Directional partial differential equation filtering method for striped projection images

A technique of partial differential equation and fringe projection, which is applied in image analysis, image data processing, and the use of optical devices, etc., can solve the problems of obtaining phase information, achieve high calculation accuracy and shorten calculation time

Inactive Publication Date: 2017-02-22
TIANJIN UNIV
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Problems solved by technology

The processing and analysis of the fringe projection image is one of the main means to obtain the shape information of the object to be measured, but because the fringe projection image is always accompanied by strong noise, it is impossible to directly use these images to obtain the phase information correctly, so it is necessary to Filter the FPP stripe image to improve the contrast of the image and remove the influence of noise

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  • Directional partial differential equation filtering method for striped projection images
  • Directional partial differential equation filtering method for striped projection images
  • Directional partial differential equation filtering method for striped projection images

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Embodiment Construction

[0052] The present invention is based on the main steps of the second-order unidirectional PDE filtering method of quasi-wavelet discreteness:

[0053] Step 1, input a fringe projection map u with noise

[0054] Step 2, discretize the image u, assuming that the size of the image u is M×N, u i,j (1≤i≤M,1≤j≤N) is the gray value at point (i, j), and the time step is Δt. During the evolution of the equation, t n = The evolution image at time nΔt is expressed as, The discrete format for constructing direction partial differential equations is:

[0055]

[0056] Among them, θ i,j Indicates the angle between the stripe direction and the x-axis direction, u x , u y Respectively represent the first-order partial derivatives of the image u along the x-axis and y-axis directions, u xx , u yy Respectively represent the second-order partial derivatives of the image u along the x-axis and y-axis directions;

[0057] Step 3: Calculate the angle θ between the stripe direction and ...

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Abstract

The invention belongs to the technical field of optical detection and image processing, proposes a new method for values to solve the partial differential equation, so that the partial differential equation filtering effect is improved. The directional partial differential equation filtering method for striped projection images includes the steps of 1. inputting a stripe projection image u with noise; 2. discretizing a stripe projection image u; 3. calculating the included angles Theta i, j between the strip direction and the x-axis direction; 4. performing adoption to obtain the time step Delta t; 5. performing adoption to obtain the iteration frequency Nc; 6. for the each iteration, obtaining the first-order partial derivative and the second-order partial derivative of each pixel of the image u; 7. obtaining the value solution (as shown in the description) of each pixel of the image u; 8. repeating step 6 and 7 until the set largest iteration frequency Nc is reached to stop the iteration, the value solution (as shown in the description) at this time is a filtering image. The directional partial differential equation filtering method is applied to image processing.

Description

technical field [0001] The invention belongs to the technical field of optical detection and image processing, and relates to a directional partial differential equation filtering method based on a quasi-wavelet discrete format, which is used for filtering fringe images in fringe projection profilometry. Background technique [0002] Fringe Projection Profilometry (FPP) is a very popular three-dimensional shape measurement method in recent years, because it has the advantages of high sensitivity, non-contact, full-field observation, etc., so it is widely used in scientific research and practical engineering Medium [1-3]. The processing and analysis of the fringe projection image is one of the main means to obtain the shape information of the object to be measured, but because the fringe projection image is always accompanied by strong noise, it is impossible to directly use these images to obtain the phase information correctly, so it is necessary to The FPP stripe image is...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/521G01B11/25
CPCG01B11/254
Inventor 唐晨李碧原苏永钢陈明明
Owner TIANJIN UNIV
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