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Re: Function BYTSCL [message #24634 is a reply to message #24633]

Tue, 10 April 2001 07:44

Liam E. Gumley
Messages: 378
Registered: January 2000

Senior Member

Steffen Kernchen wrote:
> what function(s) can I use instead of BYTSCL?
> I have an array and I want to transform it to get a better contrast.
> But I should NOT use BYTSCL.... :(

It sounds like you want to do something other than selecting the minimum
and maximum array values for the scaling range used in BYTSCL. How about
trying histogram clipping?

(1) Compute a histogram for the image at N (say N=100) intervals between
the minimum and maximum array values.

(2) From the low end of the histogram, find the histogram bin where X
percent (say X=2) of the total number of array elements (pixels) lie to
the *left* of the current bin. The data value for this bin becomes the
minimum of the scaling range. Perform a similar search from the high end
of the histogram to obtain the maximum of the scaling range.

(3) Now use BYTSCL with the derived scaling range to create a contrast
enhanced image.

Other functions that will be useful in this exercise are HISTOGRAM and
TOTAL.

Cheers,
Liam.
http://cimss.ssec.wisc.edu/~gumley

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[Message index]

		Re: Function BYTSCL By: marc schellens[1] on Tue, 10 April 2001 18:20
		Re: Function BYTSCL By: davidf on Tue, 10 April 2001 16:43
		Re: Function BYTSCL By: davidf on Tue, 10 April 2001 10:18
		Re: Function BYTSCL By: Jaco van Gorkom on Tue, 10 April 2001 09:37
		Re: Function BYTSCL By: davidf on Tue, 10 April 2001 08:10
		Re: Function BYTSCL By: Liam E. Gumley on Tue, 10 April 2001 07:44
		Re: Function BYTSCL By: Steffen Kernchen on Tue, 10 April 2001 07:42
		Re: Function BYTSCL By: davidf on Tue, 10 April 2001 07:30
		Re: Function BYTSCL By: Jaco van Gorkom on Tue, 10 April 2001 07:18
		Re: Function BYTSCL By: davidf on Tue, 10 April 2001 06:55
		Re: Function BYTSCL By: marc schellens[1] on Tue, 10 April 2001 03:08
		Re: Function BYTSCL By: Steffen Kernchen on Tue, 10 April 2001 03:51
		Re: Function BYTSCL By: davidf on Tue, 10 April 2001 03:17

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