Extracting Hollow circles from Phase Contrast Images (image analyst )

Hello, I am an undergrad student at the University of Central Florida working with Phase Contrast images that I obtained by experiment at Argonne’s National Labs Advanced Photon Source. I have been working with these images for the past three months and have reached a wall. I have written hundreds of lines of code in MATLAB, utilizing every package and have worked extensively with ImageJ (Fiji) but with little improvement.

My Problem:

I need to isolate the small particles in this image. (Find them, isolate them, and fill them (white circles)).They are hollow circles that are very similar to the Background. They are difficult to see in a static frame so I have attached a gif.

Image(hard to see anything):

Close up:

Some of them circled :

GIF (make it full screen to see)

The images are 16bit tiffs. 1024x1024

My current approach is two subtract the next image from the current image, and then multiply it by a factor of 10-100.

Image=(image(K)-image(k+1))*10

Result:

I am then using a circle algorithm to find the circles and fill them in for I can track them.

Even through I spent a lot of time developing this, I am not to happy with it. Primarily since the images are subtracted images (ghost particles) and the circle finder has inconsistencies between frames.

I would prefer to alter the original images and exact the circle features, but I can figure out how. Can someone please help?!

I recently discovered that the circle finder can “kinda” find the circles in the orginal images (i.e. the white circles in the second image) but I am unsure of the error over an entire image.

Here is a link to a google folder with 10 images:

https://drive.google.com/drive/folders/1botW2ehlTKcj_50zNWs_aM7Ia5-B7Mho?usp=sharing 1

Note: I have tried all types of edge detection/blob detections, wake segmentation and a lot of others but I must be missing something.