Application of a Sequential Methodology for the Digital Processing of Rock Art Images in the Isthmus of Panama

Abstract

This work presents the results of the application of a series of sequential analyses of a digital image of rock art obtained at the Piedra del Sol site, located in central Panama. In this sequence, we propose the application of (i) median filtering for the elimination of high-frequency components present in the original image; (ii) a process of stretching histogram that seeks to improve the contrast of the image by means of stretching of the range of density values; (iii) a simple thresholding process where the grayscale image is converted to a binary or two-level scale; (iv) edge detection using several computational codes based on image segmentation; and (v) a negative representation of the obtained edges. The structure of the sequential code used in this study is based on MATLAB functions. The detection of the edges of the images obtained over the nine threshold levels between 0 and 1, as a product of the result obtained from the histogram stretching process by defining a window of maximum and minimum intensities of [0 0.7] and [0.7 0], which, in turn, of the application of the filter through the median for a mask (2 × 2), allowed us to better define the elements that characterize the rock art of Piedra del Sol. In summary, this low-cost technique can offer valuable information on rock art, starting a complete database of these cultural features made by the ancient indigenous societies of the Isthmus of Panama.