[vtkusers] How to map negative grayscale to color?
David Gobbi
david.gobbi at gmail.com
Tue Mar 8 23:35:08 EST 2016
No, that isn't necessary.
On Tue, Mar 8, 2016 at 9:29 PM, Liu_tj <tjlp at netease.com> wrote:
> Hi,David,
>
> Do I need to set the LookupTable to vtkImageMapToWindowLevelColors which
> is returned by vtkImageViewer2::GetWindowLevels() instead of create a new
> vtkImageMapToColors?
>
> BR,
> Thanks
>
>
> 在2016-03-09，"David Gobbi" <david.gobbi at gmail.com> 写道：
>
> -----原始邮件-----
> *发件人:*"David Gobbi" <david.gobbi at gmail.com>
> *发送时间:*2016年03月9日 星期三
> *收件人:*"Liu_tj" <tjlp at netease.com>
> *主题:*Re: Re: Re: [vtkusers] How to map negative grayscale to color?
>
>
> Hi Liu Peng,
>
> Do you want to show a gray image underneath, and the color image
> on top? I'm not sure if vtkImageViewer works property if you add
> more than one image.
>
> You should add a "print" statement of some kind to your code to
> print the values of scalarrange, to be sure they are correct.
>
> Don't call colormap.Build() after setting your own values for the table,
> or it might overwrite the values that you have set. If you call it at all,
> call it immediately after SetNumberOfTableValues(), before you set
> any of your own values.
>
> The range on the final for() loop should be the following:
> for (int i = (int)(threshhold[1]) + 1; i <= (int)(scalarrange[1]); i++)
>
> Also, if you want the beyond-threshold values to be transparent
> instead of black, then set the alpha component to zero:
>
> for (int i = (int)(scalarrange[0]); i < (int)(threshhold[0]); i++)
> {
> colormap.SetTableValue(i - (int)scalarrange[0], 0.0, 0.0, 0.0, 0.0);
> }
>
> - David
>
>
> On Tue, Mar 8, 2016 at 9:40 AM, Liu_tj <tjlp at netease.com> wrote:
>
>> Hi, David,
>>
>> I follow your post and it doesn't work. The DICOM image shows no color,
>> just gray image. Could you have a look at my code below? I use a
>> vtkImageView2 to display the DICOM image. The code is c# by Activiz .NET.
>> The scalar range of test image is [-1024,3071]. I want to show the gray
>> scale at [1000,3000] to green. The function GrayToColors() maps gray scale
>> to color, it is called by Display().
>>
>> private void Display(vtkRenderWindow aRenderWindow, vtkAlgorithmOutput
>> aData)
>> {
>> if (aData == null)
>> return;
>>
>> m_imageViewer = vtkImageViewer2.New();
>> m_imageViewer.SetInputConnection(aData);
>> switch (m_sliceDirection)
>> {
>> case Direction.AXIAL:
>> m_imageViewer.SetSliceOrientationToXY();
>> break;
>> case Direction.CORONAL:
>> m_imageViewer.SetSliceOrientationToYZ();
>> break;
>> case Direction.SAGITTAL:
>> m_imageViewer.SetSliceOrientationToXZ();
>> break;
>> default:
>> break;
>> }
>>
>> m_imageViewer.GetSliceRange(ref m_minSliceNumber, ref
>> m_maxSliceNumber);
>> m_interactorStyle = vtkInteractorStyleImage.New();
>> m_interactorStyle.MouseWheelForwardEvt += new
>> vtkObject.vtkObjectEventHandler(interactor_MouseWheelForwardEvt);
>> m_interactorStyle.MouseWheelBackwardEvt += new
>> vtkObject.vtkObjectEventHandler(interactor_MouseWheelBackwardEvt);
>>
>>
>> aRenderWindow.GetInteractor().SetInteractorStyle(m_interactorStyle);
>> aRenderWindow.GetRenderers().InitTraversal();
>>
>> m_renderer = aRenderWindow.GetRenderers().GetFirstRenderer();
>> m_renderer.SetBackground(0.0, 0.0, 0.0);
>>
>> m_imageViewer.SetRenderWindow(aRenderWindow);
>> m_currentSlice = m_minSliceNumber + (m_maxSliceNumber -
>> m_minSliceNumber) / 2;
>> m_imageViewer.SetSlice(m_currentSlice);
>>
>> double[] scalarrange = new double[2];
>> scalarrange = m_imageViewer.GetInput().GetScalarRange();
>> double[] threshhold = new double[2];
>> threshhold[0] = 1000;
>> threshhold[1] = 3000;
>> m_imageViewer.Render();
>> GrayToColors(m_renderer, aData, scalarrange, threshhold);
>>
>> m_imageViewer.Render();
>> }
>>
