How do I darken a certain part of the image?

Hello

I wanna do darken circle's around .Circle and its inside must stay like the way it is.How can i do that with simple way?Firstly i think about the nested for loops. i and j (row and cloumns) pixel values must be 1 or 0 respectively.Is this idea true?Can someone give me an advice for this?

[Stephen23]

@Özge Akbülbül: I uploaded your image to this forum. Third-party websites are not very reliable as they easily disappear or the links break which makes your question meaningless in future. Also some regular contributors here won't download from any third-party sites.

[Rik]

Unfortunately, the image Stephen added seems to be missing from the Google cache, but the rest of the question is still there:

How do I darken a certain part of the image?

Hello

I wanna do darken circle's around .Circle and its inside must stay like the way it is.How can i do that with simple way?Firstly i think about the nested for loops. i and j (row and cloumns) pixel values must be 1 or 0 respectively.Is this idea true?Can someone give me an advice for this?

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Akira Agata]

One possible solution would be like this:

% Read the file and convert to gray-scale image
I = imread('b.jpg');
Igray = rgb2gray(I);

% Extract the circle by selecting the region with maximum bounding box
BW = imbinarize(Igray);
s = regionprops('table',~BW,'BoundingBox','PixelIdxList');
[~,idx] = max(s.BoundingBox(:,3).*s.BoundingBox(:,4));

% Make the mask image by filling the circle with 'true'
BWmask = false(size(BW));
BWmask(s.PixelIdxList{idx}) = true;
BWmask = imfill(BWmask,'holes');

% Mask the image
Iresult = Igray;
Iresult(~BWmask) = 0;

% Show the reusult
imshowpair(Igray,Iresult,'montage')