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log scale colorbar in IDL 8.0 [message #76113]

Tue, 17 May 2011 13:25

Kim
Messages: 19
Registered: January 2009

Junior Member

Hello,

I have just started using the new graphics routines in IDL 8.0/8.1 and
am trying to incorporate them into an extensive set of customized
plotting and image type routines. I am able to use the IMAGE function
to display some log-normally distributed data, however I am unable to
create a colorbar that reflects the log-transformed data.

Here is a simplified example:
; Read the data array
; Convert the scaled float array (using ALOG10) to a byte array
im = IMAGE(bytedata)
cb =
COLORBAR(target=im,tickvalues=[0.01,0.03,0.1,0.3,1.0,3.0,10. 0,30.0],tickname=['.
01','.03','.1','.3','1','3','10','30'], title='Log Data')

Some specific questions:
1) How do you scale the color bar so that it reflects the scaled data?
2) If tickvalues are supplied, can you also input ticknames? In the
above example, the supplied ticknames are not used and instead the
ticknames are derived from the tickvalues. The only way I have been
able to use the ticknames is to remove the tickvalues keyword.
3) Is it possible to set minimum and maximum color or value ranges?
For example, in one of my commonly used rgb_tables, the 0 value is
black and above 250 are various shades of gray. How do I set it so
that mincolor=1 and maxcolor=250?
4) Is it possible to create a colorbar that is independent of some
specified data? It would be very useful to be able to create a
colorbar just using a user supplied data range instead of being
directly linked to a specfic data field. There are times when I need
to create stand alone colorbars and I can't figure out how to do this
with the COLORBAR function.

Thank you for your assistance,
Kim

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[Message index]

		log scale colorbar in IDL 8.0 By: Kim on Tue, 17 May 2011 13:25
		Re: log scale colorbar in IDL 8.0 By: David Fanning on Thu, 19 May 2011 13:26
		Re: log scale colorbar in IDL 8.0 By: pgrigis on Thu, 19 May 2011 12:36
		Re: log scale colorbar in IDL 8.0 By: David Fanning on Thu, 19 May 2011 11:00
		Re: log scale colorbar in IDL 8.0 By: pgrigis on Thu, 19 May 2011 10:52
		Re: log scale colorbar in IDL 8.0 By: David Fanning on Thu, 19 May 2011 09:53
		Re: log scale colorbar in IDL 8.0 By: David Fanning on Thu, 19 May 2011 09:42
		Re: log scale colorbar in IDL 8.0 By: David Fanning on Thu, 19 May 2011 09:02
		Re: log scale colorbar in IDL 8.0 By: pgrigis on Thu, 19 May 2011 08:53
		Re: log scale colorbar in IDL 8.0 By: davide.fedele on Thu, 12 March 2015 06:36

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