Figure Properties - SERC

filter2
2filter2
Purpose Two-dimensional digital filtering
Syntax Y = filter2(h,X)
Y = filter2(h,X,shape)
Description Y = filter2(h,X) filters the data in X with the two-dimensional FIR filter in
the matrix h. It computes the result, Y, using two-dimensional correlation, and
returns the central part of the correlation that is the same size as X.
2-828
Y = filter2(h,X,shape) returns the part of Y specified by the shape
parameter. shape is a string with one of these values:
Remarks Two-dimensional correlation is equivalent to two-dimensional convolution
with the filter matrix rotated 180 degrees. See the Algorithm section for more
information about how filter2 performs linear filtering.
Algorithm Given a matrix X and a two-dimensional FIR filter h, filter2 rotates your filter
matrix 180 degrees to create a convolution kernel. It then calls conv2, the
two-dimensional convolution function, to implement the filtering operation.
See Also conv2, filter
'full' Returns the full two-dimensional correlation. In this case, Y is
larger than X.
'same' (default) Returns the central part of the correlation. In this
case, Y is the same size as X.
'valid' Returns only those parts of the correlation that are computed
without zero-padded edges. In this case, Y is smaller than X.
filter2 uses conv2 to compute the full two-dimensional convolution of the FIR
filter with the input matrix. By default, filter2 then extracts the central part
of the convolution that is the same size as the input matrix, and returns this as
the result. If the shape parameter specifies an alternate part of the convolution
for the result, filter2 returns the appropriate part.