A ray negative image exposure quality evaluation method based on main target area constraint

Abstract

The invention discloses a ray negative image exposure quality evaluation method based on main target area constraint. The method comprises the following steps of analyzing a negative image by using aself-adaptive weight area method, and carrying out area division on the negative image to obtain a main target area; determining an average brightness target value and a threshold value of a main target area of the negative film image with normal exposure through an experiment; calculating the average brightness of the main target area of the negative image automatically through an algorithm and compared with a target value, and then judging whether the image is exposed or not. The method solves the problems that the subjectivity is high and the method is easily interfered by factors such as the performance of a display when whether the digital image of the industrial ray negative film is normally exposed or not is manually judged. The feasibility of the method is verified through an instance analysis result, and meanwhile, the exposure assessment method provided by the invention has the advantages of automation, rapidness and accuracy, and can be used for research on digital archivingof industrial ray negative films.

Description

technical field [0001] The invention belongs to the technical field of image processing, and in particular relates to a radiation film image exposure quality evaluation method based on main target area constraints. Background technique [0002] With the advent of the information age, it is becoming more and more important to digitize traditional radiographic film digitizers. At present, most industrial radiographic film digitizers on the market use industrial cameras to shoot film. If the photographed film image exists A certain overexposure or underexposure will cause the loss of film information, which has buried deep hidden dangers for the digital archiving of film and the quality traceability in the later stage. [0003] The traditional method of judging whether the exposure of the film image is normal is to observe with the naked eye, but this method is not only easily affected by human subjective factors, but also closely related to the performance parameters such as t...

AI Technical Summary

Problems solved by technology

However, there are problems such as the large blackness of the film itself, the exposure compensation method is backlight, and there are many interference areas in the film image, so it is difficult to determine its target value and threshold when using the average brightness algorithm, weighted mean algorithm, and brightness histogram algorithm. According to the definition of image entropy, the more uniform the grayscale distribution of the grayscale image, the better, but for the film image, the uniform grayscale distribution must have overexposure or underexposure, so the image entropy algorithm is not suitable for the evaluation of the exposure quality of the film image

Therefore, the current automatic exposure algorithm is not suitable for evaluating the exposure quality of industrial radiography film images.

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