Two Decades of Colorization and Decolorization for Images and Videos

TL;DR

This paper reviews twenty years of research on colorization and decolorization techniques for images and videos, highlighting progress, challenges, and applications in enhancing and converting visual media.

Contribution

It provides a comprehensive overview of the development and advancements in colorization and decolorization methods over the past two decades.

Findings

Significant progress in algorithms balancing spatial-temporal consistency.

Increased application in digital media enhancement and restoration.

Ongoing challenges in achieving real-time processing and high quality.

Abstract

Colorization is a computer-aided process, which aims to give color to a gray image or video. It can be used to enhance black-and-white images, including black-and-white photos, old-fashioned films, and scientific imaging results. On the contrary, decolorization is to convert a color image or video into a grayscale one. A grayscale image or video refers to an image or video with only brightness information without color information. It is the basis of some downstream image processing applications such as pattern recognition, image segmentation, and image enhancement. Different from image decolorization, video decolorization should not only consider the image contrast preservation in each video frame, but also respect the temporal and spatial consistency between video frames. Researchers were devoted to develop decolorization methods by balancing spatial-temporal consistency and algorithm efficiency. With the prevalance of the digital cameras and mobile phones, image and video colorization and decolorization have been paid more and more attention by researchers. This paper gives an overview of the progress of image and video colorization and decolorization methods in the last two decades.