Hello,
I have experience in working with computer vision and image processing applications.
I am not 100% sure if the same code would work on OSX and Win, but I have built an app for kinect with OpenFrameworks and it worked on both., so I am pretty positive it is achievable.
I am not a big fan of multiplatform solutions (e.g. iOS - Android), but openFrameworks has not failed me yet.
OpenFrameworks is a C++ library.
Another option would be probably Processing or just plain JAVA.
I would be very happy to work with you,
Matus Vojcik