# Examples from pyvista.ImageDataFilters.erode
# ============================================

# Create a toy example with two non-zero grayscale foreground regions
# using `pad_image()`.
import pyvista as pv
# Create an initial background point
im = pv.ImageData(dimensions=(1, 1, 1))
im['data'] = [0]
# Add a foreground region
im = im.pad_image(pad_value=255, pad_size=(4, 3), dimensionality=2)
# Add a second foreground region
im = im.pad_image(pad_value=128, pad_size=(2, 0, 1, 0))
# Add background values to two sides
im = im.pad_image(pad_value=0, pad_size=(1, 0))

# Define a custom plotter to plot pixels as cells.
def image_plotter(image):
    pl = pv.Plotter()
    pl.add_mesh(
        image.points_to_cells(),
        cmap='grey',
        clim=[0, 255],
        show_scalar_bar=False,
        show_edges=True,
        lighting=False,
        line_width=3,
    )
    pl.camera_position = 'xy'
    pl.camera.tight()
    pl.enable_anti_aliasing()
    return pl

# Show the image.
image_plotter(im).show()

# Erode it with default settings. Observe that both foreground values are eroded.
eroded = im.erode()
image_plotter(eroded).show()

# Use a larger kernel size.
eroded = im.erode(kernel_size=5)
image_plotter(eroded).show()

# Use an asymmetric kernel.
eroded = im.erode(kernel_size=(2, 4, 1))
image_plotter(eroded).show()

# Use binary erosion. By default, the max value (`255` in this example) is eroded
# with the min value (`0` in this example). All other values are unaffected.
eroded = im.erode(binary=True)
image_plotter(eroded).show()

# Equivalently, set the binary values for the erosion explicitly.
eroded = im.erode(binary=[0, 255])
image_plotter(eroded).show()

# Use binary erosion with the other foreground value instead.
eroded = im.erode(binary=[0, 128])
image_plotter(eroded).show()

# ----------------------------------------------------------------------
# Generated by sphinx-examples-as-code https://github.com/pyvista/sphinx-examples-as-code