C = conv2(___,shape) returns
a subsection of the convolution according to shape.
For example, C = conv2(A,B,'same') returns the
central part of the convolution, which is the same size as A.
In applications such as image processing, it can be useful to compare the input of a convolution directly to the output. The conv2 function allows you to control the size of the output.
Create a 3-by-3 random matrix A and a 4-by-4 random matrix B. Compute the full convolution of A and B, which is a 6-by-6 matrix.
The Sobel edge-finding operation uses a 2-D convolution to detect edges in images and other 2-D data.
Create and plot a 2-D pedestal with interior height equal to one.
A = zeros(10);
A(3:7,3:7) = ones(5);
mesh(A)
Convolve the rows of A with the vector u, and then convolve the rows of the result with the vector v. The convolution extracts the horizontal edges of the pedestal.
u = [1 0 -1]';
v = [1 2 1];
Ch = conv2(u,v,A);
mesh(Ch)
To extract the vertical edges of the pedestal, reverse the order of convolution with u and v.
Cv = conv2(v,u,A);
mesh(Cv)
Compute and plot the combined edges of the pedestal.
2-D convolution, returned as a vector or matrix. When A and B are
matrices, then the convolution C = conv2(A,B) has
size size(A)+size(B)-1. When [m,n] = size(A), p
= length(u), and q = length(v), then
the convolution C = conv2(u,v,A) has m+p-1 rows
and n+q-1 columns.
When one or more input arguments to conv2 are
of type single, then the output is of type single.
Otherwise, conv2 converts inputs to type double and
returns type double.
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