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Re: How-to? color png [message #27625 is a reply to message #27624]

Tue, 30 October 2001 15:24

Mark Hadfield
Messages: 783
Registered: May 1995

Senior Member

From: "Andrew Cool" <andrew.cool@dsto.defence.gov.au>
> "Bernard K." wrote:
>>
>> I tried all the combinations proposed and they all work nicely. For the
>> surface I plot (and on my super-dupper mac :-) with the number of
>> colors used set to 256) the output I prefer is obtained by:
>>
>> tvlct, r, g, b, /get
>> and
>> write_png, 'image.png', datar,r,g,b
>> However I have to set decomposed to 1.
>
> Ockam's Razor wins again.

Ockam's Razor may help in understanding the universe but I don't think it
helps with IDL, which is *much* more complicated.

Or to put it another way, if David didn't spend his time writing code that
copes with *any* combination of colour depths, colour models, device
settings and IDL versions, then what would he do with his time?

Actually, there is a limitation with the above method. When the colour depth
is 24-bit, it is possible to issue successive graphics command to the same
window with different colour tables. In fact it might even be useful, eg:

loadct, 2 ; Load a nice colourful colour table
tv, ... ; Draw an image
loadct, 0 ; Load a boring grey-scale colour table
xyouts, ... ; Annotate the plot

This is arguably easier than using a single colour table & reserving some
indices for the annotation colours.

But if you then read the image with the above method, the tvlct command will
retrieve the current (grey-scale) colour table and the PNG file will look
rather boring.

So I'll use David's method. David hasn't shaved with Ockam's Razor for
years!

---
Mark Hadfield
m.hadfield@niwa.cri.nz http://katipo.niwa.cri.nz/~hadfield
National Institute for Water and Atmospheric Research

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[Message index]

		Re: How-to? color png By: David Fanning on Tue, 30 October 2001 16:08
		Re: How-to? color png By: Mark Hadfield on Tue, 30 October 2001 15:24
		Re: How-to? color png By: Andrew Cool on Tue, 30 October 2001 14:31
		Re: How-to? color png By: Bernard K. on Tue, 30 October 2001 01:16
		Re: How-to? color png By: Andrew Cool on Mon, 29 October 2001 14:52
		Re: How-to? color png By: David Fanning on Mon, 29 October 2001 14:24
		Re: How-to? color png By: David Fanning on Mon, 29 October 2001 14:19
		Re: How-to? color png By: Andrew Cool on Mon, 29 October 2001 13:45
		Re: How-to? color png By: David Fanning on Mon, 29 October 2001 13:41

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