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[OM] Re: PhotoShop lens correction question

Subject: [OM] Re: PhotoShop lens correction question
From: Moose <olymoose@xxxxxxxxx>
Date: Sun, 05 Aug 2007 14:55:46 -0700
Chuck Norcutt wrote:
> Thanks.  Since the image didn't have layers
It is a JPEG on the web with three color channels (not layers, 
technically), although they are each exactly the same. At least that's 
how it ends up on my HD when I right click and select Save Image As.
>  to only option was to lie and say that a grayscale image was RGB.  
The only way that can be true is if CS3 somehow imports RGB JPEGs with 
identical channels as grayscale - or - if you converted the mode to 
grayscale yourself.
> That did make the lens correction option available but leaves me really 
> scratching my head.
If I convert the RGB8 image I get when I open the downloaded JPEG to 
grayscale, the Lens Correction is indeed not available.
> I can understand that lens correction would require RGB information to be 
> able to correct chromatic abberation but I would expect that if you entered 
> lens correction with a gray scale image that only chromatic abberation would 
> be unavailable once you entered the filter dialog. 
>   
That's what I would expect too, but it isn't the case, so why worry 
about it?

Odder than that, Curves has always worked backwards in grayscale too. 
Pull the curve up and to the left in RGB and the image gets lighter in 
the middle tones. Do the same with the same image in grayscale and it 
gets darker. An "S" curve increases contrast in RGB, decreases it in 
grayscale and a reverse "S" is needed to increase contrast in grayscale.

That doesn't make any sense to me either, but it's how the product 
works, and has for at least the last several versions.
> Completely blocking entry to the other correction functions doesn't make 
> sense.  And graying out options without explanations has always driven 
> me nuts.
It seems to me that we have a couple of significant choices in that area 
of life: Worry about it and be nuts and unhappy - or - don't worry about 
it and be sane and happy. The option of living in a world where 
everything makes sense in the way you would like it to is not an actual 
option.
>   Thanks again.
>   
You are so welcome.  ;-)

Moose

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