Comparative study of strategies for illumination-invariant texture representations
Barbara V. Levienaise-Obadia, Josef Kittler, William J. Christmas · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1998
Illumination invariance is of paramount importance to annotate video sequences, stored in large video databases. However, popular texture analysis methods, such as multichannel filtering techniques, do not yield illumination-invariant texture representations. In this paper, we assess the effectiveness of three illumination normalization schemes for texture representations, derived from Gabor filter outputs. The schemes aim at overcoming intensity scaling effects, due to changes in illuminating conditions. A theoretical analysis and experimental results, enable us to select one scheme as the most promising. In this scheme, a normalizing factor is derived at each pixel, by combining the energy response of different filters at that pixel. The scheme overcomes illumination variations well, while still preserving discriminatory textural information. Further statistical analysis may shed light on other interesting properties or limitations of the scheme.