Colorizing the Past: Deep Learning for the Automatic Colorization of Historical Aerial Images

J Imaging. 2022 Oct 1;8(10):269. doi: 10.3390/jimaging8100269.

Abstract

The colorization of grayscale images can, nowadays, take advantage of recent progress and the automation of deep-learning techniques. From the media industry to medical or geospatial applications, image colorization is an attractive and investigated image processing practice, and it is also helpful for revitalizing historical photographs. After exploring some of the existing fully automatic learning methods, the article presents a new neural network architecture, Hyper-U-NET, which combines a U-NET-like architecture and HyperConnections to handle the colorization of historical black and white aerial images. The training dataset (about 10,000 colored aerial image patches) and the realized neural network are available on our GitHub page to boost further research investigations in this field.

Keywords: aerial images; deep learning; grayscale image colorization; historical photos.

Grants and funding

This research has been funded by EuroSDR. The authors also acknowledge the Italian National Aerial Photo Library—AFN (in particular Elizabeth Jane Shepherd and Gianluca Cantoro) for kindly providing the historical aerial images used in the reported tests (and partly available in the EuroSDR TIME benchmark—https://time.fbk.eu [accessed on 27 September 2022]).