A simple enhancement technique for shading in 2D images by retinex model

We propose a simple method to improve human depth sensation for 2D images without depth information. In depth perception of 2D images, a lot of human monocular depth cues are used. Here we focus attention on the shading. And the improvement of depth sensation is achieved by emphasizing it. Based on the idea of painting, shade is expanded and its gradient is made steep. In order to change the pattern of shading, we modulate the reflectance components of images. Retinex model is used for estimation of the reflectance components. These reflectance components are varied to enhance shading and then are reintegrated again with the light images. Through the experiments for CG image and natural image, the effectiveness of our proposed method is illustrated.