[Insight-users] Binary Image segmentation

Luis Ibanez luis.ibanez at kitware.com
Tue Aug 14 12:15:52 EDT 2007 

Hi Gopal,

Thanks for posting your images.

They are quite interesting.

ITK can provide you the low level "feature detection" functionalities that
you need here. For example : line,  corner, crossing detection.

All based on analyzing the parametric space of the Hessian image.

We just run a quick test with the application:

    /InsightApplications/Curves2DExtractor/Curves2DExtractor

By loading as input image:

          Output_Bottom_Left.JPG

Setting the Sigma value ( for the Hessian) to 0.8 and
using the following parameters in the "Spatial Function" panel:

Angle Z = 34.5
Aperture X = 18.8
Aperture Y = 3
Apex Coordinates
X= 0.3
Y = 0
Z = 1
Top Plane = 0.05
Bottom Plane = 2

We put a screen shot of the results at:

   http://public.kitware.com/pub/itk/UsersITK/Curve2DExtractor/


The results indicate that you should be able to extract many
of the features, *BUT* you will need higher resolution images.
(Maybe 5 to 10 times higher that what you sent. This need for
higher resolution is related to the use of Second derivative
operators in the Hessian.


When you click on the button : "Parametric Space"

You will see appearing a scatter plot of the pixel values
in the parametric space. Different features (lines, corners, crossings)
are located in different places of this parametric space. For example,
Lines are located along in the plane Y=0, along the spine of a line
that goes from the apex of the truncated pyramid to a middle point
in the X axis.


You will have to work out different spatial functions to capture the points
corresponding to every particular feature.


