Get the value of the mask image
| x | Specifies the x coordinate (in the image coordinates of the layer) for which you want to get the value. |
| y | Specifies the y coordinate (in the image coordinates of the layer) for which you want to get the value. |
Mask image value (0 to 255)
Gets the value (0 to 255) at any position in the layer mask image (the image that retains opacity).
An exception is thrown if you specify an invalid (out of range) position as the image coordinates.