How to count number of objects in the image, compute their areas, and make probability distribution of the areas?

Hello friends,

I just would like to know how to calculate the objects of image and do the area distribution.

Thanks so much in advance.

Answer 1

[Image Analyst]

In your other question, I saw that you already have a segmented image. So in that case, you can get an area distribution like this

props = regionprops(mask, 'Area');
histogram([props.Area]);
grid on;
title('Histogram of Areas');
xlabel('Area');
ylabel('Count');

[Jialin Men]

Hallo Image Analyst.

Thanks so much.

You are superman. You really teach me a lot

JL

[Image Analyst]

You're welcome. If this Answer solves your original question, then could you please click the "Accept this answer" link to award the answerer with "reputation points" for their efforts in helping you? They'd appreciate it. Thanks in advance. 🙂 Note: you can only accept one answer (so pick the best one) but you can click the "Vote" icon for as many Answers as you want. Voting for an answer will also award reputation points.

[Jialin Men]

Hallo Image Analyst,

I have clicked the Accept this answer.

I have another question.

If I want to know the number of pixels of each particle in this image,

I could also use as below ? right?

props = regionprops(mask, 'PixelValue');

histogram([props.PixelValue]);

[Image Analyst]

No, that's not right. PixelValue is a list of gray levels of all the pixels in each blob. If you want to know the number of pixels in each blob, you need to ask for 'Area':

props = regionprops(mask, 'Area');
allAreas = [props.Area]

You might use bwmorph and use things like the 'bridge' option to break apart barely touching particles. You might also look at watershed. See these links:

Watershed transform question from tech support » Watershed transform question from tech support

Marker-Controlled Watershed Segmentation - MATLAB & Simulink Example

The Watershed Transformation page