how do i analyze the objects properties (size, diameter...) in an image?

i need to measure the grain dimensions from this image:

this is an image of a steel taken by microscope. i want to measure the grains (the black areas). Do anyone knows if there are existing apps or code that I can use for that purpose?

Answer 1

[Image Analyst]

See my Image Segmentation Tutorial in my File Exchange http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862. You might also want to check out the color segmentation demos there.

[eran golden]

hi, I tried to use the blobsDemo by opening it's code and swiching the "coins.bmp" pic to mine (the one in my question, jpg format). it doesn't work... what do I need to change in the code in order to get the grain sizes?

[Image Analyst]

Upload your image here so I can try it. Also, did you read the comments? There are instructions in it for places where you might need to make changes, such as changing the thresholding if you want dark objects instead of light objects, etc.

[eran golden]

I want to know 2 things from this pic: 1. the area of each grain or the average area of the grains 2. the percentage of each color

[Image Analyst]

You need to get the binary image first. I told you how to do that in your duplicate question. Since we should not carry out this discussion in multiple threads, let's continue it there.