db2 is called as Daubechies extremal phase wavelets. The number refers to the number of vanishing moments.
[a,d] = db2(x)
A vector representing a 1-d discrete signal whose samples are integers.
A vector representing the approximation part of the integer transform.
A vector representing the detail part of the integer transform.
It computes the approximation and detail integer parts for a 1-d integer signal using db2 integer wavelet transform. The lengths of the approximation and detail parts is equal to the ceiling of the half of length of the input signal.