GRASS logo


i.fusion.hpf - Fusing high resolution panchromatic and low resolution multi-spectral data based on the High-Pass Filter Addition technique (Gangkofner, 2008).


imagery, fusion, sharpening, high pass filter, HPFA


i.fusion.hpf --help
i.fusion.hpf [-l2c] pan=filename msx=filename(s)[,filename(s),...] suffix=suffix string [ratio=rational number] [center=string] [center2=string] [modulation=string] [modulation2=string] [trim=rational number] [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Linearly match histogram of Pan-sharpened output to Multi-Spectral input
2-Pass Processing (recommended) for large resolution ratio (>=5.5)
Match color table of Pan-Sharpened output to Multi-Spectral input
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


pan=filename [required]
High resolution Panchromatic image
msx=filename(s)[,filename(s),...] [required]
Low resolution Multi-Spectral image(s)
suffix=suffix string [required]
Suffix for output image(s)
Names of Pan-Sharpened image(s) will end with this suffix
Default: .hpf
ratio=rational number
Custom ratio
Custom ratio overriding standard calculation
Options: 1.0-10.0
Center cell value
Center cell value of the High-Pass-Filter
Options: low, mid, high
Default: low
2nd Pass center cell value
Center cell value for the second High-Pass-Filter (use -2 flag)
Options: low, mid, high
Default: low
Modulation level
Modulation level weighting the HPF image determining crispness
Options: min, mid, max
Default: mid
2nd Pass modulation level (use -2 flag)
Modulation level weighting the second HPF image determining crispness (use -2 flag)
Options: min, mid, max
Default: mid
min: Minimum: 0.25
mid: Mid: 0.35
max: Maximum: 0.5
trim=rational number
Trimming factor
Trim output border pixels by a factor of the pixel size of the low resolution image. A factor of 1.0 may suffice.

Table of contents


i.fusion.hpf is an implementation of the High Pass Filter Additive (HPFA) Fusion Technique. It combines high-resolution panchromatic data with lower resolution multispectral data, resulting in an output with both excellent detail and a realistic representation of original multispectral scene colors. The process involves a convolution using a High Pass Filter (HPF) on the high resolution data, then combining this with the lower resolution multispectral data. Optionally, a linear histogram matching technique is performed in a way that matches the resulting Pan-Sharpened image to the statistical mean and standard deviation of the original multi-spectral image.


  1. Computing ratio of low (Multi-Spectral) to high (Panchromatic) resolutions
  2. High Pass Filtering the Panchromatic Image
  3. Resampling MSX image to the higher resolution
  4. Adding weighted High-Pass-Filetred image to the upsampled MSX image
  5. Optionally, matching histogram of Pansharpened image to the one of the original MSX image
+                                                                            +
| Pan Img ->  High Pass Filter  ->  HP Img                                   |
|                                      |                                     |
|                                      v                                     |
| MSx Img ->  Weighting Factors ->  Weighted HP Img                          |
|       |                              |                                     |
|       |                              v                                     |
|       +------------------------>  Addition to MSx Img  =>  Fused MSx Image |

Source: Gangkofner, 2008



The module is fairly easy to use. Arbitrary examples: Pansharpening of one band:
i.fusion.hpf pan=Panchromatic msx=Red

Pansharpening of multiple bands:

i.fusion.hpf pan=Panchromatic msx=Red,Green,Blue,NIR

Various illustrated examples detailed in the document i.fusion.hpf, implementation of the High Pass Filter Additive (HPFA) Image Fusion Technique (PDF)






Nikos Alexandris
Panagiotis Mavrogiorgos


Available at: i.fusion.hpf source code (history)

Main index | Imagery index | Topics index | Keywords index | Graphical index | Full index

© 2003-2020 GRASS Development Team, GRASS GIS 7.8.3dev Reference Manual