Double-threshold image segmentation method based on gray gradient

Abstract

For the segmentation of the dim point target and the extended target under sky background which has low resolution, an automatic thresholding method based on spatial gradient information is presented. It can separate the point target and the extended target from the background even under the strong noise condition, providing good segmentation results for the point target as well as the accurate information of the shape for the extended target. This method first marks the pixels as the background or the target using the image gray gradient roughly, then fit the grayvalue of pixels in the background area to obtain two thresholds, with which the image can be segmented according to the pixel position, and finally the morphological filter is adopted to remove the noise in the segmented image. The experiment shows that, when compared to Otsu in low resolution images with even background, our method can work more accurately and robustly.