| Popis: |
When machine vision technology is used to detect the inner surface quality of a pipeline,the geometric center of an original image will deviate the center of a pipe wall panoramic annular image in the original one's fore ground area.However,it will lead to serious deviation in the image unwrapped with the geometric center.In order to reduce the measuring errors of the geometry characters,a fast unwrapping algorithm for the panoramic annular image with center deviation was proposed.Firstly,the least square fitting circle method was used to find a fitting circle representing a cross-section of the wall on the image and to obtain the center parameters of panoramic annular image.Then,by unwrapping the panoramic annular image with a quarter circle scanning method and by correcting the frame aspect ratio of the unwrapping image,the panoramic image was completely restored.Experimental results indicate that it takes 0.868 s to unwrap the annular detection area of a panoramic image into a rectangular one with the resolution of 2 044 pixel ×199 pixel,and the relative errors in outline dimensions of the tested targets are less than 1.54%.It is shown that the method could satisfy the real time and accuracy requirements in the image processing. |
