Quantitative Schlieren Image-Noise Reduction Using Inverse Process and Multi-Path Integration

• 作者: Ahmad Zaid Nazari Fumiya Ito Harumi Kondo Ryoya Yamada Shinichiro Nakao Takanori Motohiro Yojiro Ishino Yoshiaki Miyazato Yu Saiki
• 来源期刊: 流量控制、测量及可视化(英文)
• 学科: 物理学
• 关键词: Noise Reduction Technique INVERSE Process QUANTITATIVE SCHLIEREN Optical System Complex SCHLIEREN BRIGHTNESS COMPUTERIZED Tomography (CT)
• 年，卷（期）: 2020,（2）
• 页码范围: 25-44
• 页数: 20页
• 分类号: O42

摘要

This report deals with introducing two new techniques based on a novel concept of complex brightness gradient in quantitative schlieren images, “inverse process” and “multi-path integration” for image-noise reduction. Noise in schlieren images affects the projections (density thickness) images of computerized tomography (CT). One spot noise in the schlieren image appears in a line shape in the density thickness image. Noise effect like an infectious disease spreads from a noisy pixel to the next pixel in the direction of single-path integration. On the one hand, the noise in the schlieren image reduces the quality of the image and quantitative analysis and is undesirable;on the other it is unavoidable. Therefore, the importance of proper noise reduction techniques seems essential and tangible. In the present report, a novel technique “multi-path integration” is proposed for noise reduction in projections images of CT. Multi-path integration is required the schlieren brightness gradient in two orthogonal directions. The 20-directional quantitative schlieren optical system presents only images of schlieren brightness in the horizontal gradient and another 20-directional optical system seems necessary to obtain vertical schlieren brightness gradient, simultaneously. Using the “inverse process”, a new technique enables us to obtain vertical schlieren brightness gradient from horizontal experimental data without the necessity of a new optical system and can be used for obtaining any optional directions of schlieren brightness gradient.