Correcting Sharpness Variations in Stereo Image Pairs

When stereo images are captured under less than ideal conditions, there may be inconsistencies between the two images in brightness, contrast, blurring, etc. When stereo matching is performed between the images, these variations can greatly reduce the quality of the resulting depth map. In this paper, we propose a method for correcting sharpness variations in stereo image pairs which is performed as a preprocessing step to stereo matching. We modify the more blurred of the two images so that it will match the less blurred image in sharpness as closely as possible. The 2D discrete cosine transform (DCT) of both images is taken, and the DCT coefficients are divided into a number of frequency bands. The signal and noise energy in each band are estimated, and the coefficients are scaled so that the two images have equal signal energy in each band. Experiments show that applying the proposed correction method can greatly improve the disparity map quality when one image in a stereo pair is more blurred than the other.