diff options
Diffstat (limited to 'docs/examples/tutorial/numpy/convolve_py.py')
-rw-r--r-- | docs/examples/tutorial/numpy/convolve_py.py | 86 |
1 files changed, 43 insertions, 43 deletions
diff --git a/docs/examples/tutorial/numpy/convolve_py.py b/docs/examples/tutorial/numpy/convolve_py.py index c3cbc5f86..39b276a04 100644 --- a/docs/examples/tutorial/numpy/convolve_py.py +++ b/docs/examples/tutorial/numpy/convolve_py.py @@ -1,43 +1,43 @@ -import numpy as np
-
-
-def naive_convolve(f, g):
- # f is an image and is indexed by (v, w)
- # g is a filter kernel and is indexed by (s, t),
- # it needs odd dimensions
- # h is the output image and is indexed by (x, y),
- # it is not cropped
- if g.shape[0] % 2 != 1 or g.shape[1] % 2 != 1:
- raise ValueError("Only odd dimensions on filter supported")
- # smid and tmid are number of pixels between the center pixel
- # and the edge, ie for a 5x5 filter they will be 2.
- #
- # The output size is calculated by adding smid, tmid to each
- # side of the dimensions of the input image.
- vmax = f.shape[0]
- wmax = f.shape[1]
- smax = g.shape[0]
- tmax = g.shape[1]
- smid = smax // 2
- tmid = tmax // 2
- xmax = vmax + 2 * smid
- ymax = wmax + 2 * tmid
- # Allocate result image.
- h = np.zeros([xmax, ymax], dtype=f.dtype)
- # Do convolution
- for x in range(xmax):
- for y in range(ymax):
- # Calculate pixel value for h at (x,y). Sum one component
- # for each pixel (s, t) of the filter g.
- s_from = max(smid - x, -smid)
- s_to = min((xmax - x) - smid, smid + 1)
- t_from = max(tmid - y, -tmid)
- t_to = min((ymax - y) - tmid, tmid + 1)
- value = 0
- for s in range(s_from, s_to):
- for t in range(t_from, t_to):
- v = x - smid + s
- w = y - tmid + t
- value += g[smid - s, tmid - t] * f[v, w]
- h[x, y] = value
- return h
+import numpy as np + + +def naive_convolve(f, g): + # f is an image and is indexed by (v, w) + # g is a filter kernel and is indexed by (s, t), + # it needs odd dimensions + # h is the output image and is indexed by (x, y), + # it is not cropped + if g.shape[0] % 2 != 1 or g.shape[1] % 2 != 1: + raise ValueError("Only odd dimensions on filter supported") + # smid and tmid are number of pixels between the center pixel + # and the edge, ie for a 5x5 filter they will be 2. + # + # The output size is calculated by adding smid, tmid to each + # side of the dimensions of the input image. + vmax = f.shape[0] + wmax = f.shape[1] + smax = g.shape[0] + tmax = g.shape[1] + smid = smax // 2 + tmid = tmax // 2 + xmax = vmax + 2 * smid + ymax = wmax + 2 * tmid + # Allocate result image. + h = np.zeros([xmax, ymax], dtype=f.dtype) + # Do convolution + for x in range(xmax): + for y in range(ymax): + # Calculate pixel value for h at (x,y). Sum one component + # for each pixel (s, t) of the filter g. + s_from = max(smid - x, -smid) + s_to = min((xmax - x) - smid, smid + 1) + t_from = max(tmid - y, -tmid) + t_to = min((ymax - y) - tmid, tmid + 1) + value = 0 + for s in range(s_from, s_to): + for t in range(t_from, t_to): + v = x - smid + s + w = y - tmid + t + value += g[smid - s, tmid - t] * f[v, w] + h[x, y] = value + return h |