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PIV image processing method and system

An image processing and image technology, applied in the field of image processing, can solve problems such as calculation errors, resolution bottlenecks, and inability to achieve, and achieve the effect of consuming less computing resources, reducing processing time, and improving processing results.

Active Publication Date: 2019-09-17
SHANGHAI JIAO TONG UNIV
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Problems solved by technology

When the interpretation area is too small, calculation errors will occur due to the low signal-to-noise ratio, so there is a bottleneck in the resolution
[0007] 3. When the velocity gradient of the flow field is large, the interpretation grid will be severely deformed, resulting in a decrease in correlation, resulting in a matching error in the interpretation area
[0009] 1. The accuracy is high only when dealing with small displacements, and it cannot handle large-span displacements
[0010] 2. Processing accuracy is greatly affected by image noise
[0011] In the current PIV experiment, it is necessary to obtain a higher resolution displacement field to analyze the details of the flow field, but this effect cannot be achieved by the current algorithm

Method used

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Experimental program
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Embodiment 1

[0078] like Figure 1-6 As shown, the application of the present invention provides a PIV super-resolution analysis method based on image reconstruction hybrid algorithm, such as figure 2 As shown, it mainly includes the steps of estimating the displacement field, image reconstruction, correcting the displacement field, and iterative processing.

[0079] like figure 2 Shown is an implementation example of displacement field estimation based on cross-correlation algorithm, which mainly includes displacement field estimation, image reconstruction, and optical flow calculation modules. The original PIV images A and B are preprocessed by means of CLAHE (adaptive equalization), high-pass filtering and maximum intensity limitation to obtain pictures I, I′.

[0080] On this basis, the standardized discrete cross-correlation function was used to match the interpretation area. Define I(i, j) as the light intensity of the pixel at the coordinates (i, j) in the picture, and the aver...

Embodiment 2

[0123] like Figure 1-6 As shown, the application of the present invention provides a PIV image processing system, including an estimated displacement field module, an image reconstruction module, and a modified displacement field module:

[0124] The estimated displacement field module processes and obtains the estimated value of the displacement field of the PIV original image A, B based on a cross-correlation method;

[0125] The image reconstruction module reconstructs image A to obtain reconstructed image B';

[0126]The modified displacement field module analyzes the reconstructed image B' and image B to obtain a modified displacement field.

[0127] The processing steps of the estimated displacement field module using the cross-correlation method on the PIV original image are: preprocessing the original PIV images A and B by CLAHE, high-pass filtering and maximum intensity limitation methods to obtain the PIV experimental images I and I respectively ’, and then apply ...

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Abstract

The invention provides a PIV image processing method and system in the technical field of image processing. The method comprises the following steps of S1, estimating a displacement field, preprocessing an original PIV image A and an original PIV image B based on a cross-correlation method, and performing two-dimensional linear interpolation on the displacement fields of the obtained images A and B to enable the displacement vectors in the displacement field to be in one-to-one correspondence with pixels of a PIV experimental image to obtain an estimated displacement field; S2, carrying out image reconstruction, reconstructing the image A by using the displacement field estimation value obtained in the step S1 to obtain a reconstructed image B '; S3, correcting the displacement field, analyzing the reconstructed image B' and the image B based on an optical flow method to obtain the corrected displacement field; and S4, carrying out iteration processing, iterating the step S2 and the step S3. The method integrates the advantages of a cross-correlation method and an optical flow method, has a very good processing effect on a PIV experimental image in a high dynamic range, and solves the contradiction that the large-displacement and sub-pixel-level displacement calculation precision cannot be met at the same time.

Description

technical field [0001] The present invention relates to the technical field of image processing, and in particular, to a PIV image processing method and system. Background technique [0002] Particle image velocimetry (PIV) is a common non-invasive quantitative velocity measurement technology, which is widely used in the measurement of fluid velocity field because of its characteristics of full flow field, high precision and no interference to fluid motion. [0003] Improving the precision, spatial resolution and dynamic range of PIV image processing will help improve the level of flow analysis in PIV experiments. The current PIV digital image processing methods mainly include cross-correlation and optical-flow. [0004] The cross-correlation method is a statistical method based on correlation convolution, and its defects are as follows: [0005] 1. Due to the use of discrete convolution functions, this method cannot obtain displacement vector results with sub-pixel precis...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/207G06T7/269G06T3/40G01P5/22G01P5/00
CPCG01P5/001G01P5/22G06T3/4053G06T7/207G06T7/269
Inventor 陈方田沛东
Owner SHANGHAI JIAO TONG UNIV