Showing papers on "Dark-frame subtraction published in 1978"
TL;DR: The restoration of images degraded by film-grain noise is considered in the context of estimation theory and a discrete Wiener filer is developed which explicitly allows for the signal dependence of the noise.
Abstract: Film-grain noise describes the intrinsic noise produced by a photographic emulsion during the process of image recording and reproduction. In this paper we consider the restoration of images degraded by film-grain noise. First a detailed model for the over-all photographic imaging system is presented. The model includes linear blurring effects and the signal-dependent effect of film-grain noise. The accuracy of this model is tested by simulating images according to it and comparing the results to images of similar targets that were actually recorded on film. The restoration of images degraded by film-grain noise is then considered in the context of estimation theory. A discrete Wiener filer is developed which explicitly allows for the signal dependence of the noise. The filter adaptively alters its characteristics based on the nonstationary first order statistics of an image and is shown to have advantages over the conventional Wiener filter. Experimental results for modeling and the adaptive estimation filter are presented.
58 citations
18 Apr 1978
TL;DR: The use of birefringent systems permits the recording, in a single exposure, of several different granularity figures as discussed by the authors, which can be used to obtain, in the focal plane of the recording plate of A and B exactly superposed, the profile of the interference fringes which would be given in fact by three exposures, made by alternating the images (A, B, A, A), with the respective exposure times 1/2, 1, 1.1/2.
Abstract: The use of birefringent systems permits the recording, in a single exposure, of several different granularity figures. In two exposures, one with the image A, the other with the image B, we can obtain, in the focal plane of the recording plate of A and B exactly superposed, the profile of the interference fringes which would be given in fact by three exposures, made by alternating the images (A, B, A), with the respective exposure times 1/2, 1, 1/2. The signal/noise ratio is thus ten times greater than that which is given in the case of two poses in the absence of birefringent crystal.© (1978) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
1 citations