High dynamic range (HDR) imaging by gradient domain fusion

This paper proposes a new HDR imaging method in the gradient domain based on the fusion of two images with different exposure. We first formulate an energy function for the binary labeling of each pixel based on the brightness and contrast measure of each image, which gives a binary map that determines whether the under-exposed image is better than the overly exposed one or not. Then a target gradient field is generated by combining the gradient fields of two images according to the binary map. Since the gradient field so combined is generally not integrable, we modify it via Poisson solver. This gradient field is considered that of HDR image and directly compressed to the display scale (in the gradient domain). Experiments show that the gradient domain fusion provides better results than the image domain methods, when fusing two differently exposed images.