IMPROVED-SDROM filtering for scratches removal from images
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IMPROVED-SDROM filtering for scratches removal from images Mansour Hamdani 1
& Mohamed Faouzi Belbachir
1
Received: 12 March 2019 / Revised: 8 May 2020 / Accepted: 15 June 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
This article is dedicated to the detection and correction of scratches found in old movies. The method we propose is based on the SDROM method (Signal Dependent Rank Ordered Mean) which corrects only the pixels of the detected scratches. A statistical study of the noised images by scratches shows that the amplitude difference of the neighboring pixels in an image outside the scratch is small (less than 10 Gy levels). We find that the scratch can be characterized by a high difference of amplitude of its edges pixels, we propose an approach called IMPROVED SDROM, is constituted by three stages. First for the detection of the scratches we use two neighboring sliding windows (3 × 3 pixels) sweeping the entire image. We show that Δ = m2m1 (with m1 and m2 the averages of the two windows), is a relevant parameter for the detection of pixels that can belong to a stripe. The average of each window is calculated after a pretreatment. Then we locate the stripes and their widths and finally we make the correction by a simple interpolation. Unlike the SDROM method, our approach allows to locate scratches of any width, with simplicity of treatment certainly allows a gain in processing time compared to other methods that will be mentioned in what follows. A study of a set of examples of scratches obtained by simulation and also on real scratches illustrates the validity of our approach. Keywords Detection . Scratches . Restoration of old movies . Interpolation
1 Introduction The vertical scratch is a frequent deterioration of old films. It is generally due to the friction of the film with a particle of dust or a metal part belonging to the visualization mechanism. This
* Mansour Hamdani [email protected] Mohamed Faouzi Belbachir [email protected]
1
Institute of Electronics, Laboratory of Signals, Systems and Data, University of Science and Technology Oran- Mohamed Boudiaf, Oran, USTO, Algeria
Multimedia Tools and Applications
degradation is obtained during the diffusion of the film. It is characterized by a line lighter or darker than its immediate vicinity, almost vertical and presents on several consecutive images [1–4]. The vertical scratch obscures partially or totally, the initial information contained in the image, causing an attenuation of the light intensity [4]–[5]. This deterioration is also characterized by its temporal duration, its position within an image, its orientation, as well as its width (from 1 to 10 pixels). It can be visible on all or a large part of the height of the image. It will be named by main scratch when it is visible on more than 50% of the height of the image; otherwise one is in the presence of a secondary scratch. Vertical scratch detection can be problematic in some cases. For slight alterations in light intensity, the s
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