[Insight-users] How to sum pixels row-by-row?

Robert Tamburo robert.tamburo at gmail.com
Fri Feb 2 11:48:22 EST 2007


 >> Can you tell me how it is possible to covert images to matrices  
and vice vera?

I'm not sure if there is an ITK class for this, but I imagine that  
you could:
1. Instantiate a vnl matrix that is of the same size as your 2D image.
2. Iterate the image.
3. As the iterator traverses the image, grab the pixel index and value.
4. Set the pixel value in the matrix at the corresponding index.


On Feb 2, 2007, at 11:15 AM, Ali - wrote:

>
> >
> > > It is strange how ITK can perform so many elaborated image  
> processings,
> > > but it takes hours to figure out how to implement some  
> elementary matrix
> > > manipulations. I thought the inclusion of VXL in ITK means  
> having a fast
> > > MATLAB-style image processing toolkit in c++.
> >
> > That's right that many filters are missing to perform simple tasks.
> > ITK is open source, and open to contributions. Feel free to  
> contribute
> > contribute new code to the insight journal :-)
>
> Even if the community provides it, I think it is not a good idea to
> create a 'database' of all operations for images and I have at  
> least 2 reasons for that.
>
> First, it is really hard to find out which class does what  
> operation simply by guessing
> from its name. Secondly, not all the operations can be created as a  
> linear combination
> of the simple operations. This means you have to write filters  
> forever, many of them may be
> used only once.
>
> For example, the slice-by-slice filter you provides does not accept  
> binary filters
> to operate on each slice. So, if I want to divide an N x N image A  
> to a 1 x N image B
> row-by-row, I have to modify the slice-by-slice filter. In the  
> matrix form, this can be
> down simply by 'literally' one line: B->GetTranspose() * A.
>
> Can you tell me how it is possible to covert images to matrices and  
> vice vera? I know ITK
> uses VNL matrices but I cannot see where this is used to  
> maniplulate image pixels directly.
> If this can be done, we won't need hundereds of image operation  
> classes.
>
> >
> > Gaetan
> >
> >
> >
> > --
> > Gaëtan Lehmann
> > Biologie du Développement et de la Reproduction
> > INRA de Jouy-en-Josas (France)
> > tel: +33 1 34 65 29 66 fax: 01 34 65 29 09
> > http://voxel.jouy.inra.fr
>
> Personalize your Live.com homepage with the news, weather, and  
> photos you care about. Try it!
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
> http://www.itk.org/mailman/listinfo/insight-users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://public.kitware.com/pipermail/insight-users/attachments/20070202/14a1f768/attachment.html


More information about the Insight-users mailing list