The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
Figure 1. Comparison of the visual quality of the four testing images under the same display conditions (the images are enlarged 2 
times to show details) 
To prove that the four images have the same quality, the 
individual bands of each of the four testing images are also 
compared through overplaying the same band of different 
images in one image under the same stretching condition, but 
displayed using different colours (Figure 2). If there is any 
difference between corresponding bands of the images, the 
overlaid image will appear colour in the areas where differences 
exist. Otherwise, the overlaid bands will appear as a grey 
image, as if only one band were displayed. A close check of the 
images in Figure 2 shows that no colour appears in any of the 
images, which proves that the four images have the same 
quality when individual bands are compared.