[vtkusers] Combination of two images

[David Gobbi]

Hi Adrien,

I'm sorry, I did not read your code carefully enough.

The append filter you need is vtkImageAppendComponents.

The SetInput() only sets the first input, not the second.
Do this instead:

app.SetInput(readerMask.GetOutput());
app.AddInput(opac.GetOutput());

blend.SetInput(readerImage.GetOutput());
blend.AddInput(app.GetOutput());

Hopefully that will make it work.

 - David

On Wed, Apr 13, 2011 at 7:54 AM, Adrien Marion
<adrien.marion at creatis.insa-lyon.fr> wrote:
> I added the correct lines below:
>
> opac = vtkImageThreshold();
> opac.SetInput(readerMask.GetOutput());
> opac.ThresholdByUpper(1);
> opac.ReplaceInOn();
> opac.ReplaceOutOn();
> opac.SetInValue(255);
> opac.SetOutValue(0);
> opac.Update();
>
> // Here opac is a binary image (0 or 255).
>
> app = vtkImageAppend();
> app.SetInput(readerMask.GetOutput());
> app.SetInput(opac.GetOutput());
> app.Update();
>
> blend = vtkImageBlend();
> blend.SetInput(readerImage.GetOutput());
> blend.SetInput(app.GetOutput());
> blend.Update();
>
> // blend is the same as opac, i.e. equal to 0 or 255
>
> Another tip or mistake to avoid ?
>
> Adrien
>
> Le 13/04/2011 15:45, David Gobbi a écrit :
>>
>> Oops, one other thing!
>>
>> When blending, the image with alpha comes second, not first:
>> blend.SetInput(currentImage);
>> blend.AddInput(app.GetOutput());
>>
>>  - David
>>
>>
>> On Wed, Apr 13, 2011 at 7:42 AM, David Gobbi<david.gobbi at gmail.com>
>>  wrote:
>>>
>>> Hi Adrien,
>>>
>>> The alpha mask should have values of 0 and 255:
>>> opac.ReplaceInOn();
>>> opac.ReplaceOutOn();
>>> opac.SetInValue(255);
>>> opac.SetOutValue(0);
>>>
>>>  - David
>>>
>>>
>>> On Wed, Apr 13, 2011 at 7:33 AM, Adrien Marion
>>> <adrien.marion at creatis.insa-lyon.fr>  wrote:
>>>>
>>>> Thank you David.
>>>> vtkImageStencil is not OK adding
>>>>
>>>> IS.SetInput(img);
>>>>
>>>> So I tried your second solution doing (test with python):
>>>>
>>>> opac = vtkImageThreshold();
>>>> opac.SetInput(img);
>>>> opac.ThresholdByUpper(1);
>>>> opac.SetInValue(1);
>>>> opac.Update();    // Thresholded image with 2 levels (0 and 1)
>>>>
>>>> app = vtkImageAppend();
>>>> app.SetInput(img);
>>>> app.SetInput(opac.GetOutput());
>>>> app.Update();    // Image with 2 components, the initial one (img) and
>>>> the
>>>> associated binary mask
>>>>
>>>> blend = vtkImageBlend();
>>>> blend.SetInput(app.GetOutput());
>>>> blend.SetInput(currentImage);
>>>> blend.Update();
>>>>
>>>> However, It does not provide the good combination. Did I wrote mistakes
>>>> ?
>>>> I do not understand how to say that the blend must take the second
>>>> component
>>>> of app (i.e. the binary mask) to decide if pixels have to be replaced.
>>>>
>>>> Adrien
>>>>
>>>> Le 13/04/2011 14:59, David Gobbi a écrit :
>>>>>
>>>>> Hi Pat,
>>>>>
>>>>> The vtkImageStencil filter can take two image inputs, try adding this:
>>>>>
>>>>>
>>>>>
