Detecting Water Droplets

I need to detect water droplets on different surfaces. I have a picture of the original surface, but the lighting is slightly flickery so the shadows change slightly. I have tried many variations of tracing edges and circle detection. I have also increased the image contrast and equalized the brightness of the image by using histeq() in various combinations before using any of the previously mentioned methods.

Here is an example of my images. The first picture is before any condensation, and the second has the droplets I want to analize/isolate. http://imageshack.us/g/685/a00120110714092419.png/

Answer 1

[Image Analyst]

Maybe try this: http://blogs.mathworks.com/pick/2008/05/23/detecting-circles-in-an-image/

If you can change the water to quinine water you can use UV fluorescence photography, because the water will glow. Just another example of how improving or changing the image capture situation will give you an image that is easier to measure.

[Julie]

I can't add anything to the water, I am looking at condensation from the humidity in the air. Also as for improving the image capture sitation I have tried everyhing I can think of, including diffusing my light source so the flickering is dimished and the pictures posted are the result.

Also, I have already tried the program the tutorial sugests as well as many of the other teqniques sugeated, I can't seem to get it to pick up the droplets correcttly. But thank you for the sugestions.

[Doug Eastman]

How flat is the surface? Perhaps you could scan a laser just about the surface to highlight the drops better?

[Julie]

No, It it in a really small chamber, and I need to take the data over time. Also, I don't have that much freedom over the setup.

Answer 2

[Sean de Wolski]

perhaps an

imdivide %?

[Julie]

Would that work if the shadows were diffrent lengths/sizes? Because I tried imsubtract as well as imabsdiff and neither of those worked.

[Sean de Wolski]

A division is probably better for illumination issues.

[Julie]

I tried using imdivide(), but all I get is a completely black screen. Am I doing something wrong?