pub fn prewitt_gradients(image: &GrayImage) -> Image<Luma<u16>> {
    gradients_grayscale(
        image,
        kernel::PREWITT_HORIZONTAL_3X3,
        kernel::PREWITT_VERTICAL_3X3,
    )
}
Returns the magnitudes of gradients in an image using Prewitt filters.
src/gradients.rs