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Top1. Introduction
Today, one deals with digital images on a daily basis. Digital images play an important role in daily life applications such as biomedical imaging, satellite imaging, multimedia imaging system and R&D imaging. Digital image processing enables one to extract the pictorial details and useful information from a given low quality image. The field of image processing has grown considerably during the last few decades, with the developments in digital computer technology in terms of improvement in size, speed and cost effectiveness. Today, the technology has reached such a level that one can purchase a compact image processing system off the shelf to capture and manipulate an image the way one wants.
To study the digital image processing the whole process may be divided into number of stages out of which image restoration concerns the removal or reduction of degradations which have occurred during the acquisition of the image. Advances of technology made possible the transition from traditional manual retouching methods to digital techniques. Digital image inpainting is an important issue in the domain of image restoration and an international interesting research topic in recent years, and it has different terminology names in different areas. For example, it is called error concealment in the signal transmission, and is called art inpainting etc. Digital inpainting is one of the techniques of filling in the missing regions of an image using information from surrounding area. The term digital in painting was introduced by Bertalmio (Bertalmio et al., 2000) in the year 2000. In the parlance of digital inpainting, the missing region is often referred to as hole and is usually provided by the user in the form of mask or can be obtained by applying different techniques. Digital inpainting has found wide spread use in many applications such as retrieval of damaged old paintings and photographs, removal of undesired objects and writings on photographs, transmission error recovery in images, computer-assisted multimedia editing and replacing large regions in an image for privacy protection. The goal of the inpainting technique is to modify the damaged region in an image in such a way that the inpainted region is undetectable to a neutral observer. Alternately, the objective of inpainting is to reconstruct the missing or damaged portions of the work, in order to make it more legible and restore its unity.
Early artistic creation could not have survived over the years if it was not for the image and art restoration artists that brought old or damaged paintings back to the original or a close-to-the-original state. Artwork dating back to the Middle Ages was already in need of retrieval towards the end of this period of European history, as noted by Emile (2019). At the beginning of the Renaissance era, the main concern regarding medieval artwork was to bring it up to date, which many times required reconstructing missing or deteriorated parts of a canvas, by ðlling in existent gaps with visually pleasing content. Thus, it can be said that almost as old as art itself is the practice of making modiðcations to paintings, in such a way that if an observer would look at the modiðed work of art, without knowing the original, he wouldn’t be able to perceive any alteration. This practice is traditionally carried out by retrieval experts, such as museum art restorers, and it is commonly known as retouching or inpainting. Its desired outcome is to make a damaged artwork more discernible, while restoring its unity. An example of a painting that has been the subject of a manually restoration process, that involved inpainting, is given in following Figure1and Figure2.
Figure 1.
Self-portrait by Margareta Depner - before and after manual restoration
Figure 2.
Left: Damaged Image. Right: Restored Image by Inpainting Technique