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Re: advanced image enhancement [message #32481 is a reply to message #32480]

Mon, 14 October 2002 09:51

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

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.

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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