allow height=0

because someone might just want the residuals

src/plenoptic/simulate/canonical_computations/steerable_pyramid_freq.py

@@ -47,9 +47,10 @@ class SteerablePyramidFreq(nn.Module):
     image_shape : `list or tuple`
         shape of input image
     height : 'auto' or `int`
-        The height of the pyramid. If 'auto', will automatically determine
-        based on the size of `image`. If an int, must be positive and less than
-        log2(min(image_shape[1], image_shape[1]))-2.
+        The height of the pyramid. If 'auto', will automatically determine based on the
+        size of `image`. If an int, must be non-negative and less than
+        log2(min(image_shape[1], image_shape[1]))-2. If height=0, this only returns the
+        residuals.
     order : `int`.
         The Gaussian derivative order used for the steerable filters, in [1,
         15]. Note that to achieve steerability the minimum number of
@@ -135,8 +136,8 @@ def __init__(
             self.num_scales = int(max_ht)
         elif height > max_ht:
             raise ValueError(f"Cannot build pyramid higher than {max_ht:.0f} levels.")
-        elif height < 1:
-            raise ValueError("Height must be a positive int.")
+        elif height < 0:
+            raise ValueError("Height must be a non-negative integer.")
         else:
             self.num_scales = int(height)
 

tests/test_steerable_pyr.py

@@ -407,9 +407,9 @@ def test_scales_arg(self, img, spyr, scales):
 
     @pytest.mark.parametrize("height", range(-1, 8))
     def test_height_values(self, img, height):
-        if height < 1:
+        if height < 0:
             expectation = pytest.raises(
-                ValueError, match="Height must be a positive int"
+                ValueError, match="Height must be a non-negative int"
             )
         elif height > 6:
             expectation = pytest.raises(