>>>>> You can also combine the images without using stencils.  To do this,
>>>>> you would use vtkImageThreshold to generate your mask image, and then
>>>>> vtkImageAppend to append this mask to img as an alpha channel.  Then
>>>>> vtkImageBlend can be used to combine the images, it will use the alpha
>>>>> channel to decide which pixels to replace.  This method doesn't have
>>>>> any advantage compared to using stencils, it's just a different way of
>>>>> doing the same thing.
>>>>>
>>>>>  - David
>>>>>
>>>>> On Wed, Apr 13, 2011 at 6:42 AM, Adrien Marion
>>>>> <adrien.marion at creatis.insa-lyon.fr>    wrote:
>>>>>>
>>>>>> Hi,
>>>>>> I have two vtkImageData (called currentImage and img), each containing
>>>>>> values from 0 to 250.
>>>>>> I would like to combine these images to obtain a resulting image
>>>>>> (resImage)
>>>>>> doing for each pixel:
>>>>>> - if Mask == 0, resImage = currentImage
>>>>>> - else resImage = Mask
>>>>>>
>>>>>> I currently work with VTK wrapped version in Java and I cannot afford
>>>>>> a
>>>>>> triple loop with getScalarAsDoubleComponent to do that.
>>>>>>
>>>>>> Does someone have a simple solution to do that ?
>>>>>>
>>>>>> I already tried with vtkImageStencil but It does not give the good
>>>>>> solution:
>>>>>>
>>>>>>        vtkImageToImageStencil IIS = new vtkImageToImageStencil();
>>>>>>        IIS.SetInput(img);
>>>>>>        vtkImageStencil IS = new vtkImageStencil();
>>>>>>        IS.SetStencil(IIS.GetOutput());
>>>>>>        IS.SetInput(currentImage);
>>>>>>        IS.Update();
>>>>>>        result = IS.GetOutput();
>>>>>>
>>>>>> I think I did not understand how vtkImageStencil works.
>>>>>>
>>>>>> Thank you in advance for your help,
>>>>>> Adrien
>>>>>>
>>>>>> --
>>>>>> Adrien MARION, Docteur/PhD
>>>>>> Chercheur post-doctorant (ANR VIP)
>>>>>> Laboratoire CREATIS, INSA de Lyon
>>>>>> CNRS UMR 5220, INSERM U1044
>>>>>> Bâtiment Blaise Pascal, 4ème étage
>>>>>> 7, avenue Jean Capelle
>>>>>> 69621 Villeurbanne cedex FRANCE
>>>>>> Tel : (+33) 4 72 43 87 86
>>>>>> Fax:  (+33) 4 72 43 85 26
>>>>>> e-mail : adrien.marion at creatis.insa-lyon.fr
>>>>>> http://www.creatis.insa-lyon.fr/~amarion
>>>>
>>>> --
>>>> Adrien MARION, Docteur/PhD
>>>> Chercheur post-doctorant (ANR VIP)
>>>> Laboratoire CREATIS, INSA de Lyon
>>>> CNRS UMR 5220, INSERM U1044
>>>> Bâtiment Blaise Pascal, 4ème étage
>>>> 7, avenue Jean Capelle
>>>> 69621 Villeurbanne cedex FRANCE
>>>> Tel : (+33) 4 72 43 87 86
>>>> Fax:  (+33) 4 72 43 85 26
>>>> e-mail : adrien.marion at creatis.insa-lyon.fr
>>>> http://www.creatis.insa-lyon.fr/~amarion
>
> --
> Adrien MARION, Docteur/PhD
> Chercheur post-doctorant (ANR VIP)
> Laboratoire CREATIS, INSA de Lyon
> CNRS UMR 5220, INSERM U1044
> Bâtiment Blaise Pascal, 4ème étage
> 7, avenue Jean Capelle
> 69621 Villeurbanne cedex FRANCE
> Tel : (+33) 4 72 43 87 86
> Fax:  (+33) 4 72 43 85 26
> e-mail : adrien.marion at creatis.insa-lyon.fr
> http://www.creatis.insa-lyon.fr/~amarion
>
>