No reference uneven illumination assessment for dermoscopy images

For the dermoscopy image, uneven illumination will influence segmentation accuracy and lead to wrong aided diagnosis result. In this paper, a no reference uneven illumination assessment metric is proposed for dermoscopy images. Firstly, the distorted image is decomposed to illumination and reflectance components through variational framework for Retinex (VFR). Then, the illumination component is extracted by basis function fitting. Lastly, average gradient of the illumination component (AGIC) is calculated as the uneven illumination metric. A series of experiments show that, the proposed illumination extraction method is insensitive to the image content, and the proposed metric delivers an accurate illumination assessment result.