[vtkusers] vtkImageErode3D

[Bill Lorensen]

Elena,

ImageDilateErode works on grayscale images, not binary images. The CT
image is a grayscale image. The Insight Toolkit (ITK) grayscale
erosion/dilation.

Perhaps you can tell us what you want to accomplish.

Bill

On Thu, Nov 28, 2013 at 3:34 AM, elena bresciani
<elena.bresciani87 at gmail.com> wrote:
> I tried to set different values of kernel size and erode/dilate values
> without seeing any difference in the output; also I added the Update() call
> and tried using he two filters separately, still no changes.
>
> here's my code (I'm using python):
>
> # imageReader is a vtkBMPReader
>
> # apply the dilate/erode filter to the image
>
> erode = vtk.vtkImageDilateErode3D()
> erode.SetInputConnection(imageReader.GetOutputPort())
> erode.SetErodeValue(3)
> erode.SetKernelSize(5, 5, 1)
> erode.ReleaseDataFlagOff()
> erode.Update()
>
> dilate = vtk.vtkImageDilateErode3D()
> dilate.SetInputConnection(erode.GetOutputPort())
> dilate.SetDilateValue(3)
> dilate.SetKernelSize(5, 5, 1)
> dilate.ReleaseDataFlagOff()
> dilate.Update()
>
> # create the actors one for the original image ad one for the
> # processed one
> originalActor = vtk.vtkImageActor()
> originalActor.GetMapper().SetInputConnection(imageReader.GetOutputPort())
>
> processedActor = vtk.vtkImageActor()
> processedActor.GetMapper().SetInputConnection(dilate.GetOutputPort())
>
> # rendering stuff...
>
>
> 2013/11/27 Jon Haitz Legarreta <jhlegarreta at vicomtech.org>
>>
>> Dear Elena,
>> another alternative would be to vary the kernel size to some extreme
>> values so that you can really be aware of any changes.
>> Another possibility would be to use the erode/dilate filters separately.
>> And yes, you are right, if you erode an object to the ground it cannot be
>> dilated anymore however hard you try.
>>
>> HTH,
>> JON HAITZ
>>
>>
>>
>> On 27 November 2013 13:29, Marco Nawijn <nawijn at gmail.com> wrote:
>>>
>>> Hi Elena,
>>>
>>> Although I probably cannot help you directly, I would advise you
>>> isolate your problem to the smallest compilable piece of code
>>> and post this so experts can take a look at it. One thing that
>>> bit me in the past is that ones you apply a filter, you have to
>>> a.) call Update() on it and b.) call GetOutput() to get the result
>>> you are looking for. Without seeing your code however it is
>>> difficult to judge.
>>>
>>> Kind regards,
>>>
>>> Marco
>>>
>>> P.S. There is nothing wrong with your english!
>>>
>>>
>>>
>>> On Wed, Nov 27, 2013 at 12:24 PM, elena bresciani
>>> <elena.bresciani87 at gmail.com> wrote:
>>>>
>>>> I'm getting started with vtk and I'm still unable to solve a lot of
>>>> problems.
>>>>
>>>> I'm trying to apply the vtk filter vtkImageDilateErode3D to a CT image
>>>> but I
>>>> can't obtain the result I'm looking for.
>>>> In fact I expect the result to be a at least slightly different image
>>>> but
>>>> the output is instead an image identical to the one given as input (I
>>>> even
>>>> checked subtracting the two images with vtkImageMathematics and after
>>>> the
>>>> operation there's really nothing left!).
>>>> I don't understand if the problem is in the setting of the Erode and
>>>> Dilate
>>>> values and in the kernel size or maybe in the function of the filter
>>>> itself,
>>>> i.e. I expect that the output image has something less compared to the
>>>> original one after erosion and dilatation (what has been eroded "to the
>>>> ground" canot be dilated back - is this correct?)
>>>>
>>>> Thank you in advance
>>>> Sorry for the bad english
>>>>
>>>> Elena
>>>>
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>>>
>>>
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>>
>
>
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