Extraction of the region of interest in MATLAB

I have this binary image as my input and I want to extract the region marked in red automatically without manually providing any coordinates Any help will be appreciated

[KSSV]

Attach the original image.....what is the logic behind selecting it? Is that you have black region within white region?

[anshumala rakesh]

Actually I was given a gray-scale image in .TIF format and I had to extract this A type region.so I binarized it and since it was the largest area so I extracted it using the bwareafilt but now I have to extract that particular region

[anshumala rakesh]

This is the original image which I have converted in .BMP for uploading purpose

Answer 1

[JSC]

Here is some code which should work for this task:

Read in the image:

   Image=imread('input.bmp');
    figure
    imshow(Image)
Get the red and green channel of the rgb-image:

RedChannel=Image(:,:,1);
GreenChannel=Image(:,:,2);

Convert red areas to 1 and others to 0:

Image_BW = (RedChannel>200).* (GreenChannel<100);
figure(1)
clf
imshow(Image_BW)

Get the boundaries:

B=bwboundaries(Image_BW);

Get and plot inner boundary

Bound=B{2};
hold on
plot(Bound(:,2),Bound(:,1),'g-')

Get minimal and maximal x-position of roi

min_x=min(Bound(:,2));
max_x=max(Bound(:,2));
Image2=zeros(size(Image));

%loop over columns intersecting roi

for i=min_x:max_x

    %get logical vector with 1s for roi-boundary-pixels in ith line
    x=Bound(:,2)==i; 

    %get minimal and maximal y-value of roi in ith column
    min_y=min(Bound(x,1));
    max_y=max(Bound(x,1));

    %write ith column of roi to Image2
    Image2(min_y:max_y,i,:)=Image(min_y:max_y,i,:);
end

Plot the result

figure(2)
imshow(Image2);

[anshumala rakesh]

Thank you so much for answering I appreciate your help but IAM not getting the desired result:(

[JSC]

So did you imagine something different or is the code not working on your machine?

[anshumala rakesh]

Actually the input image is a gray-scale image in .TIF format . Sorry as I wasn't able to upload that so I converted into .BMP format Sorry for the inconvenience caused.can you help me now

[JSC]

So is the answer what you imagined? Can you run the code for the bmp-image?

[anshumala rakesh]

No not properly