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Re: White and black colours appearing when selecting colour table [message #91969 is a reply to message #91965]

Thu, 24 September 2015 02:24

liam.steele
Messages: 13
Registered: September 2015

Junior Member

On Wednesday, 23 September 2015 20:57:41 UTC+1, David Fanning wrote:
> liam.steele@gmx.co.uk writes:
>
>> I am wanting to draw a certain number of contours, each with a different colour ranging from blue to red. However, when I select the colour table and set the number of colours, I get a random white and black line appearing.
>>
>> I've included a simple example below, and the resulting image I get can be found here: http://s7.postimg.org/bm8svkbnv/idl.png
>>
>> I know there is obviously something simple I'm forgetting to do, but I just can't think what it is!
>
> If you really *have* to use indexed color (and there has been no reason
> to since, I don't know, the turn of the century, probably), then you are
> going to have to load your color table before you try to do anything
> that uses those colors.
>
> You would find life SO much easier it you turned color decomposition on
> and just used Coyote Library routines to do your plotting. Everything
> will just *work* then, without you having to spend any time thinking
> about it. :-)
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
> Sepore ma de ni thue. ("Perhaps thou speakest truth.")

Thanks David.

I have always plotted this way though, and have never noticed a problem before.

In the example I provided, ccol[60] shows as white, and ccol[82] shows as black. So if I choose to use only 59 colours there is no problem, but any more and the white and then black lines show up.

I'm just stumped as to why it won't work. It has device,decomposed=0, has loaded a set number of colours, and has given them an index. Maybe I should just ignore it and do something else, but it's bugging me!

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[Message index]

		White and black colours appearing when selecting colour table By: liam.steele on Wed, 23 September 2015 08:38
		Re: White and black colours appearing when selecting colour table By: David Fanning on Wed, 23 September 2015 12:57
		Re: White and black colours appearing when selecting colour table By: liam.steele on Thu, 24 September 2015 02:24
		Re: White and black colours appearing when selecting colour table By: David Fanning on Thu, 24 September 2015 05:12
		Re: White and black colours appearing when selecting colour table By: liam.steele on Thu, 24 September 2015 05:41
		Re: White and black colours appearing when selecting colour table By: David Fanning on Thu, 24 September 2015 05:46
		Re: White and black colours appearing when selecting colour table By: David Fanning on Thu, 24 September 2015 05:55

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