Unsharp masking for improved quality images taken in mines

Dispatchers in mines and mining areas receive information from CCTV cameras in real time. To enhance the quality of the images received and make the right decisions based on them, it is necessary to apply global methods of digital image processing in conditions of limited information availability. The article analyzes application of the unsharp masking method using a moving average filter with various apertures from 3 to 25. Histograms of the brightness distribution are given for the resulting video frames. The quantitative characteristics, i.e. the average brightness, Tenengrad values, sharpness, allow us to draw a conclusion about the use of a particular filter mask or changing the filter aperture. Analysis of the quantitative characteristics showed the viability of using unsharp masking with apertures up to 13 in general conditions, and up to 9 in conditions of limited information availability. The unsharp masking method was compared with the high-frequency filtering method. The Tenengrad's quantitative characteristics and the sharpness values have shown their efficiency in analyzing the video frame quality. Visual analysis of the video image and the Tenengrad quantitative values and the sharpness values coincide. The use of the unsharp masking method will allow the dispatcher to make efficient decisions based on the informative video data.