way when dealing with numerical computations, assuming you permit any operations beyond addition and subtraction.
Wait.


What?


Quantization??
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  #62  
Old 05-02-2015, 01:48 AM
klev klev is offline
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Re: Is Lab color (L*a*b*) still relevant?

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Originally Posted by Benny Profane View Post
Wait.


What?


Quantization??
It's just a term in image processing that refers to reproducing something in a set of discrete steps. It's a slightly odd term to use there, because it comes from signal reconstruction where you have to fit a finite set of points to a continuous change in voltage. In this case we were referring to errors in assigning a discrete set of values to a given mapping, even though it didn't explicitly refer to signal reconstruction. It's still similar when you convert between color spaces, as it's done most commonly via linear transformation. It sounds like something weird, but it just means that they're only dealing with multiples of the original values. The new ones aren't dependent on the squares or higher powers of the old ones, which makes it a bit simpler.
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  #63  
Old 05-02-2015, 08:25 AM
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Benny Profane Benny Profane is offline
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Re: Is Lab color (L*a*b*) still relevant?

Does it have anything to do with a LUT?
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  #64  
Old 05-02-2015, 11:47 AM
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Re: Is Lab color (L*a*b*) still relevant?

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Originally Posted by Benny Profane View Post
Does it have anything to do with a LUT?
It could. But why attempt to explain this to someone again hijacking a thread and asking questions he has no intention of trying to understand. Is there a reason you come to such posts and add nothing useful to the conversation like your above question? Try using 'the Google'.
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  #65  
Old 05-02-2015, 03:26 PM
joe_7 joe_7 is offline
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Re: Is Lab color (L*a*b*) still relevant?

The main uses I've found for L*a*b are being able to sharpen the luminosity channel by itself, or blur the color information slightly. (The latter is great for big enlargements to make everything look smoother.)

Beyond that I never got much more into it though, and use it only as a final step.
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  #66  
Old 05-02-2015, 09:59 PM
pixaeiro pixaeiro is offline
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Re: Is Lab color (L*a*b*) still relevant?

Quote:
Originally Posted by klev
I'm pleased that someone used the correct number there (mantissa only rather than 2^32).
Ha Ha, yep... I am a programmer. Programming in float is way easier than uint8.
Quote:
Originally Posted by joe_7
The main uses I've found for L*a*b are being able to sharpen the luminosity channel by itself, or blur the color information slightly. (The latter is great for big enlargements to make everything look smoother.)
Yes, same me... but that is a very useful trick... and if you scale down the a and b channels from the center, you can also increase the saturation of the color...
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