| Re: zoom into float image data? [message #21917 is a reply to message #21907] |
Wed, 27 September 2000 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Andrew (amacphee@my-deja.com) writes:
> I've got arrays of float where the interesting data lies in a small
> range. For example, the raw data ranges from -123.45 to 5678.9,
> whilst the interesting stuff lies between 123.4 and 125.6. For each set
> the interesting data is not necesserily in the same range.
>
> I'm trying to write something that:
> 1) displays the image bytescaled;
> 2) uses xloadct to stretch the colour table to home in on the
> interesting data;
> 3) re-bytescales the data with new min and max values determined from
> the scaling of the colour table.
> 4) Iterate 3 and 4 until I've zoomed in on the interesting data.
>
> I thought I could use the numbers on the stretch bars in xloadct as
> feedback to re-bytescale my input data, but these numbers aren't
> returned by xloadct. I then thought I could use tvlct to read the rgb
> values after stretching, then use e.g. min(where(r>0)) and
> max(where(r<255)) to find how much I had stretched the table. However, I
> expect I would need to do the same for green and blue and I can't see
> then how this would correspond to the 'stretch' numbers in xloadct if
> the colour table wasn't linear in all three colours.
>
> Then I wondered if anyone else had gone around this loop and maybe had
> come up with a far slicker, tried and trusted solution :-)
I think my XStretch program is made to order. :-)
http://www.dfanning.com/programs/xstretch.pro
You will need XColors too, if you want to change color
tables:
http://www.dfanning.com/programs/xcolors.pro
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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