  Translating face sketches to photo-realistic faces is an interesting and
essential task in many applications like law enforcement and the digital
entertainment industry. One of the most important challenges of this task is
the inherent differences between the sketch and the real image such as the lack
of color and details of the skin tissue in the sketch. With the advent of
adversarial generative models, an increasing number of methods have been
proposed for sketch-to-image synthesis. However, these models still suffer from
limitations such as the large number of paired data required for training, the
low resolution of the produced images, or the unrealistic appearance of the
generated images. In this paper, we propose a method for converting an input
facial sketch to a colorful photo without the need for any paired dataset. To
do so, we use a pre-trained face photo generating model to synthesize
high-quality natural face photos and employ an optimization procedure to keep
high-fidelity to the input sketch. We train a network to map the facial
features extracted from the input sketch to a vector in the latent space of the
face generating model. Also, we study different optimization criteria and
compare the results of the proposed model with those of the state-of-the-art
models quantitatively and qualitatively. The proposed model achieved 0.655 in
the SSIM index and 97.59% rank-1 face recognition rate with higher quality of
the produced images.
