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Re: advanced image enhancement [message #32482 is a reply to message #32481]

Mon, 14 October 2002 09:55

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

"Liam E. Gumley" wrote:
>
> David Oesch wrote:
>> Is there any other possibility to enhance the content of an bytarr
>> image? I tried BYTSCL and HIST_EQUAL, but ?m actually lokking for a Root
>> enhancement, also known as a logarithmic transform, which particularly
>> effective with images whose grey level distribution exhibits right
>> skewness. The root enhancement stretches the dynamic range of the low
>> end of the image while compressing its high end. It tends to lend an
>> overall brightening to the resultant image.Has anyone implemented such
>> an enhancement in IDL?
>
> Here's a simple example of a square root enhancement:
>
> a = dist(256)
> scale = (a - min(a)) / (max(a) - min(a))
> tv, byte(255.0 * scale) ; linear enhancement
> tv, byte(255.0 * sqrt(scale)) ; square root enhancement
>
> For extra credit, turn this into a function that accepts MIN, MAX,
> BOTTOM, and NCOLORS keywords.

I should have check the User Libraries first:

http://www.astro.washington.edu/deutsch-bin/getpro/library13 .html?SQRTSCL

Cheers,
Liam.
Practical IDL Programming
http://www.gumley.com/

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[Message index]

		Re: advanced image enhancement By: David Oesch on Mon, 14 October 2002 09:23
		Re: advanced image enhancement By: Liam E. Gumley on Mon, 14 October 2002 09:51
		Re: advanced image enhancement By: Liam E. Gumley on Mon, 14 October 2002 09:55
		Re: advanced image enhancement By: David Fanning on Mon, 14 October 2002 08:30

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