Shadow removal using Retinex theory

Shadows in images always cause problems to computer visual tasks, so how to remove shadow is an important topic of image processing. In this paper, we propose a new shadow removal method based on Retinex theory. We firstly use the gradient edge detection combined with 1-D illumination invariant image to detect the shadow area, then remove the shadow with Retinex algorithm, finally adjust the brightness of the shadow area. By transforming the RGB image into HSV space, we compute the average brightness of the non-shadow area in original image and shadow-free image, adjust the brightness of the image to coordinate with the original image. The experiment results show that our method can provide a good effect in shadow images.