from matplotlib import pyplot as plt
from pylinac.core.image_generator import AS1200Image
from pylinac.core.image_generator.layers import FilteredFieldLayer, GaussianFilterLayer

as1200 = AS1200Image()  # this will set the pixel size and shape automatically
as1200.add_layer(FilteredFieldLayer(field_size_mm=(30, 30), cax_offset_mm=(20, 40)))
as1200.add_layer(GaussianFilterLayer(sigma_mm=3))
# plot the generated image
plt.imshow(as1200.image)