4 results about "Image edge" patented technology

The invention discloses a method for evaluating the quality of an image shot by an unmanned aerial vehicle, which is characterized in that for an image shot by the unmanned aerial vehicle in patrol inspection, the quality of the image is analyzed from the whole image and local details; for blurring generated by focusing misalignment caused by motions or shakes of the unmanned aerial vehicle, a frequency domain sharpness index and the distribution density and orientation features of edge segments in a space domain are firstly fused so as to judge whether an image captured by the unmanned aerial vehicle image is blur or not on the whole; under the condition that the image quality is acceptable on the whole, salient edge regions in the image are further searched, and the local detail blur degree of image edges is judged through analyzing the average width of difference salient edges. The method is applied to images shot by the unmanned aerial vehicle under outdoor conditions, the image quality can be effectively evaluated under various complex backgrounds without being influenced by the image content, and the evaluation is consistent with subjective evaluation of people in grade.

The disclosure provides an approach for image segmentation from an uncalibrated camera array. In one aspect, a segmentation application computes a pseudo depth map for each frame of a video sequence recorded with a camera array based on dense correspondences between cameras in the array. The segmentation application then fuses such pseudo depth maps computed for satellite cameras of the camera array to obtain a pseudo depth map at a central camera. Further, the segmentation application interpolates virtual green screen positions for an entire frame based on user input which provides control points and pseudo depth thresholds at the control points. The segmentation application then computes an initial segmentation based on a thresholding using the virtual green screen positions, and refines the initial segmentation by solving a binary labeling problem in a Markov random field to better align the segmentation with image edges and provide temporal coherency for the segmentation.

The invention discloses a PET image reconstruction method based on non-local features and total variation joint constraint. The method comprises the following steps: establishing a mathematical modelof a reconstruction problem, adding the low-rank constraint based on non-local features and adding the total variation constraint to perform PET image reconstruction. The low-rank constraint filters noises in the structural information of an image according to the non-local similarity feature of the image. Meanwhile, the defect that a step effect exists in the total variation method is overcome. The total variation serves as a constraint for edge protection and noise reduction based on pixel points. At the same time, the defect that the edge of an image exists on the basis of an image block isovercome. The convergence speed is accelerated. Therefore, the constraint joint solving means is effectively utilized, and the defects of two methods are overcome. The problems that the result is lowin resolution and the noise interference is generated in the PET image reconstruction process can be further solved. Compared with an experiment of an existing reconstruction method, the reconstruction method disclosed by the invention has the advantage that a good reconstruction effect can be obtained.

The invention relates to a videodisc center positioning method according to fundus image edge information and brightness information. The method comprises the steps of preprocessing a fundus image; extracting a vertical edge image and a horizontal edge image of the fundus image after contrast reinforcement by means of an Isotropic Sobel operator, performing positioning for obtaining a horizontal coordinate of the videodisc according to an edge difference curve; extracting a blood vessel density characteristic and a videodisc brightness characteristic; defining a product of the blood vessel density characteristic and the videodisc brightness characteristic as a comprehensive characteristic value of the vertical coordinate, and obtaining a comprehensive characteristic value curve which is related with the vertical coordinate, wherein the coordinate which corresponds with the maximum value on the curve is the vertical coordinate of the videodisc. The videodisc center positioning method has an advantage of high positioning accuracy.