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Re: IDLgrImage and the channel keyword [message #90168 is a reply to message #90167]

Wed, 04 February 2015 15:53

Jim Pendleton
Messages: 165
Registered: November 2011

Senior Member

On Wednesday, February 4, 2015 at 2:02:30 PM UTC-7, ronn kling wrote:
> All,
>
> Has anyone figured out how to use the channel keyword for IDLgrImage?
>
> If you try this
>
> file = 'E:\Program Files\Exelis\IDL84\examples\data\rose.jpg'
> im = read_image(file)
> xobjview, obj_new('IDLgrImage',im, channel='ff0000'x)
>
> What I expect to see is a red channel image, but instead I see cyan which is a combination of green and blue. So it is almost acting like a color subtraction. But if you try other hex combinations they don't work like subtractions either.
>
> Any ideas????
>
> Ronn Kling

Good question! It doesn't produce what I would expect from the documentation setting just the red channel in an RGB input image:

IDL> a = bytarr(3, 255, 255)
IDL> a[0, *, *] = 255B
IDL> xobjview, idlgrimage(a, channel = 'ff0000'x)
IDL> xobjview, idlgrimage(a, channel = '00ff00'x)
IDL> xobjview, idlgrimage(a, channel = '0000ff'x)

Compare with

IDL> xobjview, idlgrimage(a, channel = '000101'x)

Is Karl still out here on the internets?

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[Message index]

		IDLgrImage and the channel keyword By: ronn kling[1] on Wed, 04 February 2015 13:02
		Re: IDLgrImage and the channel keyword By: Jim Pendleton on Wed, 04 February 2015 15:53
		Re: IDLgrImage and the channel keyword By: Dick Jackson on Wed, 04 February 2015 16:29
		Re: IDLgrImage and the channel keyword By: ronn kling[1] on Wed, 11 March 2015 03:16

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