[vtkusers] Rendering raw X-ray problem

[Jens Fisseler]

Hi John,

> I'm having difficulty displaying X-rays in raw file format. To display the 
> image in the render window vtkImageActor demands that the scalar type of the 
> image be set to Unsigned Character. Yet this appears to alter the display 
> colouring. Firstly can anybody explain why the image is being altered and how 
> can I overcome this?? Really would appreciate some help on this. It's doing 
> my head.. Ta

I ran into the same problem during my first attempts with VTK some time
ago. The scalar values of your raw image probably contain values greater
than 255, the maximum value an unsigned char can represent. So the
higher bits of some pixels get truncated and you get color distortions.

My solution to this problem was to find the maximum scalar value and to
scale the interval [0,max] to the interval [0,255]. But perhaps someone
has a better solution?

	Jens

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