New Visualization Technique Improves Perception of Details

A technique that combines histogram equalization with dynamic-range compression significantly enhances the visual quality of high-dynamic-range IR images

Sight Enhancement through Video Fusion in a Surveillance System

In this paper we consider the problem of fusing two video streams acquired by an RGB camera and a sensor operating in the long wave infrared (LWIR). The application of interest is area surveillance and the fusion process aims at enhancing the human perception of the monitored scene. We propose a fusion procedure where the background and the moving objects are separated and fused by means of different strategies. With respect to standard video fusion techniques this approach has the advantage of reducing the computational load and mitigating the rapid brightness variations in the fused video. It is also less sensitive to the presence of noise. We discuss the experimental results obtained on a typical area surveillance scenario and demonstrate the effectiveness of the proposed method. For this purpose, the analysis is carried out both subjectively, in terms of visual quality of the fused video stream and objectively, in terms of standard image quality indexes. The computational load is also evaluated

Dynamic Range Compression and Contrast Enhancement in Infrared Imaging Systems

Third-generation thermal cameras have high dynamic range (up to 14 bits) and collect images that are difficult to visualize because their contrast exceeds the range of traditional display devices. Thus, sophisticated techniques are required to adapt the recorded signal to the display, maintaining, and possibly improving, objects’ visibility and image contrast. The problem has already been studied in relation to images acquired in the visible spectral region, while it has been scarcely investigated in the infrared. In this work, this latter subject is addressed, and a new method is presented that combines dynamic-range compression and contrast enhancement techniques to improve the visualization of infrared images. The proposed method is designed to meet typical requirements in infrared sensor applications. The performance is studied through experimental data and compared with that yielded by three well-established algorithms. Evaluation is performed through subjective analysis, assigning each algorithm a score on the basis of the average opinion of human observers. The results demonstrate the effectiveness of the proposed technique in terms of perceptibility of details, edge sharpness, robustness against the horizon effect, and presence of very warm objects

Dynamic range compression and contrast enhancement in IR imaging systems

The visualization of IR images on traditional display devices is often complicated by their high dynamic range. Classical dynamic range compression techniques based on simple linear mapping, reduce the perceptibility of small objects and often prevent the human observer from understanding some of the important details. Thus, more sophisticated techniques are required to adapt the recorded signal to the monitor maintaining, and possibly improving, object visibility and image contrast. The problem has already been studied with regard to images acquired in the visible spectral domain, but it has been scarcely investigated in the IR domain. In this work, we address this latter subject and propose a new method for IR dynamic range compression which stems from the lesson learnt from existing techniques. First, we review the techniques proposed in the literature for contrast enhancement and dynamic range compression of images acquired in the visible domain. Then, we present the new algorithm which accounts for the specific characteristics of IR images. The performance of the proposed method are studied on experimental IR data and compared with those yielded by two well established algorithms

Aorto-coronary dissection during angioplasty in a patient with history of radiation therapy for breast cancer.

Aorto-coronary dissection during angioplasty in a patient with history of radiation therapy for breast cancer