Contrast Enhancement in Direct-Projected Augmented Reality

In direct-projected augmented reality, use of projector makes it possible to utilize 3-D real and large objects as displays and frees from discomforts incidental to wearing a device such as HMD. However, the resulting augmentation usually has poor depth resolution due to projectors with low contrast. In direct-projected augmented reality, the radiometric compensation, which is originally employed to recover the color properties of the projector input image in direct-projected augmented reality, seems to be another cause of decreasing the final contrast of the augmentation. In this paper, a contrast enhancement method is proposed that combines a hue- and saturation- preserving histogram equalization with the radiometric compensation in direct-projected augmented reality. The method guarantees that the radiometrically compensated color is maintained while the brightness (or intensity) contrast is enhanced. Experimental results demonstrate the validity of our method.