Classic Methods¶

Classic pansharpening methods use signal processing techniques without requiring training data.

Brovey Transform¶

The Brovey transform is a component substitution method that uses band ratios:

from methods.classic import brovey

fused = brovey(pan, ms)

Algorithm: $$MS_{sharp}^i = MS^i \times \frac{PAN}{\sum_j MS^j}$$

Intensity-Hue-Saturation transformation:

from methods.classic import ihs

fused = ihs(pan, ms)

Process: 1. Convert MS to IHS color space 2. Replace Intensity with PAN 3. Convert back to RGB

Smoothing Filter-based Intensity Modulation:

from methods.classic import sfim

fused = sfim(pan, ms)

Algorithm: $$MS_{sharp}^i = MS^i \times \frac{PAN}{PAN_{lowpass}}$$

Gram-Schmidt spectral sharpening:

from methods.classic import gram_schmidt

fused = gram_schmidt(pan, ms)

Injects high-frequency details from PAN into MS:

from methods.classic import hpf

fused = hpf(pan, ms)

Algorithm: $$MS_{sharp}^i = MS^i + w \times (PAN - PAN_{lowpass})$$

Method	Spectral Quality	Spatial Quality	Speed
Brovey	Medium	High	Fast
IHS	Medium	High	Fast
SFIM	High	Medium	Fast
Gram-Schmidt	High	High	Medium
HPF	Medium	High	Fast