Historical document image enhancement using background light intensity normalization

This work presents a background light intensity normalization algorithm suitable for historical document images. The algorithm uses an adaptive linear function to approximate the uneven background due to the uneven surface of the document paper, aged color and light source of the cameras for image lifting. Our algorithm adaptively captures the background with a "best fit" linear function and normalized with respect to the approximation. The technique works for both gray scale and color images with significant improvement in readability.