# Color Harmonization, Deharmonization and Balancing in Augmented Reality
## 2 Related Work
### Recoloring Techniques for Augmented Reality Content  
Past approaches provide undeniably accurate results, though they are just focused on static images and videos. In this regard, other solutions were proposed to extend the recoloring process to the AR with aim to improve the quality of the integration of virtual objects in the real environment.  
[PERSON] et al. [56] proposed a solution for harmonizing the combinations of colors of both real and virtual objects in an AR-based scenario. Authors introduced the concept of constrained color harmonization by identifying different types of color-to-object assignments. The downside is that this solution allows for harmonizing colors following only the approach proposed in previous works. In [57; 58], researchers investigated what adaptations can be chosen to improve the legibility of graphical symbols superimposed on real-world images by proposing four different types of adaptation by varying several parameters (including thickness and color luminosity of the border, size of symbols, color of the letters or digits inside symbols). Results showed how to combine types of adaptation to improve symbol salience.  
In spite of this, there are no experiments to prove the effectiveness of their solution for an augmented visualization. [PERSON] et al. [13] addressed the issue of selecting the appropriate colors to be assigned to monsters in the ARQuake game by proposing a mobile AR application. The experiments were conducted considering nine colors with four intensities in different scenarios. Although the results confirm the existence of an appropriate set of colors depending on the conditions, the choice is still limited to a few colors.  
[PERSON] et al. [59] proposed a mobile AR application for a museum context. The application allows visitors to change the colors of a reconstructed virtual painting on the basis of the real one in an interactive way. A user can therefore produce a personal and recolored version of the painting. The recoloring starts from the generation of layers by means of an automatic soft color segmentation algorithm that significantly reduces the manual labor required by the user. Various results are presented by the authors that confirm the usefulness of the proposed solution. Nevertheless, this work has a different target from ours.  
[PERSON] et al. [60] presented an AR application to view pieces of furniture in different colors and styles within the real scenario to enhance user experience. Their approach exploits functionalities of deep-learning based on semantic segmentation and fast-speed color transformation to recognize and segment furniture in the users' field of view, and to overlap a virtual color layer on top of them. Furthermore, the application runs on a head-mounted AR headset device. Unfortunately, selected colors are not harmonized with the ones contained in the real background. In this context, a set of novel methods to automatically recolor augmented reality content according to colors of the background is proposed. Three different approaches are presented for satisfying different needs in different settings, aiming to improve the quality of the AR visualization.