On the focusing of thermal images

Contribution of the temperature of the objects to the problem of thermal imaging focusing

“…This is not the case in the MWIR and LWIR operating ranges, where thermal IR sensors measure simultaneously over broadband wavelength. Thus, while the change is 400nm between the violet and red end of the EM spectrum, in the both MWIR and LWIR spectra the wavelength ranges are 2000nm and 6000nm, respectively [4].…”

Steerable local frequency based multispectral multifocus image fusion

“…In other spectra like thermal and near-infrared, less focus measure works are reported due to unavailability of scene viewing in case of manual focusing, and limited resolution as well as lack of autofocus features in the cameras. Faundez-Zanuy et al [16] addressed the problem of determining the optimal focus position in the thermal images. Zukal et al [9] proposed a focus measure based on interest points detection (IPD) to achieve uniform performance in multispectral imaging.…”

Interest points as a focus measure

“…There exist many other focus measures such as Energy of image gradient (EOG), Sum-modified Laplacian (SML), Tenengrad, Energy of Laplacian of the image (EOL) and many others [4]. In order to evaluate the accuracy of the sharpness measurement based on the interest point detection we selected two methods (EOG, SML) that were used during the comparison and will be described in following sections.…”

“…In order to evaluate the accuracy of the sharpness measurement based on the interest point detection we selected two methods (EOG, SML) that were used during the comparison and will be described in following sections. EOG and SML were selected as the most efficient methods in [4].…”