conv – Convolution

Note

Two similar implementation exists for conv2d: theano.tensor.signal.conv.conv2d and theano.tensor.nnet.conv.conv2d. The foremer implements a traditional 2D convolution, while the latter implements the convolutional layers present in convolutional neural networks (where filters are 3D and pool over several input channels).

Platforms: Unix, Windows

theano.tensor.signal.conv.conv2d(input, filters, image_shape=None, filter_shape=None, border_mode='valid', subsample=(1, 1), **kargs)

signal.conv.conv2d performs a basic 2D convolution of the input with the given filters. The input parameter can be a single 2D image or a 3D tensor, containing a set of images. Similarly, filters can be a single 2D filter or a 3D tensor, corresponding to a set of 2D filters.

Shape parameters are optional and will result in faster execution.

Parameters:

• input (dmatrix of dtensor3) – symbolic variable for images to be filtered
• filters (dmatrix of dtensor3) – symbolic variable containing filter values
• border_mode – ‘valid’ or ‘full’. see scipy.signal.convolve2d
• subsample – factor by which to subsample output
• image_shape (tuple of length 2 or 3) – ([number images,] image height, image width)
• filter_shape (tuple of length 2 or 3) – ([number filters,] filter height, filter width)
• kwargs – see theano.tensor.nnet.conv.conv2d

Return type:

symbolic 2D,3D or 4D tensor

Returns:

tensor of filtered images, with shape ([number images,] [number filters,] image height, image width)

conv.fft(*todo)

[James has some code for this, but hasn’t gotten it into the source tree yet.]