[vtkusers] Combination of two images

[David Gobbi]

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
>