RESOLUTION ENHANCEMENT OF INFRARED THERMAL IMAGING BY PANSHARPENING ALGORITHMS

Abstract. One common tool in Cultural Heritage inspections is thermal cameras, which are sensitive to the infrared part of the electromagnetic spectrum. But the resolution of these sensors is quite lower than other kinds like visible spectrum range cameras. Typically, the sensors in thermal cameras do not exceed the megapixel frontier. This limitation becomes a problem when trying to combine the information from the thermal images with data from other sensors with much higher resolution such as visible RGB cameras in the same project.

In Remote Sensing, algorithms have been designed to fuse multispectral images with panchromatic images (in origin from satellite platforms) to enhance the resolution of lower resolution images with higher resolution ones. These processes are known as pansharpening. Although pansharpening procedures are widely known, they have not been tested working with thermal imaging. The first approach of merging thermal and visual spectrum images to enhance the resolution of the original thermal image involved applying the intensity-hue-saturation (IHS) algorithm (Lagüela et al., 2012, Kuenzer and Dech, 2013). These works only studied one particular algorithm and they did not include any quality study of the results.

Our work contains a complete review of a bigger pansharpening algorithms’ set and provides an in-depth study of thermal imaging pansharpening, with a numerical assessment. Our research allows the use of thermal sensors with a lower resolution than other types of sensors used simultaneously in the same project.