Hi,<div><br></div><div>When I show an image used vtkInteractorStyleImage, l<span style="font-family: 'lucida Grande', Verdana, 'Microsoft YaHei'; line-height: 23.8px;">eft button down and move, the ColorLevel of image will changing. I want to turn off the observer of </span><font face="lucida Grande, Verdana, Microsoft YaHei"><span style="line-height: 23.8px;">"MouseMoveEvent" and write the follow code. But it do not work. So anyone can tell me how to turn off the observer or turn off this function.</span></font></div><div><font face="lucida Grande, Verdana, Microsoft YaHei"><span style="line-height: 23.8px;"><br></span></font></div><div><font face="lucida Grande, Verdana, Microsoft YaHei"><span style="line-height: 23.8px;">cpp code:</span></font></div><div><font face="lucida Grande, Verdana, Microsoft YaHei"><span style="line-height: 23.8px;"><div><span class="Apple-tab-span" style="white-space: pre;"> </span>vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =</div><div><span class="Apple-tab-span" style="white-space:pre">            </span>vtkSmartPointer<vtkRenderWindowInteractor>::New();</div><div><span class="Apple-tab-span" style="white-space:pre">     </span>vtkSmartPointer<vtkInteractorStyleImage> imagestyle =</div><div><span class="Apple-tab-span" style="white-space:pre">          </span>vtkSmartPointer<vtkInteractorStyleImage>::New();</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre">      </span>imagestyle->RemoveObservers(vtkCommand::MouseMoveEvent);</div><div><span class="Apple-tab-span" style="white-space:pre">  </span>//imagestyle->RemoveAllObservers();</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre">      </span>renderWindowInteractor->SetInteractorStyle(imagestyle);</div><div><span class="Apple-tab-span" style="white-space:pre">   </span>renderWindowInteractor->SetRenderWindow(renderWindow);</div><div><span class="Apple-tab-span" style="white-space:pre">    </span>renderWindowInteractor->Initialize();</div><div><span class="Apple-tab-span" style="white-space: pre;">   </span>renderWindowInteractor->Start();</div><div><br></div><div>Thanks,</div><div>Yihui Cao</div></span></font></div>