Split and Merge image segmentation algorithm in OpenCV
I asked Google again for you, but I did manage to find some hits in the end. There is already a very good question on stackoverflow concerning the exact same thing you are interested in.

There is a very nice explanation of split-and-merge provided in one of the answers, as well as simplified pseudocode.

The other answer provides a link to the implementation (although I did not check it, I'm not sure which language the implementation is in).

If you want to use split-and-merge as a reference segmentation technique to compare your idea with, other segmentation methods offered by OpenCV might also be interesting:


functions useful in image segmentation from the OpenCV manual
a chapter dealing with image segmentation in OpenCV from Gary Bradski; Adrian Kaehler: Learning OpenCV
article about Pyramid segmentation
Mean-shift segmentation: stackoverflow answer, scientific article
Watershed segmentation seems fairly well explained by Wikipedia


In the end, you can choose one of the already offered methods as the reference method after all, or, if you want to present amazing, all-encompassing comparisson, you might also want to use more than one reference method