A comparison of color features for visual concept classification

Concept classification is important to access visual information on the level of objects and scene types. So far, intensity-based features have been widely used. To increase discriminative power, color features have been proposed only recently. As many features exist, a structured overview is required of color features in the context of concept classification.
Therefore, this paper studies 1. the invariance properties and 2. the distinctiveness of color features in a structured way. The invariance properties of color features with respect to photometric changes are summarized. The distinctiveness of color features is assessed experimentally using an image and a video benchmark: the PASCAL VOC Challenge 2007 and the Mediamill Challenge.
Because color features cannot be studied independently from the points at which they are extracted, different point sampling strategies based on Harris-Laplace salient points, dense sampling and the spatial pyramid are also studied.
From the experimental results, it can be derived that invariance to light intensity changes and light color changes affects concept classification. The results reveal further that the usefulness of invariance is concept-specific.