A Visual Enhancement Method of Schlieren Features Based on Correlation Frame Constraints

Abstract

The invention relates to a schlieren feature visualization enhancement method based on associated frame constraints, which belongs to the field of high-speed target schlieren detection. The method collects high-dynamic schlieren sequence images through a background schlieren imaging system based on compression sampling, then uses Gaussian filtering to perform denoising preprocessing on the collected schlieren sequence images, and uses the KLT-RANSAC algorithm to perform image processing on the schlieren sequence images. Registration to obtain stable sequence images; finally, for the temporal correlation of high dynamic schlieren sequence images, the optical flow method is used to detect and output the motion vector of each pixel between two frames of images. The method is aimed at the problems of fast time-varying schlieren sequence images and the missing acquisition and indistinguishability of schlieren parameters caused by rich sharp and weak schlieren information, and considers the relevance of moving images in the time dimension to solve the problem of traditional optical flow methods. Under the influence of noise, the extraction accuracy of the schlieren area between multiple frames is low, and the vector accuracy of the schlieren in the high dynamic motion sequence image is improved.

Description

technical field [0001] The invention specifically relates to a schlieren feature visualization enhancement method based on associated frame constraints, and belongs to the field of high-speed target schlieren detection. Background technique [0002] Background Schlieren technology, that is, Background Oriented Schlieren, referred to as BOS, is a non-contact optical flow field measurement method combined with schlieren technology and digital image processing technology. Its principle is: the air is compressed due to the high-speed movement of the target. It will lead to changes in the refractive index, so the light will be deflected, and the gradient and density distribution of the flow field during the flight of the supersonic vehicle can be quantitatively calculated by analyzing the deflection of the light. BOS technology breaks through the limitations of traditional methods that can only be tested in wind tunnels. It can calculate the density, pressure, velocity, momentum,...

AI Technical Summary

Problems solved by technology

The motion vector obtained by the cross-correlation method is only the maximum possible displacement in probability, and the calculated schlieren image has a low resolution

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