Augment color discrimination of local descriptors

Scale invariance and color invariance are two critical characters of robust local descriptors. For scale invariance, most of local descriptors are constructed based on scale pyramid only, while lack of considering the resolution influence. For color invariance, most of local descriptors are constructed by joining the color features to gray features. This enhances color discrimination of local descriptors but doubles descriptors' length. In this paper, we analyze the resolution influence for descriptor robustness and give a way to construct the base layer of scale pyramid by resolution analysis. And then we propose a color transformation method to extract robust color discriminated local descriptors. At last, we validate the proposed method on different color and resolution image sets.