>> private void GrayToColors(vtkRenderer renderer,
>> vtkAlgorithmOutput data, double[] scalarrange, double[] threshhold)
>> {
>> vtkLookupTable colormap = vtkLookupTable.New();
>> int number = (int)(scalarrange[1] - scalarrange[0] + 1);
>> colormap.SetRange(scalarrange[0], scalarrange[1]);
>> colormap.SetNumberOfTableValues(number);
>>
>> for (int i = (int)(scalarrange[0]); i < (int)(threshhold[0]);
>> i++)
>> {
>> colormap.SetTableValue(i - (int)scalarrange[0], 0.0, 0.0,
>> 0.0, 1.0);
>> }
>> for (int i = (int)(threshhold[0]); i <= (int)(threshhold[1]);
>> i++)
>> {
>> colormap.SetTableValue(i - (int)scalarrange[0], 0.0, 1.0,
>> 0.0, 1.0);
>> }
>> for (int i = (int)(threshhold[1]); i < (int)(scalarrange[1]);
>> i++)
>> {
>> colormap.SetTableValue(i - (int)scalarrange[0], 0.0, 0.0,
>> 0.0, 1.0);
>> }
>> colormap.Build();
>>
>> vtkImageMapToColors colormapper = vtkImageMapToColors.New();
>> colormapper.SetInputConnection(data);
>> colormapper.SetLookupTable(colormap);
>> colormapper.Update();
>>
>> vtkImageActor colormapActor = vtkImageActor.New();
>> colormapActor.SetInput(colormapper.GetOutput());
>> renderer.AddActor(colormapActor);
>> renderer.ResetCamera();
>> renderer.Modified();
>> }
>>
>> Thanks
>>
>> 在2016-03-08，"David Gobbi" <david.gobbi at gmail.com> 写道：
>>
>> -----原始邮件-----
>> *发件人:*"David Gobbi" <david.gobbi at gmail.com>
>> *发送时间:*2016年03月8日 星期二
>> *收件人:*"Liu_tj" <tjlp at netease.com>
>> *抄送:*"vtkusers" <vtkusers at vtk.org>
>> *主题:*Re: Re: [vtkusers] How to map negative grayscale to color?
>>
>>
>> Hi Liu Pen,
>>
>> That's because I forgot to include the index argument in the call to
>> SetTableValue:
>>
>> table->SetRange(-1024, 4095);
>> table->SetNumberOfTableValues(4095 + 1024 + 1);
>> for (int i = -1024; i < -10; i++) {
>> table->SetTableValue(i + 1024, 0.0, 0.0, 0.0, 1.0);
>> }
>>
>> The table index must start at zero. The call to SetRange(-1024, 4095)
>> causes the scalar value -1024 to map to table index 0. In the "for" loop,
>> i is the scalar value.
>>
>> - David
>>
>>
>> On Tue, Mar 8, 2016 at 7:27 AM, Liu_tj <tjlp at netease.com> wrote:
>>
>>> Hi, David,
>>>
>>> When I try, a lot of errors are popup: "Can't set the table value for
>>> negative index".
>>>
>>> Seems the negative grayscale needs some transformation.
>>>
>>> Thanks
>>> Liu Peng
>>>
>>>
>>> 在2016-03-08，"David Gobbi" <david.gobbi at gmail.com> 写道：
>>>
>>> -----原始邮件-----
>>> *发件人:*"David Gobbi" <david.gobbi at gmail.com>
>>> *发送时间:*2016年03月8日 星期二
>>> *收件人:*"Liu_tj" <tjlp at netease.com>
>>> *抄送:*"vtkusers" <vtkusers at vtk.org>
>>> *主题:*Re: [vtkusers] How to map negative grayscale to color?
>>>
>>> Hi Liu Peng,
>>>
>>> You can set individual values in the lookup table,
>>> in order to precisely map certain scalar values to
>>> specific colors:
>>>
>>> table->SetRange(-1024, 4095);
>>> table->SetNumberOfTableValues(4095 + 1024 + 1);
>>> for (int i = -1024; i < -10; i++) {
>>> table->SetTableValue(0.0, 0.0, 0.0, 1.0);
>>> }
>>> for (int i = -10; i <= 200; i++) {
>>> table->SetTableValue(0.0, 1.0, 0.0, 1.0);
>>> }
>>> etcetera.
>>>
>>> - David
>>>
>>>
>>> On Mon, Mar 7, 2016 at 9:31 AM, Liu_tj <tjlp at netease.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> I try to use the vtkLookupTable to convert the grayscale to rgb color.
>>>> The image scalar range is [-1024,3071] returned by
>>>> vtkImageData::GetScalarRange(). Now I want to convert specific grayscale
>>>> range, for example, [-10,200] to one color, such as green (RGB is 0,1,0).
>>>> How to do that by vtkLookupTable? I have no idea what method should call:
>>>> SetNumberOfTableValues(), SetRange(), SetHueRange(), SetValueRange(). What
>>>> do "Hue" and "Value" stand for?
>>>>
>>>> BR,
>>>> Liu Peng
>>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
>
>
>
>
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