Сontrast evaluation of digital aerial and satellite images

Abstract

The article shows the relevance of numerical evaluation of digital aerial and satellite images’ contrast as one of their main characteristics, which is important for photointerpretation. The formulae for expressing the numerical values of the contrast from a variety of sources are presented and analyzed. An example of images and their contrast with different formulae clearly show the inadequacy of the estimates of the contrast for some of the formulae and it allows you to select the most appropriate mathematical expression of the contrast. Enhancements to expressions numerical parameters for an evaluation of the contrast of the digital image were proposed. One of the proposed formulae is appropriate for general evaluation and another one for the assessment of local contrast, which can also be used to assess the effectiveness of the use of the entire scale of possible brightness values of the pixels, i.e. the bit of the digital image. Examples of evaluation of using these formulae were given.