Efficient focus assessment for a computer vision-based Vickers hardness measurement system

Andreas Maier; Georg Niederbrucker; Sebastian Stenger; Andreas Uhl

doi:10.1117/1.JEI.21.2.021114

15 May 2012 Efficient focus assessment for a computer vision-based Vickers hardness measurement system

Andreas Maier, Georg Niederbrucker, Sebastian Stenger, Andreas Uhl

Author Affiliations +

Journal of Electronic Imaging, Vol. 21, Issue 2, 021114 (May 2012). https://doi.org/10.1117/1.JEI.21.2.021114

Abstract

A large variety of computationally lightweight functions used for assessing image sharpness in the spatial domain is evaluated for application in a passive autofocus system in the context of microindentation-based Vickers hardness testing. Alternatively, the file size of compressed JPEG images is proposed to determine image sharpness. The functions are evaluated on a significant dataset of microindentation images with respect to their properties required for focus search and sharpness assessment, their robustness to downsampling the image data, and their computational demand. Experiments suggest that of all spatial domain techniques considered, the simple Brenner autofocus function is the best compromise between accuracy and computational effort, while JPEG file size is a versatile solution when the application context allows.

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Andreas Maier, Georg Niederbrucker, Sebastian Stenger, and Andreas Uhl "Efficient focus assessment for a computer vision-based Vickers hardness measurement system," Journal of Electronic Imaging 21(2), 021114 (15 May 2012). https://doi.org/10.1117/1.JEI.21.2.021114

Published: 15 May 2012

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