Digital Restoration of Old Paintings

Paintings are made up of materials that can suffer damage with the passage of time. To protect them over a long period, they are coated with a protecting covering of varnish layer. The varnish layer over paintings is affected by atmospheric conditions, fluctuations in temperatures, humidity and sunlight. Over a period of time, the transparency of the varnish becomes clouded and discolored, often resulting in a picture being viewed as if through an amber or even brown or black filter. We analyze the effect of varnish layer on the visual appearance of old paintings and provide the correlation of degradation with the quantitative measures such as entropy and standard deviation of the points cluster of the image in the color space. We further develop a method of color restoration by appropriately transforming the color space. We provide both an interactive method and an automated examplebased method. In addition to the color degradation, cracks which appear apparently on the surface, are also caused by the aging process. As a result of cracks and color degradation, paintings may lose their aesthetic and historical values. In this paper, we also integrate crack detection with color restoration.