Hi William,

I first of all wanted to thank you for your PIVLab Toolbox; it is really great! Thanks! For one of my projects, I am trying to determine the flow inside vibrating small droplets.

Since I have an oscillating droplet, having the same mask for all images is not a solution for me and since I have a lot of images to process, drawing the masks by hand one by one is just impossible... I have been able to compute the polygon for each frame, as shown in the example enclosed, but I found myself stuck. I have two distinct problems:

1) The polygon computed will mask the interior of the droplet and not the exterior, which is actually my ROI...;

2) Since the droplets change in size, the vectors xmask and ymask also change in size, so I have to work with cells (xmask and ymask have to be cells not vectors - at least I haven't found another solution), but this doesn’t work with PIVLab --> I can load a unique mask fine, but not different masks for each frame...;

Maybe it is possible to subtract two masks - the whole image minus the droplet-mask - but I don’t know how to do that…

For now, I have find an “okay" solution by multiplying the original image by the mask. But I do get some issues at the boundary of the droplet.

Thanks a lot for your reply,

Antoine