Determine the minimum gray value within a selected mask.

gray_erosion_shape calculates the minimum gray value of the input image Image within a mask of shape MaskShape, vertical size MaskHeight and horizontal size MaskWidth for each image point. The resulting image is returned in ImageMin.

If the parameters MaskHeight or MaskWidth are of the type integer and are even, they are changed to the next larger odd value. In contrast, if at least one of the two parameters is of the type float, the input image Image is transformed with both the next larger and the next smaller odd mask size, and the output image ImageMin is interpolated from the two intermediate images. Therefore, note that gray_erosion_shape returns different results for mask sizes of, e.g., 4 and 4.0!

In case of the values 'rhombus' and 'octagon' for the MaskShape control parameter, MaskHeight and MaskWidth must be equal. The parameter value 'octagon' for MaskShape denotes an equilateral octagonal mask which is a suitable approximation for a circular structure. At the border of the image the gray values are mirrored.

Note that gray_erosion_shape requires considerably more time for mask sizes of type float than for mask sizes of type integer. This is especially true for rectangular masks with differnt width and height!

gray_erosion_shape returns 2 (H_MSG_TRUE) if all parameters are correct.

gray_erosion_shape is reentrant and automatically parallelized (on tuple level, channel level, domain level).

gray_erosion, gray_erosion_rect

gray_opening_shape, gray_closing_shape, gray_skeleton

Foundation