Dental X-ray Image Enhancement Based on Human Visual System and Local Image Statistics

An X-ray/Clincal medical image generally suffers from low contrast quality and degradations which vary from one region to another. Extraction of features in medical science and image processing is a matter of study and research. X-rays contain high redundancy, as far as background information is considered and in a way govern local image statistics. Contrast enhancement techniques based on visual perception criterion [1][2], deal in use of local (3x3) edge operators for computation of local image statistics of non-filtered images for contrast modification. In context to our earlier work and findings in [3], we suggest the use of LoG filter for contrast improvement process in place of methods discussed in [1][2]. An adaptive technique is suggested to improve the contrast quality of dental X-ray image using the Laplacian-of-a-Gaussian (LoG) Filter. Biologically, LoG Filter has a similar profile to the response of the receptive fields in the Human Visual System (HVS) [4]. Here, the results obtained reveal that LoG Filter is the best choice, whose standard deviation parameter sigma ‘σ’ can be conveniently used to tune the pixel value to a maximum gray value of 255.000000 and a minimum gray value of 0.000000 in our process of contrast modification. A description, an implementation, an estimate of the contrast gain and comparison of performance of various edge detectors is presented. Implementation of LoG Filter serves to be the best choice in the process of contrast modification and achieve high contrast gain.