Help starting opencv project

Here are some suggestions about how you might tackle the problem. First of all you need to decide by which criteria you want to detect a finger in the image. This decision depends mostly on the physical details of your setup. For example:

- The person might wear a thimble that is fluorescent. In a darkend room with ultra violet lighting the finger would be the brightest detail in the image and thereby easy to detect.

- Movement detection: By comparing several images that were taken in a sequence you can detect moving objects in front of a stationary background. After detecting all moving objects you want to analyze the contour of the moving parts for something that has the shape and orientation of a finger.

- In front of a simple homogeneous background you might be able to detect a hand or finger just by color and contrast.

The list of such methods is rather long and they are all more or less complex. Their implementation effort goes from a couple of days to several months or more.

After you have taken that decision it will be quite obvious for you, which functions of OpenCV you would want to use and which other you want to write yourself. If I were you, I would start reading some literature about object detection and general image processing. Things in OpenCV will come naturally to you, once you have acquired the necessary image processing know-how.

I hope that gives you some pointers on where to start.