We propose an efficient method, built on the popular Bag
of Features approach, that obtains robust multiclass pixellevel
object segmentation of an image in less than 500ms,
with results comparable or better than most state of the art
methods. We introduce the Integral Linear Classifier (ILC),
that can readily obtain the classification score for any image
sub-window with only 6 additions and 1 product by
fusing the accumulation and classification steps in a single
operation. In order to design a method as efficient as
possible, our building blocks are carefully selected from the
quickest in the state of the art. More precisely, we evaluate
the performance of three popular local descriptors, that
can be very efficiently computed using integral images, and
two fast quantization methods: the Hierarchical K-Means,
and the Extremely Randomized Forest. Finally, we explore
the utility of adding spatial bins to the Bag of Features histograms
and that of cascade classifiers to im...