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Due to the growth of computer crime, an important and urgent problem is the development of methods for detecting the integrity violations of a digital image. In particular, the detection of different types of the image post-processing after their possible forgery is a grey area of information security, and the detection of processing by the Sharpen Filter is an issue practically not covered in open scientific literature. The artificial sharpening of a digital image is the reverse procedure to the blurring. Previously, the authors of the paper developed the method for detecting blur of a digital image based on an analysis of the growth rate of singular values. When blurring, the growth rate of singular values is an order of magnitude smaller than before the blurring, which makes it possible to reveal a threshold value for detecting blurred images. The singular values increase accordingly to the artificially sharpening. But it is not possible to reveal the threshold value in this case. The aim of this paper is to identify the parameters of the digital image matrix, which indicate an artificial sharpening, and to develop a method for detecting sharpness as a digital image post-processing. If the contour is considered as a change in the brightness function of a digital image, then the change in the brightness function will be faster when the contours are sharpened. If two adjacent pixels had the close sharpness values before sharpening, then applying this filter will increase the difference between them. In this paper, the investigation of the close color pairs of an image is carried out when the Sharpness Filter was applied to it. It is revealed that the number of close color pairs during processing decreases. The threshold value which allows separating the processed image from the raw one is empirically established. The method of detecting sharpness as a digital image postprocessing is developed based on the results obtained. [ABSTRACT FROM AUTHOR]

Photos are an integral and certainly an important part of our lives. Often we are faced with a need to increase the clarity of digital image, for example, solving pattern recognition problems, or for other reasons. Methods of increasing the clarity of digital images are very diverse, each has its own range of applicability. However, there may be often artifacts by processing of digital image. The aim of this paper is to increase clarity of digital image with the possibility of avoiding artifacts. To achieve this aim the researchers used digital image processing algorithms, based on using different convolution matrix types. There are shown in typical images with increasing clarity of digital image what advantages is the use of combinations of these algorithms in a specific sequence. A comparative analysis of the impact of different filters to increase the clarity of digital images was conducted and gives recommendations by using them. [ABSTRACT FROM AUTHOR]