Landsat Missions
Figure 1 shows a section of a Level Zero Reformatted (L0R) image containing a city and airport. The monochrome expanded view at right represents the Band 1 subset showing a 12 × 12 pixel grid centered on the intersection of the two runways at the airport.
Figure 1. DN values for L0R image
If you click on the figure to enlarge it, you will notice the pixel values in Digital Numbers (DN) saved in 8-bit format. This format covers the range from 0 to 255 DN. During L0R processing, no radiometric gains and biases are applied to the data.
Figure 2 shows the same section of the image shown in Figure 1, but extracted from the corresponding Level 1 Radiometrically Corrected (L1R) product. The monochrome expanded view at right shows the Band 1 subset representing the same 12 × 12 pixel grid as used in Figure 1.
Figure 2. DN values for L1R image
If you click on the figure, you will notice how the data are 16-bit values that have been converted to radiance. During L1R processing, various system noise and image artifacts are characterized and corrected. An L1R image has not been resampled, so each pixel is at its most accurate radiance value. This also means, however, that there is NO any geometric or geodetic resampling or alignment of the pixels. Thus, the airport and roads in this sample are misaligned just as they were in the L0R image.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://landsat.usgs.gov
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Page Contact Information: landsat@usgs.gov
Page Last Modified: May 09, 2008
