Hybrid Approach Using Bilateral Filter and Set Theory for Enhancement of Degraded Historical Document Image

Historical documents play vital role in understanding our past. As these documents carry valuable information, preservation of such documents in proper format and state is a major challenge for us. Digitization is the one of the better method to preserve these documents for longer duration. Image processing techniques can be utilized to preprocess the image to enhance the images which are degraded in nature. One of the image processing techniques, preprocessing is the vital step in enhancing the degraded noisy images. In this paper a combination of bilateral filter along with set theory operations are used to enhance the historical document image. The bilateral filter is non linear filter which smoothes the image without smoothing the edges. The proposed method eliminates noise, uneven background and enhances the contrast of the script image. The result of the proposed method is compared with Mean, and Gaussian filter and are better than these methods. Performance of the proposed method is measured using Peak Signal Noise Ratio.