A simple question on image processing

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Shamima
Shamima on 10 Apr 2013
Answered: Ayshath Afra on 21 Jun 2020
Hello every body, I have uploaded a simple image on the website:
I would like to extract the outlined portion only. I just startted learning MATLAB. Could any body suggests how I can extract that part of image?
Thanks.
  5 Comments
Walter Roberson
Walter Roberson on 15 Apr 2013
That one does not have any outlined area or any red dashed circle, so I cannot tell what needs to be extracted.
Image Analyst
Image Analyst on 15 Apr 2013
Basically about half way out the blob, there is a thin, faint, noisy, interrupted "ring" of dark pixels. That is what she wants to find.

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Answers (3)

Image Analyst
Image Analyst on 10 Apr 2013
What do you mean by "extract"? Do you mean you want an image with everything outside the circle blackened? Do you want the bounding box of it cropped out to another, smaller image? Do you just want a list of all pixels inside the circle in a 1D list?
  15 Comments
Shamima
Shamima on 15 Apr 2013
I need to see how to use these functions in MATLAB. At this moment, I have displayed the images using C program and I found for a certain arc length, along the indent/ notch the pixel value is very high. For a small portion of arc length, I find this property in all images after thresholding. Now from that small piece of arc lenth, i need to find correct center by varying the angle for particular arc length. If you any good algorithm about this, please let me know. I am not sure whether I am proceeding on the right track. As I am not familiar with MATLAB, I find difficulty in using the MATLAB functions.
Cedric
Cedric on 15 Apr 2013
Edited: Cedric on 15 Apr 2013
>> As I am not familiar with MATLAB, I find difficulty in using the MATLAB functions.
At this point, I would recommend the official documentation available here. If you are already familiar with another language, you would spend probably no more than a long day full time, which would prevent you from being constantly pulled back by lack of knowledge about MATLAB basics (which are not trivial, especially if you have a challenging application to develop). I would recommend the following actually:
Under MATLAB, you could get..
  • PDF labeled "MATLAB Primer" and study chapters 2 and 5.
  • PDF labeled "Mathematics", and train to have a good mastery of chapters 1 and 9.
  • PDF labeled "Programming Fundamentals" and have a look at the table of content so you can use it as a reference later.
There would also be the User's Guide under Image Processing Toolbox, which contains a significant amount of examples and illustrations.

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Shamima
Shamima on 10 Apr 2013
Yes, I would like to remove every thing outside the outlined boundary. I only need the portion that lies inside the boundary. Thanks.
  4 Comments
Image Analyst
Image Analyst on 10 Apr 2013
See the comment in my answer above.
Shamima
Shamima on 10 Apr 2013
Hi, thanks for the comments. There won't be any red pixel boundary, I have put the original image to the following link:
https://docs.google.com/file/d/0BwwPVFIzkQWSYTU4OVNqN24zdE0/edit?usp=sharing
I need to crop out a portion as shown with some indentation mark in the original image. How can I crop up that portion. Thanks.

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Ayshath Afra
Ayshath Afra on 21 Jun 2020
% create pre-processed datastore
imdb = imageDatastore(db_path,...
'IncludeSubfolders',true,...
'LabelSource','foldernames',...
'ReadFcn',@readCBIR);
Does anything wrong in this command

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