ffmpeg is a powerful tool for all kinds of stuff to do with videos.
It is pretty easy to convert a sequence of images into a video:
ffmpeg -sameq -f image2 -i test%03d.png video.avi
This will take an image sequence from the files test001.png, test002.png, …, test010.png, … and convert it into the video video.avi.
%03d is a format string which defines that the number is filled up with zeros to have at least three digits. You can change it according to the naming schema of your input files.
-sameq tells ffmpeg to use the same quality for output as it found in input. For the image sequence this gives you nearly no loss of quality, but it also results in a really big video.
You see, it is really easy to convert images into video with ffmpeg!