how to convert image to binary based on histogram

I need help in converting an image to binary based on histogram. is there a function to do that in matlab? I know there is a function called im2bw(image, thresholdLevel) I could use that but how do I get the level? do I choose something from the histogram?

Thanks

Answer 1

[Image Analyst]

Use graythresh(), or try my thresholding app: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

[Jessica]

I thought so also. thank you for the quick reply :)

Answer 2

[Avishek]

there are several means of automatic thresholding. kmeans, ostu are the most popular if you want to do the thresholding manually

1) plot the histrogram using imhist()

2) find the point in the x-axis of histrogram that seems to divide the histrogram into two parts

if u choose to do it automatically

1) graythresh() gives you ostu thresholding

2)kmeans(), for clustering, this function has various options. you can modify it a bit to get what type of threshold you want.

[Jessica]

thank you :)