In this paper, we present a superresolution-based text enhancement scheme to improve optical character recognition (OCR) and readability of text in digital video. The quality of videotext is degraded by factors such as low resolution, antialiasing, clutter and blurring. We use the fact that the same text string often exists in consecutive frames to explore the temporal information and enhance the text image. For graphic text, we register text blocks to subpixel accuracy and fuse them to a new block with high resolution and a cleaner background. We use a projection onto convex sets (POCS) based method to de-blur scene text to improve readability. Experimental results show our scheme can improve OCR for graphic text and readability for scene text significantly.