Enhancing image quality produced by IR cameras

Abstract

Images produced by IR cameras are a specific source of information. The perception and interpretation of such image greatly depends on thermal properties of observed object and surrounding scenery. In practice, the optimal settings of the camera as well as automatic temperature range control do not guarantee the displayed images is optimal from observer's point of view. The solution to this could be the methods and algorithms of digital image processing implemented in the camera. Such solution should provide intelligent, dynamic contrast control applied not only across entire image but also selectively to specific areas in order to maintain optimal visualization of observed scenery. The paper discusses problems dealing with improvement of the visibility of low-contrast objects and presents method of image enhancement. The algorithm is based on adaptive histogram equalization. The image enhancement algorithm was tested on real IR images. The algorithm significantly improves the image quality and the effectiveness of object detection for the majority of thermal images. Due to its adaptive nature it should be effective for any given thermal image. The application of such algorithm is promising alternative to more expensive opto-electronic components like improved optics and detectors.

Evaluation of hardware implementation of the infrared image enhancement algorithm

“…Differences between visual and thermal images make such direct approach usually ineffective. It is necessary then to carefully choose the applied methods and modify them taking into account specific properties of thermal images [1,2,3].…”

“…The level of incident IR radiation at the detector depends on many factors and emissivity is one of most important [1,2,3]. It is a property of a real object characterizing its ability to radiate energy.…”

“…Differences between visual and thermal images described earlier make such direct approach ineffective. It is necessary then to carefully choose the applied methods and modify them [2,4,6].…”

“…Obviously not only objective factors play important role in perceiving the image but also subjective, human-specific perception of visual information. Thus, even optimal settings of the camera (focus, temperature range, camera placement) do not guarantee successful detection [2,3,10]. The solution to above mentioned problem could be algorithms based on the methods of digital image processing.…”

Single Scale Retinex (SSR) and Multi Scale Retinex (MSR) Enhancement Algorithms for Thermal Night-Vision Images

“…Obviously not only objective factors play important role in perceiving the image but also subjective, human-specific perception of visual information [1]. Thermal images are typically distinct from images registered in the visual spectral domain.…”