How to count no of black spots in a image??

Question

AMIT VERMA 2015-1-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/170508-how-to-count-no-of-black-spots-in-a-image

回答： Image Analyst 2021-6-23

4-1.jpg

clc
A5=imread('C:\Users\AMIT\Desktop\CB\sulphur\4-1.jpg');
imshow(A5);
background = imopen(A5,strel('disk',15));
I2 = A5- background;
figure, imshow(I2)
I3 = imadjust(I2);
figure, imshow(I3);
level = graythresh(I3); %Threshold the Image
bw = im2bw(I3,level);
C = imcrop(bw);
bw2 = bwareaopen(C,2);
figure, imshow(bw2)
cc = bwconncomp(bw2,8) %Identify Objects in the Image
P=cc.NumObjects;
SP=0.64/4;
defectdata = regionprops(cc, 'basic') %Compute Area of Each Object
DA = SP*[defectdata.Area];
[min_area, idx] = min(DA)  %Compute Area-based Statistics
[max_area, idx] = max(DA)
nbins = 20;                     %Create Histogram of the Area
figure, hist(DA,nbins)
title('Histogram of defect Area');
xlabel('Area of defect mm2');
ylabel('Number of defects')
Ylim ([0 50])
DA

4 个评论
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Walter Roberson 2021-6-23

Is the expected answer "3" or is it "lots" ?

Walter Roberson 2021-6-23

imadjust() is only for grayscale images. Your I2 is RGB.

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Answer 1

Image Analyst 2021-6-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/170508-how-to-count-no-of-black-spots-in-a-image#answer_731555

4-1.jpg

You already compute it, in your "P" variable. You probably just didn't notice because of the poor choice of some of your variable names that are not descriptive at all.

See my Image Segmentation Tutorial:

Image Analyst's File Exchange

You might need to define just how small of a spot do you want to find.