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Image Processing

Levels of Processing

The following levels of processing are available to the general public for Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images:

• Level 0R (raw uncorrected)
• Level 1R (reformatted)
• Level 1G (radiometrically and geometrically corrected)

• Level 1Gt (systematically terrain corrected)
• Level 1T (terrain corrected)
• Level 1T SLC-off Segment-based Gap-fill

This page provides further explanation of each level of correction.

Comparison of LPGS and NLAPS

Two separate processing systems are used to generate USGS Landsat 7 Level 1 products: the Level 1 Product Generation System (LPGS) and the National Land Archive Production System (NLAPS). The products generated by LPGS and NLAPS are similar in most ways, but there are significant differences. This page compares the two processing systems and their products.

MTFC Parameters

The new Modulation Transfer Function Compensation (MTFC) parameters for the Landsat 7 Calibration Parameter File (CPF) were submitted for inclusion in the October, 2001 CPF release. The new coefficients used in the CPF were derived from on-orbit estimates of the ETM+ along- and across-scan MTF. They replace the previous coefficients, which were based on pre-launch MTF measurements only in the along-scan direction.