Glare: A free and open-source software for generation and assessment of digital speckle pattern

Abstract

Generating digital speckle image and its corresponding deformed image is the basis of digital image correlation research. At present, however, it still lacks a powerful, easy-to-use, and user-friendly professional software concerning generation and assessment of digital speckle pattern. Researchers have to reimplement the generation algorithms in literature by themselves, which is time-consuming and error-prone. This paper reports a free and open-source software, Glare, for generation and assessment of digital speckle pattern. Glare has functions including generating speckle patterns, rendering deformed images, assessing pattern quality, and presenting pattern recommendations: Glare can generate ellipse, polygon, and Gaussian speckle patterns; can render deformed images with underlying deformation fields of translation, stretch/compression, rotation, sinusoidal deformation, Gaussian deformation, and Portevin-Le Chatelier band deformation; can calculate key pattern quality assessment parameters such as speckle coverage, speckle size, systematic error, and random error; can produce optimized speckle pattern in form of vector image. The software realizes real-time deformed image rendering with the aid of fast initial value estimation algorithm for backward mapping and pattern pre-rendering technique, and improves the computational efficiency of sum of square of subset intensity gradients by integral image method. In general, the software can be used not only for scientific research and engineering applications in digital image correlation community but also for education of experimental mechanics, and therefore has broad prospects.