Is there any way to make sure the circles detected by the imfindcircles function is a solid circle and has no black pixels inside of it?
MATLAB: Finding solid circles using imfind circles
Image Processing Toolboxinfindcirclessolid circle
Related Solutions
A glaring error with your code is this:
P=[blobMeasurements(i).PixelList]; Daurat(P)=0;PixelList is a 2d-array of [columns rows], you then use as a 1d-array to set pixels black. Instead of PixelList, you need to use PixelIdxList which is a 1d-array of pixel indices. So change your regionprops to:
blobMeasurements = regionprops(labeledImage, Daurat, 'Area', 'Centroid', 'Perimeter', 'PixelIdxList');A more important issue is that the test you're doing does not guarantee you a shape close to circle. The r you're calculating is
- for a circle of radius R: r = 2*pi*R/(pi*R^2) = 2/R
- for a square of side 2R: r = 4*2*R/(2R * 2R) = 2/R
- for a thin rectangle of sides a=202R/200 and b = 100*a: r = 2/R
Thus, you can find any shape with a r >0.3.
You would be better off using the Eccentricity property returned by regionprops. An Eccentricity of 0 is a perfect cirle, 1 is a line. Thus I would have:
blobMeasurements = regionprops(labeledImage, Daurat, 'Area', 'Centroid', 'Perimeter', 'PixelIdxList', 'Eccentricity'); for i=1:numberOfBlobs %no need for semicolon. Actually it looks odd.
if blobMeasurements(i).Eccentricity > 0.85 %arbitrary value for you to choose
Daurat(blobMeasurements(i).PixelIdxList) = 0; end endOne final thing:
per(:,1) = [blobMeasurements.Perimeter];is equivalent to:
per = [blobMeasurements.Perimeter]';which looks less odd to me. In any case you don't need it as a column vector so I would just have:
per = [blobMeasurements.Perimeter]; %same for Area
How about comparing length around the blob and length around the bounding box of the blob, like:
% sample blogs
I = imread('pillsetc.png');Iblob = rgb2gray(I) > 200;% measure perimeter and bounding box for each blob
stats = regionprops(Iblob,{'BoundingBox','perimeter'});stats = struct2table(stats);% extract the blob whose perimeter is close to round length of its bounding box
stats.Ratio = 2*sum(stats.BoundingBox(:,3:4),2)./stats.Perimeter;idx = abs(1 - stats.Ratio) < 0.1;stats(~idx,:) = [];% show the result
imshow(Iblob);hold onfor kk = 1:height(stats) rectangle('Position', stats.BoundingBox(kk,:),... 'LineWidth', 3,... 'EdgeColor', 'g',... 'LineStyle', ':');end
Best Answer