    Please let us know if you have further questions,


       Thanks


           Luis



-------------------------------------------------------------------------
On 8/5/07, gkaremore at scai.fraunhofer.de <gkaremore at scai.fraunhofer.de>
wrote:
>
> Hi Luis
>
> Thanks for your comments. Please check this link :
>
> http://www.gopalrk.com/forITKCommunity.html
>
>
> If this link doesn´t work. Please check following.
>
>
> Input Image : http://www.gopalrk.com/Input_Image.jpg
>
> Output Image 1: http://www.gopalrk.com/Output_left_top.jpg
>
> Output Image 2: http://www.gopalrk.com/output_Rt_Top.jpg
>
> Output Image 3: http://www.gopalrk.com/Output_Bottom_Left.JPG
>
> Please me know your comments, I will surely go through the approach we
> discussed in previous email.
>
> Thanks!
>
>
> Sincerely
> Gopal
>
>
>
>
> Luis Ibanez wrote:
> >
> > Hi Gopal,
> >
> >
> >      Thanks for better describing your problem.
> >
> >
> > In your case, it seems that  what you are segmenting
> > (rather classifying) are the symbols in the document.
> >
> > Is that right  ?
> >
> > It will still help a lot if you post somewhere a representative
> > image of your problem.
> >
> >
> >
> > Before getting to a classification stage you will need to
> > define appropriate *descriptors* that capture the uniqueness
> > of each one of the symbols.
> >
> >
> > Funny enough, you the first step is to start by considering
> > your "binary" image as a grayscale images, and apply for
> > example a Hessian image filter.
> >
> > Then pass the output of  Hessian filter to the EigenAnalysis
> > filter and obtain the eigen vectors and eigen values at
> > every pixel in your image.
> >
> > If your image is composed of letters, then you will be able
> > to "detect" the linear part of the letters as "ridges"
> > in intensity.
> >
> > You will also be able to detect the crossings between lines
> > as regions where the two eigen values are similar.
> >
> > Look for example at:
> >
> >      http://www.itk.org/HTML/Curve2DExtraction.htm
> >
> > You will find the code of this application in the
> > InsightApplications checkout.
> >
> > Note that this applications is only looking for ridges,
> > and therefore uses a pattern recognition approach that
> > is very specific to ridges.
> >
> > You may want to extend it in order to capture also
> > corners, crossings.... etc.
> >
> >
> > Do you already have a way of defining regions of interest
> > around letters ? words ? in the document. If not, you should
> > explore a method for it.
> >
> > Given a region of interest, and having detected particular
> > features of the letter traits (ridges, corners, crossings,
> > ends), you could use the combination of features in order
> > to distinguish some letters from others.
> >
> > for example the letter "O" doesn't have crossings, ends,
> > or corners), while the letter "A" has two crossings, two
> > ends, one corner, and 5 segments that look like ridges.
> >
> >
> > Note that code for analyzing vasculature has a lot in common
> > with the problems that you will face when performing text
> > recognition.
> >
> >
> > Please give it a try at the Curve2DExtractor application,
> > and let us know how it goes for you.
> >
> >
> >     Regards,
> >
> >
> >        Luis
> >
> >
> > -------------------------------------
> > gkaremore at scai.fraunhofer.de wrote:
> >> Hello Dan
> >>
> >> Thanks for your effort in understanding the problem. I meant by word
> >> segmenting is not with respect to medical(or other)image processing, my
>
> >> application is Document image segmentation. In another words , It would
> >> be
> >> called as multiclass labeling problem. Please see following papers
> >> related
> >> to binary image segmentation.
> >>
> >> Bayesian decision feedback for segmentation of binary images
> >> Kadaba, S.R.; Gelfand, S.B.; Kashyap, R.L. Acoustics, Speech, and
> Signal
> >> Processing, 1995. ICASSP-95., 1995 International Conference on
> >> Volume 4, Issue , 9-12 May 1995 Page(s):2543 - 2546 vol.4
> >>
> >> Strzelecki M., Segmentation of Binary Images Using Network of
> >> Oscillators,
> >> 2 Krajowa, Konferencja Komputerowe Systemy Rozpoznawania KOSYR 2001,
> >> 28-31
> >> May 2001
> >>
> >> Especially papers from "International Journal of Document Analysis and
> >> Recognition (IJDAR) - Computer Imaging, Vision, PR and Graphics "
> >>
> >> My criterion to cluster is Shape:
> >>
> >> I want rectangular,square, and horz and verticle line component to be
> >> labbled in separation to Text and graphics on the document(Under
> >> segmentation/clustering/labeling).
> >>
> >> currently I am trying with "Feature extraction" section of ITK toolbox.
> >> Results are not appreciable. So looking for a different approach using
> >> ITK
> >> library.
> >>
> >> Thanks in advance.
> >>
> >> Sincerely
> >> Gopal
> >>
> >>
> >> Dan Homerick wrote:
> >>
> >>>Hi Gopal,
> >>>
> >>>I'm not sure if I understand what you mean by segmenting a binary
> image.
> >>>"Segmentation" is typically reducing a grayscale or color image so that
> >>>only
> >>>a few values are used, done in such a way that each color in the
> >>> resulting
> >>>image has some semantic meaning. If you're starting with a binary
> image,
> >>>there's not much segmentation that can be done.
> >>>
> >>>It sounds like what you really want is to cluster (unconnected)
> >>> components
> >>>of your binary image into logical objects. By what criteria do you want
> >>> to
> >>>cluster them (spatial proximity, similarity of size, shape, other)? I
> >>>don't
> >>>think there will be a simple filter to accomplish that, but if you can
> >>>provide more details of what you intend to do, the mailing-list may be
> >>>able
> >>>to provide some guidance.
> >>>
> >>>Cheers,
> >>> - Dan
> >>>
> >>>On 8/2/07, gkaremore at scai.fraunhofer.de <gkaremore at scai.fraunhofer.de>
> >>>wrote:
> >>>
> >>>>Dear All
> >>>>
> >>>>Does ITK help in segmenting binary images. In another words ITK
> >>>>segmentation library provides function to segment only gray scale and
> >>>>color image. Will ITK helpfull in segmenting binary images in  to
> >>>>different clusters. (Tried Binary threshold filter, connected
> component
> >>>>algorithms).
> >>>>
> >>>>Is there any other method by which we can segment binary image in ITK.
> >>>>
> >>>>Any comments would be appreciable.
> >>>>
> >>>>Sincerely
> >>>>Gopal
> >>>>
> >>>>Research Scholar
> >>>>Fraunhofer Institute
> >>>>Germany
> >>>>_______________________________________________
> >>>>Insight-users mailing list
> >>>>Insight-users at itk.org
> >>>>http://www.itk.org/mailman/listinfo/insight-users
> >>>>
> >>>
> >>
> >> _______________________________________________
> >> Insight-users mailing list
> >> Insight-users at itk.org
> >> http://www.itk.org/mailman/listinfo/insight-users
> >>
> >
>
> _______________________________________________
> Insight-users mailing list
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