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Gradient of a level set function [message #91352]

Thu, 02 July 2015 07:34

Shaktivel Pillai
Messages: 16
Registered: June 2015

Junior Member

i have a fits image with me ;double= array[4096,4096]

i have read the image using
img=readfits('filename.fts')

s = mean(img)

I am using the value of 's' as threshold.

Now i want to define the level set function;

'u' is the level set function.

u = img - s

Now i want to find the gradient of the level set function 'u'.

So;
uxy= gradient(u)

But im getting

% Variable is undefined: Gradient.

Can anyone help me out in this..
thanks

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Re: Gradient of a level set function [message #91353 is a reply to message #91352]

Thu, 02 July 2015 07:43

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

SP writes:

>
> i have a fits image with me ;double= array[4096,4096]
>
> i have read the image using
> img=readfits('filename.fts')
>
> s = mean(img)
>
> I am using the value of 's' as threshold.
>
> Now i want to define the level set function;
>
> 'u' is the level set function.
>
> u = img - s
>
> Now i want to find the gradient of the level set function 'u'.
>
> So;
> uxy= gradient(u)
>
> But im getting
>
> % Variable is undefined: Gradient.
>
> Can anyone help me out in this..

The function GRADIENT (which must be something you have written or found
somewhere, because it doesn't come in the "normal" IDL distribution)
doesn't appear to be on your IDL path where it can be found. Add
whatever directory the gradient.pro file is in to your IDL path. Then,
restart IDL and you will be good to go.

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.")

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