chainer.functions.space2depth¶

chainer.functions.space2depth(X, r)[source]¶

Computes the space2depth transformation for subpixel calculations.

Parameters:	X (`Variable` or `numpy.ndarray` or `cupy.ndarray`) – Variable holding a 4d array of shape `(batch, channel, dim1 * r, dim2 * r)`. r (int) – the downscaling factor.
Returns:	A variable holding the downscaled layer array from subpixel array sampling. The shape is `(batch, channel * r * r, dim1, dim2)`.
Return type:	Variable

Note

This can be used to compute inverse super-resolution transformations. See https://arxiv.org/abs/1609.05158 for details.

See also

depth2space()

Example

>>> X = np.arange(24).reshape(1, 1, 4, 6).astype('f')
>>> X.shape
(1, 1, 4, 6)
>>> X
array([[[[  0.,   1.,   2.,   3.,   4.,   5.],
         [  6.,   7.,   8.,   9.,  10.,  11.],
         [ 12.,  13.,  14.,  15.,  16.,  17.],
         [ 18.,  19.,  20.,  21.,  22.,  23.]]]], dtype=float32)
>>> y = F.space2depth(X, 2)
>>> y.shape
(1, 4, 2, 3)
>>> y.data
array([[[[  0.,   2.,   4.],
         [ 12.,  14.,  16.]],

        [[  1.,   3.,   5.],
         [ 13.,  15.,  17.]],

        [[  6.,   8.,  10.],
         [ 18.,  20.,  22.]],

        [[  7.,   9.,  11.],
         [ 19.,  21.,  23.]]]], dtype=float32)