An extensive survey on traditional and deep learning-based face sketch synthesis models

In recent days, Face sketch synthesis (FSS) attracts various researchers for sketching the images to retrieve faces and in multimedia applications. The intention of FSS is to create a sketch for the image provided from a collection of sketch and photo images as the training set. Presently, the rise of deep learning (DL) models becomes useful in FSS because of its diverse benefits. As the FSS is employed in various applications, detailed experimentation to analyze the state of the art approaches methods is nontrivial. Though numerous FSS approaches are available, there is no review paper exist regarding the hierarchical classification of DL based FSS. Keeping this in mind, in this paper, we provide an extensive review of the available DL as well as conventional FSS techniques. We made a clear classification of the FSS techniques, and these are categorized into data-driven and model-driven methods. A comparative analysis of the reviewed techniques is made based on various aspects such as the objective, algorithms used, benefits, and performance measures.