July 02 Reviewed: August 2022
FIGURE 1.Methodology principles FIGURE 2
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FIGURE 1.Methodology principles
FIGURE 2. Methodology principles. A widespread type of interference is random additive noise, statistically independent of the video signal. The additive noise model is used when the signal at the output of the imaging system or at some intermediate stage of the transformation can be considered as the sum of a useful signal and some random signal (noise). The additive noise model well describes the effect of film grain, fluctuation noise in radio engineering systems, quantization noise in analog-to-digital converters, etc. [10; 23-24.]. In practice, additive noise is considered as a stationary random field and is characterized by variance and correlation function. Additive noise can be uncorrelated or weakly correlated. Noise sources can be different: 1. Imperfect image capture equipment — video camera, scanner, etc.; 2. Poor shooting conditions — for example, strong noises that occur during night photo/video shooting; 3. Interference during transmission via analog channels — interference from sources of electromagnetic fields, intrinsic noise of active components (amplifiers) of the transmission line. In fact, the gains when using the separability property of the impulse response are much greater. It should be noted that a number of impulse characteristics that often have to deal with in practice are separable. These include: the impulse response described by the Gaussian law, the impulse response having a constant value inside a rectangular window, and some others. Next, you should pay attention to two more significant circumstances that are important to keep in mind when developing a filter. Firstly, it is necessary to set limiters on the brightness of the filtered image before its presentation with an eight-digit code, preventing it from going beyond the accepted dynamic range. The appearance of such brightness values is possible if there are outliers on the transition characteristic of the filter, due, for example, to a sharp decline in the frequency transfer function. In this case, the absence of limiters will lead to overflow of the discharge grid, which will lead to the appearance of black dots and spots on the light areas of the filtered image, and white dots and spots on the dark ones, respectively. The use of limiters of the dynamic range of the signal from the white side and from the black side avoids these artifacts, although it introduces the so-called restriction noise into the filtered image. Secondly, the limitation of the discharge grid leads to a kind of distortion — noise. RESULTS In order to determine the optimal signature of the reference points, experiments were conducted in which the number of reference points and their relative positions changed. In total, three groups of experiments were performed, the initial parameters of which are given below: • for the first group, the number of reference points is four, the location is in the corners of the corrected area (scheme 1, the ‘4 points’ method) (Fig.3); Download 0.5 Mb. Do'stlaringiz bilan baham: |
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