Block-based illumination-invariant representation for color images

Reflection effects such as shading, gloss, and highlight affect the appearance of color images greatly. Therefore, image representations invariant to these effects were proposed for color images. Most of the conventional invariant methods used the dichromatic reflection model assuming the presence of dielectric material in the captured image. Recently, a pixel-based invariant representation for color images, assuming that the image includes dielectric materials and metals, was introduced. However, the pixel-based representation was noisy and did not have sharp edges. This paper proposes a block-based illumination-invariant representation for color images including dielectric materials and metals. The proposed algorithm divides image into sub-blocks and applies the invariant equations within each block. Experiments show that the proposed algorithm has clear and sharp edges over the pixel-based algorithm. The results show the performance and stability of the proposed algorithm. As an application, the proposed invariant method is applied to color image segmentation problem. Keywords: Invariant representation, Dichromatic reflection model, Color image segmentatio