Abstract
This paper reports the precision of shape-from-focus (SFF) imaging according to the texture frequencies and window sizes of a focus measure. SFF is one of various depth measurement techniques for optical imaging, such as microscopy and endoscopy. SFF measures the depth of an object according to focus measure, which is generally computed with a fixed window. The window size affects the performance of SFF and should be adjusted for the texture of an object. In this study, we investigated the precision difference of SFF in texture frequencies and by window size. Two experiments were performed: precision validation in texture frequencies with a fixed window size, and precision validation in various window sizes related to pixel-cycle lengths. The first experimental results showed that a smaller window size could not provide a correct focus measure, and the second results showed that a window size that is approximately equal to a pixel-cycle length of the texture could provide better precision. These findings could potentially contribute to determining the appropriate window size of focus measure operation in shape-from-focus reconstruction.
Highlights
Electronics 2021, 10, 1870. https://Measurement of the three-dimensional (3-D) shape of an object continues to be an interesting topic in the field of sensing
In the SFF precision, the window size of the focus measure operator might be related to the pixel-cycle length of a texture
The depth was measured with the fixed window size for various pixel-cycle length textures
Summary
Electronics 2021, 10, 1870. https://Measurement of the three-dimensional (3-D) shape of an object continues to be an interesting topic in the field of sensing. Accurate 3-D shape measurement is necessary for the validation and inspection of an object, e.g., for comparison between CAD models and 3-D scans. Many methods for 3-D shape measurement have been proposed, e.g., laser scanning and optical image processing. Stereoscopic 3-D measurement with two or more cameras is a representative method of optical image processing, and is employed in many cases. Shape estimation via illumination difference, i.e., shape-from-shading, is another option for achieving measurement with a single camera. This works well on a smooth and textureless surface; it is very difficult to distinguish the illumination from the texture itself according to brightness.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
