Add missing 0th layer of laplacian pyramid

skimage/transform/pyramids.py

@@ -262,6 +262,7 @@ def build_laplacian_pyramid(image, max_layer=-1, downscale=2, sigma=None,
     cols = image.shape[1]
 
     prev_layer_image = image - _smooth(image, sigma, mode, cval)
+    yield prev_layer_image
 
     # build downsampled images until max_layer is reached or downsampled image
     # has size of 1 in one direction

skimage/transform/tests/test_pyramids.py

@@ -33,7 +33,6 @@ def test_build_laplacian_pyramid():
     pyramid = build_laplacian_pyramid(image, downscale=2)
 
     for layer, out in enumerate(pyramid):
-        layer += 1
         layer_shape = (rows / 2 ** layer, cols / 2 ** layer, dim)
         assert_array_equal(out.shape, layer_shape)