kdu_kernels::get_energy_gain

Computes the energy gain factor associated with the one dimensional synthesis basis vectors (sequences) for samples in the low- or high-pass subband at a particular DWT level.

The function does not explicitly compute the analysis or synthesis vectors for more than a certain number of DWT levels, beyond which point it relies upon the fact that the vectors converge to samplings of underlying continuous wavelet and scaling functions. This allows a large number of DWT levels to be specified without consuming inordinate amounts of memory calculating the kernels. For an explanation of these convergence properties, see Section 17.3 of the book by Taubman and Marcellin.

To determine the energy gain for 2D subbands, the 1D energy gains for each direction may be multiplied.

The energy gain factor.

which [kdu_kernel_type]

level_idx [int]