We present a generic objectness measure, quantifying how
likely it is for an image window to contain an object of
any class. We explicitly train it to distinguish objects with
a well-defined boundary in space, such as cows and telephones,
from amorphous background elements, such as
grass and road. The measure combines in a Bayesian
framework several image cues measuring characteristics of
objects, such as appearing different from their surroundings
and having a closed boundary. This includes an innovative
cue measuring the closed boundary characteristic. In experiments
on the challenging PASCAL VOC 07 dataset, we
show this new cue to outperform a state-of-the-art saliency
measure [17], and the combined measure to perform better
than any cue alone. Finally, we show how to sample
windows from an image according to their objectness distribution
and give an algorithm to employ them as location
priors for modern class-specific object detectors. In experiments
on PASCAL VOC ...