Function Reference
— Function File: y = filter2 (b, x)
— Function File: y = filter2 (b, x, shape)

Apply the 2-D FIR filter b to x. If the argument shape is specified, return an array of the desired shape. Possible values are:

'full'
pad x with zeros on all sides before filtering.
'same'
unpadded x (default)
'valid'
trim x after filtering so edge effects are no included.

Note this is just a variation on convolution, with the parameters reversed and b rotated 180 degrees.

See also: conv2