In these equations, represents the original image and represents the result of the opening operation by structuring element , which has the function of suppressing noise, based on the definition of opening operation. The gray level of is lower than thegray level of . represents the result of the erosion operation by structuring element after the dilation operation by margin structuring element , namely, the new close operation, which has the function of the detecting star. represents subtracted by the minimum of and , i.e., the modified top-hat transform. If the gray level of is lower than the gray level of , a star is detected and reserved; otherwise, the interference is suppressed. Finally, if , then the pixel of in the image is considered a star pixel, so star segmentation is realized. Each step of the NSTS is shown in Fig. 2.