10.39 The objects and background in the image below have a mean intensity of 170 and 60, respectively, on a [0, 255) scale. The image is corrupted by Gaussian noise with mean and a standard devia- tion of 10 intensity levels. Propose a thresholding method capable of a correct segmentation rate of 90% or higher. (Recall that 99.7% of the area of a Gaussian curve lies in a $30 interval about the mean, where o is the standard deviation.)