[vtkusers] vtkImagePlaneWidget contrast control

[somi]

Hi Jothy,
On digging further, I found the right click was linked to
vtkImagePlaneWidget::WindowLevel

Where window size and leve of the histogram were calculated and modified
based on mouse movements, to get rmin and rmax .
Finally , the lookuptable was modified LookupTable->SetTableRange( rmin,
rmax ); to adjust brightness/contrast.

So, I am planning to do the following:

from my vtkImagePLanewidget I would  GetLookupTable () and set its table
range rmin/rmax based on the Qt slider.
However I am not very clear between the relation of brightness/contrast
and   rmin/rmax in  LookupTable->SetTableRange( rmin, rmax );

I think the window/level refer to the following in a histogram:

             ____________
            /
           /
__________/
         | ^ |
           L
         <-W->


and they are related to brightness/contrast by the following:

   minval = min(image)
   maxval = max(image)
   level = (1-brightness/100.)*(maxVal - minVal) + minVal
   window = (1-contrast/100.)*(maxVal - minVal)
where brightness/contrast can vary from 0 to 100.

So what value should I use for rmin/rmax in LookupTable->SetTableRange(
rmin, rmax ); ?

Regards,
Somi

On Fri, Apr 30, 2010 at 11:29 AM, Jothy <jothybasu at gmail.com> wrote:

> I don't have exact answer for this. But , I think you need to
> manipulate the observers.HAve a look at this
>
> http://www.cmake.org/Wiki/VTK_Examples#User_Interaction
>
> Jothy
>
> On Fri, Apr 30, 2010 at 3:58 PM, somi <seesomi at gmail.com> wrote:
> > Hi Jothy,
> > I want the brightness/control through a user control slider (in Qt). I
> also
> > show the surface overlaid over the image plane widget
> >
> >  Which function should I override to implement my own brightness/contrast
> > control ? I didn't find anything specific @
> > http://www.vtk.org/doc/nightly/html/classvtkInteractorStyleImage.html
> >
> > Also while playing with the interactor, I noticed that if my mouse is
> over
> > an image and I drag left/right I can adjust contrast and if I click and
> drag
> > up/down I can adjust contrast.
> > Do I have to imement my own interactor style and override right click ?
> > Isn't there any SetContrast/SetBrightness interface ?
> >
> > Regards,
> > Somi
> >
> >
> >
> > On Fri, Apr 30, 2010 at 10:44 AM, Jothy <jothybasu at gmail.com> wrote:
> >>
> >> I think by  setting Interacto Style to InteractorStyleToImage
> >>
> >> Jothy
> >>
> >> On Fri, Apr 30, 2010 at 3:31 PM, somi <seesomi at gmail.com> wrote:
> >> > Hi,
> >> > I have a 3D volume (vtkImage) which I show through 3 orthogonal
> >> > vtkImagePlaneWidgets. How can I add brightness and contrast control to
> >> > this
> >> > widget ?
> >> >
> >> > Regards, Somi
> >> >
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