Module spectral 

CCSDS 122.1-B-1 Spectral Preprocessing Transform for Multispectral and Hyperspectral Image Compression. CCSDS 122.1-B-1 Spectral Preprocessing Transform.

Provides spectral decorrelation for multispectral and hyperspectral images before 2D compression (CCSDS 122.0).

The pipeline is: Input → Upshift → Spectral Transform → Downshift → 2D Encoder

Three spectral transforms are defined:

• Identity (passthrough)
• IWT (Integer Wavelet Transform, CDF 5/3, 5 levels)
• POT (Pairwise Orthogonal Transform, approximates KLT)

The IWT is applied independently along the spectral axis (z) for each spatial pixel (x, y).

Enums

SpectralTransform

Spectral transform selection.

Constants

IWT_LEVELS

Number of IWT decomposition levels (Section 4.4.4).

Functions

downshift

Downshift: multiply each sample by 2^-d, rounding to nearest integer (Section 3.2.3, Eq. 13).

inverse_transform_spectral

Apply the inverse spectral transform along the z-axis.

iwt_forward_5

Five-level forward IWT decomposition (Section 4.4.4).

iwt_forward_single

Single-level forward IWT decomposition (CDF 5/3 lifting).

iwt_inverse_5

Five-level inverse IWT decomposition (Section 4.4.4.2).

iwt_inverse_single

Single-level inverse IWT decomposition (Section 4.4.3.2, Eq. 25-26).

transform_spectral

Apply the spectral transform along the z-axis for a 3D image.

upshift

Upshift: multiply each sample by 2^u (Section 3.2.2, Eq. 11).