Huang et al. introduce a new superpixel algorithm that uses spatial and color quantization to very very efficient – called USEQ. Their approach can easily be summarized in four steps: first, a spatial quantization is computed (essentially a regular grid); second, a color quantization is computed (see paper for details), third, each pixel is – individually – assigned to a label through MAP estimation where the probability of belonging to a specific superpixel is derived from the corresponding quantizations; lastly, a post-processing step merges small superpixels.
In experiments, the authors show that the proposed method is significantly faster than many other algorithms. Still, the qualitative results, Figure 1, look convincing.