A novel method for semiautomated assessment of directions of collagen fibers in soft tissues using histological image analysis is presented. It is based on multiple rotated images obtained via polarized light microscopy without any additional components, i.e., with just two polarizers being either perpendicular or nonperpendicular (rotated). This arrangement breaks the limitation of 90° periodicity of polarized light intensity and evaluates the in-plane fiber orientation over the whole 180° range accurately and quickly. After having verified the method, we used histological specimens of porcine Achilles tendon and aorta to validate the proposed algorithm and to lower the number of rotated images needed for evaluation. Our algorithm is capable to analyze 5·105 pixels in one micrograph in a few seconds and is thus a powerful and cheap tool promising a broad application in detection of collagen fiber distribution in soft tissues.

1st Department of Pathology St Anne's University Hospital Brno and Faculty of Medicine Masaryk University Pekařská 664 53 656 91 Brno Czech Republic

Brno University of Technology Faculty of Mechanical Engineering Institute of Physical Engineering Technická 2896 2 Brno 616 69 Czech Republic

Brno University of Technology Faculty of Mechanical Engineering Institute of Solid Mechanics Mechatronics and Biomechanics Technická 2896 2 Brno 616 69 Czech Republic

Department of Anatomy Faculty of Medicine Masaryk University Kamenice 126 3 Brno 625 00 Czech Republic

Technical University Ostrava Faculty of Mechanical Engineering Department of Applied Mechanics 17 Listopadu 15 Ostrava 708 33 Czech Republic

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Full-Range Optical Imaging of Planar Collagen Fiber Orientation Using Polarized Light Microscopy