[Paraview] Gradient of an image

[Jérôme]

Hi David,
I think that your image has a 3-components data array, such as RGB.
ParaView "Gradient" filter is based on vtkImageGradient which expects
a 1-component image. You can
- convert your image in grey level with a third party software,
- use the calculator to compute a norm of the input image,
- enable the vtkImageMagnitude or vtkImageLuminance in ParaView (I
already did it here: http://github.com/jeromevelut/Peavip, but it
seems that vtkImageMagnitude needs some update...)

HTH
Jerome

2011/3/2 David Doria <daviddoria at gmail.com>:
> If I open a png file, the Gradient filter is grayed out. Is there a way to
> compute the gradient of such an image file?
>
> David
>
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