Hi Wahlau, I saw your comment but I couldn't answer it before. Thank you for your words to me.
I have another blog and I made some posts about Image Processing and Segmentation (in Portuguese).
If you want to develop anything like the interactive ball, then you should learn about skin segmentation and how to interact the virtual ball with the segmented region.
The simplest algorithm for skin segmentation is the threshold in the channels of color Cb and Cr (in images coded in YCbCr).
The toolbox SIVp has functions for read, write, show, convert, and others operations with images. That toolbox is too simple for install, if you use GNU/Linux, you can install it using the apt-get or synaptic.
PS.: In my other blog, I posted some codes in Scilab for skin segmentation, and anything more.