Using the PANSHARP algorithm

PANSHARP fuses high-resolution panchromatic imagery with multispectral imagery, creating a high-resolution color image. This technique is often referred to as pansharpening. This program was designed to work with 8-bit, 16-bit, or 32-bit real data. Panchromatic data can be fused with multispectral imagery simultaneously acquired by the same sensor or with images from different sensors. The best results are achieved when the imagery is collected simultaneously and the resolutions of the panchromatic and multispectral data are closely matched. The spectral characteristics of the original data will be preserved in the resulting high resolution color imagery; this means that analysis such as classification can be done on the pansharpened imagery with the added benefit of higher spatial resolution.

Note: Landsat 7 panchromatic and multispectral data is co-registered at the satellite; therefore, the geocorrection step is not necessary when using this data.

Ensure the panchromatic (PAN) channel and multispectral (MS) channels are co-registered, geocorrected, or orthorectified.
Open the PAN and MS images.
Open the Algorithm Library, and locate and double-click PANSHARP.
Choose the PAN image channel from the InputPan port. The input reference image channels should be selected so that the MS bands cover the frequency range of the PAN channel as closely as possible. The channel number given in the table below is the standard ordering on the sensor and may differ from the order in an actual data file.
Select the MS channels to use in the Input port. The best pansharpening results are obtained from MS channels whose wavelengths lie within the spectral frequency range of the PAN data.
Send the output to the viewer or save it to a new .pix file.

Note: To avoid reducing the radiometric resolution of the data, process and save all the image bands in signed 16 bits. Testing demonstrated that 16 bits for intermediate data are enough; 32 bits are not necessary.

The following table lists the reference bands for some well-known satellite sensors.

Table 1.
Sensor	Reference Bands
Landsat 7 (ETM+)		Green 2	Red 3	Near IR: 4
SPOT 1, 2, 3 (HRV)		Green 1	Red 2
SPOT 5 (HRG)	Blue 1	Green 2
IRS 1C, 1D		Green 1	Red 2
IKONOS	Blue 1	Green 2	Red 3	Near IR: 4
QuickBird	Blue 1	Green 2	Red 3	Near IR: 4

There is only one optional parameter in the InputParams 1 tab. For a description of the No Data image value parameter, see PANSHARP in the online Help.

The automatic image fusion algorithm was developed by Dr. Yun Zhang from the University of New Brunswick. For more information and comparative results, see the following references:

Zhang, Yun. Problems in the fusion of commercial high-resolution satellite, Landsat 7 images, and initial solutions. ISPRS, Vol. 34, Part 4, Geospatial Theory, Processing and Applications, Ottawa, 2002.
Zhang, Yun. A new automatic approach for effectively fusing Landsat 7 and IKONOS images. IEEE/IGARSS'02, Toronto, Canada, June 24-28, 2002.