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Re: How to scale image in idl? [message #6218]

Thu, 16 May 1996 00:00

Thomas A. McGlynn
Messages: 23
Registered: March 1996

Junior Member

David Foster wrote:
>
> peter@hpl.hp.com (Peter Webb) wrote:
>>
>> Watcher (dliu@cs.tufts.edu) wrote:
>> : I've used tv and tvscl to display the image, however it is too honest to
>> : the size of the image itself. Is there a way to scale the image so that
>> : it fits the display window?
>>
>> Use CONGRID to interpolate the image matrix to the window size.
>
> You can also use EXPAND to change the size of an image. It's similar
> to CONGRID and I don't know which one is faster. They have slightly
> different options available.
>
> If the window size is an integer multiple of the image size
> then use the REBIN function as it is significantly faster,
> especially for large images.
>
> Dave Foster
> UCSD Brain Image Analysis Lab
> foster@bial1.ucsd.edu

But if you use REBIN (and maybe CONGRID) read the documentation carefully
and see if what happens to the last column/row is acceptable. When
data is expanded by an integral factor, the last column/row will be repeated
the integral number of times even if the other pixels are being interpolated.
I find the behaviour counter-intuitive but it is fully documented.

Tom McGlynn
tam@silk.gsfc.nasa.gov

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[Message index]

		Re: How to scale image in idl? By: Thomas A. McGlynn on Thu, 16 May 1996 00:00
		Re: How to scale image in idl? By: Rachel Howe on Thu, 16 May 1996 00:00
		Re: How to scale image in idl? By: Liam Gumley on Wed, 15 May 1996 00:00
		Re: How to scale image in idl? By: David Foster on Wed, 15 May 1996 00:00
		Re: How to scale image in idl? By: peter on Tue, 14 May 1996 00:00

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