Function decompose_2d 

pub fn decompose_2d(
    signal_2d: ArrayViewMut2<'_, f32>,
    buffer: ArrayViewMut1<'_, f32>,
    wavelet: Wavelet<'_>,
)

Forward wavelet transform, 2D, only twice, inplace.

+-----------+    +-----+-----+
|           |    |  A  |  H  |
| 2D Signal | => +-----+-----+
|           |    |  V  |  D  |
+-----------+    +-----+-----+

Horizontal firstly, then vertical.

Hard requirements

• buffer_size >= signal_side_length + window_size - TWO