30 results about "Nonlinear diffusion" patented technology

The invention discloses a fingerprint image enhancing method, and belongs to the technical field of image processing. The method comprises the following steps of: performing gray shearing and gray stretching on fingerprint foreground region image gray to obtain fingerprint foreground region image gray2; performing Gaussian filtration on the fingerprint foreground region image gray2 by using a Gaussian filter g sigma, and calculating a normalized fingerprint gradient vector; then constructing a structure tensor, and calculating the direction field of fingerprint ridge lines; and finally, constructing two one-dimensional anisotropic filters to perform two-time filtration enhancement on the fingerprint foreground region image gray2 to obtain a final filtration enhanced fingerprint foregroundregion image. Based on a nonlinear diffusion model and the normalized structure tensor, the method can effectively remove various structural noises, reduce the dynamic change range between the fingerprint ridge lines and the valley lines and connect certain broken fingerprint ridge lines at the same time. The method has good enhancement effect and characteristic of effectively saving the time, and can meet the requirement of on-line fingerprint identification.

The invention is a method of developing a sedimentary basin from a stratigraphic simulation of multilithologic filling accounting for fine sediment transport. The sedimentary basin is divided into geologic layers with each geologic layer being subdivided into a series of climatic layers. Each climatic layer is associated with at least one constant climatic parameter. A stratigraphic simulation is performed within each climatic layer using a stratigraphic model. The sediment transport in the continental domain and sediment bottom layer transport in the marine and lacustrine domains are modelled using nonlinear diffusion equations under maximum erosion rate constraint. Suspended sediment transport in the marine and lacustrine domain is modeled using an advection-diffusion equation accounting for a particle fall rate and of a marine and lacustrine current velocity. The climatic layers belonging to a single geologic layer are then homogenized and the basin is developed according to the stratigraphic simulation results.

The invention discloses a low-dose computed tomography (CT) image processing method based on wavelet space directional filtering, belonging to the technical field of computerized tomography. The method is as follows: firstly, static wavelet transform is used for carrying out single-layer decomposition on the low-dose CT image to be processed, then high-frequency detailed images in the horizontal,vertical and opposite angle directions are subjected to one-dimensional nonlinear diffusion filtering in the vertical and horizontal directions respectively so as to restrain the information intensity of star-strip artifacts in high-frequency detailed images in different directions, and then inverse static wavelet transform is conducted according to the processed high-frequency detailed images inthe horizontal, vertical and opposite angle directions and the original low-frequency images for rebuilding to obtain artifacts so as to obtain restrained CT images, finally, the image is further processed by using the existing large adjacent region weighted average noise suppression method. By utilizing the method, the star-strip artifacts and noise in the low-dose CT image can be effectively restrained, and the quality of the low-dose CT image can be improved, so that the low dose CT image meets the quality requirements of clinical diagnosis.

The present invention relates to blood flow reserve fraction, and in particular to a method for obtaining vascular blood flow reserve fraction. The non-linear diffusion filter of the differential equation denoises the sequence image data; C. Segments the blood vessel image from the background image; D. Performs wavelet edge detection on the blood vessel image, and extracts the edge of the blood vessel image by decomposing the mutation point of the image E. Obtain the vascular blood flow reserve fraction according to the time interval between the vascular image and each frame of image; A method for obtaining fractional blood flow reserve, and a corresponding device.

Embodiments of the present invention provide a spectral denoising method and a processor. The method includes: obtaining the spectrum to be denoised; determining the gradient information of the spectrum to be denoised; determining the time modulation function through the gradient information; adjusting the preset nonlinear diffusion function according to the time modulation function; Denoising spectra for iterative denoising. By determining the time modulation function to adjust the nonlinear diffusion function, and then iteratively denoising the spectrum to be denoised according to the adjusted nonlinear diffusion function, the effective adjustment of the spatial nonlinear filter operator for the diffusion time is realized, and high-precision The local peak information of the spectrum in the process of denoising the spectral information is preserved.

A method for extracting a differential signal and a differentiator, wherein the method includes: step 1, calculating a first integral signal z0 according to an output signal u of the differentiator, and calculating an error signal based on the first integral signal z0 and an input signal; step 2, Calculating a second integral signal according to the error signal; step 3, constructing a nonlinear softening model according to the second integral signal and the error signal, and calculating a differential signal of the input signal according to the nonlinear softening model. According to the computer construction error and its integral, the method can use the nonlinear softening model to realize the extraction of the approximate differential of the input signal. Compared with the existing differential signal extraction method, the method not only has lower implementation cost, but also has higher precision of the extracted differential signal.