*** GUI-based HighView
personal use free of charge since 10/2011 ***
Image fusion is a concept of combining multiple images into composite products, through which more information than that of individual input images can be revealed.
Figure 1: Image pan-sharpening with QuickBird images. The left and middle input images are obtained from DigitalGlobe, and the right-hand image is the fused result from HighView. All images are subject to the same histogram stretch.
|Figure 2: Image pan-sharpening with IKONOS images. The left and middle input images are obtained from Space Imaging, and the right-hand image is the fused result from HighView.|
The past few decades have seen quite a few image fusion and pan-sharpening methods in the public domain, including those based on multi-resolution wavelet transforms, PCA (Principal Component Analysis) transforms, and IHS (Intensity-Hue-Saturation) transforms. These methods, however, largely disregard important spectral characteristics of specific satellite sensors, therefore no consistent, colour-preserving results can be achieved. In other words, a simple data-driven approach without referring to spectral evidence can hardly produce satisfactory outcomes. This becomes more apparent when the recent generation of high- and medium-resolution satellite images is available, where there are marked spectral disparities between colour bands and the panchromatic band.
For more information
on spectral features and curves of recent satellite
sensors, please refer to websites of major image
www.digitalglobe.com (QuickBird, WorldView-2)
www.geoeye.com (IKONOS, GeoEye-1)
physical evidence of spectral characteristics and
applies optimisation methods to perform ideal image
pan-sharpening. While the fused imagery at a finer
spatial resolution still retains the mean of the
coarse-resolution input, its standard deviation
should naturally become larger due to
increased details and heterogeneity of image
features at finer resolutions (Figure 3). These
important characteristics set HighView apart
from other pan-sharpening methods on the market that
incorrectly claim the preservation of standard
deviation of the fused imagery at a finer
Figure 3: Statistical changes from
coarser-resolution input to fused,
finer-resolution imagery in HighView.
All Pléiades, WorldView-1, QuickBird, GeoEye-2, IKONOS, SPOT-5 and Landsat ETM+ images used at GeoSage website are demonstration, sample, or free images from Astrium, DigitalGlobe, Space Imaging, SPOT Image, NASA, USGS, GeoGratis and GLCF. The following banner picture is created by http://wordle.net/