In this notebook I will present a step-by-step approach that uses deep learning techniques for colorizing grayscale images. By utilizing a pre-train image from Kaggle, we are able to change into CIELAB color space. Then we propose a method to add color into grayscale image using model that we build using Tensorflow. As an application, we colorize the portrait of historical image and obtain interesting result, showing the potential of this method in the growing field of computer-assisted art.