Application for generating re-accessible screenshots of web pages using histogram shrinkage

We developed an application that can generate a screenshot image of a website and redisplay the website with the URL extracted from the image. Since URLs contain multibyte characters and have variable length, they are converted using Base64 and QR code. The QR code allows error correction. The converted bit sequence is then embedded as a watermark. Unlike natural images, screenshot images are artificial. In many screen-shot images, luminance values tend to be distributed around 0 or 255. When embedding, many watermarks are dropped due to overflow. Therefore, we also propose a method of shrinking the luminance distribution for screenshot images. Compared with the case in which the luminance distribution was left unchanged, the proposed method had a smaller bit error rate and was able to redisplay websites with the URLs extracted from the screenshot images.