Are there any comprehensive open-source alternatives to Matlab\'s Image Processing Toolkit?
The best alternative to MATLAB is OpenCV. In fact it is better than MATLAB for real time video and image processing applications. There are lots of resources available online to support it and all u need is basic C programming skills.
Best book is Learning computer vision using OpenCV by gray bradski whose e-book u can easily find.
I have compiled a list of tutorials for beginners on my blog http://8a52labs.wordpress.com/