convolution neutral networks is a hot spot in machine learning technique.
But is that convolution the same as the following convolution?
let us start with 1D signal.
function h can be called mask.
correlation
linear system
obviously, gradient operator is a linear system.
an example of non-linear system
shift invariant
so, convolution defines a linear and shift-invariant system.
the equations above show that there are two formats of convolution formula.
h(t) or h[n] can be called filter or mask.
I will show u some useful filters.
Box function
when a is near to 0, we have Dirac Function.
its area is always equal to 1.
Dirac Function has some properties.
Firstly, we talk about absorption property.
what happens when the input to an Linear Shift Invariant system is an Dirac Function?
Dirac description of sampling
review complex number.
atan2 (-pi, pi]
Fourier shift
sampling： convert analog time or space to digital
matlab functions
fftshif
fft decomposes any periodic function or periodic signal into the sum of a (possibly infinite) set of simple oscillating functions, namely sines and cosines (or, equivalently, complex exponentials).
low pass filter
