Why do the Landsat 7 (ETM+) browse images look so different from the Landsat 4-5 (TM) images?
Even though the band combination is the same, differences in the browse processing will make the final images look very different between the two sensors. Landsat 4-5 (TM) scenes have been subsampled to a much lower resolution (480 meteres), with a standardized stretch applied. Landsat 7 images are resampled to 240 meters, and each image has a customized stretch applied based on individual scene content. The Landsat 4-5 TM images will also be approximately 1/4 the size, but the actual data will cover approximately the same area as a Landsat 7 ETM+ image. In spite of these differences between the browse images, data from the two sensor types should be fairly comparable in data content, resolution, and scene size.
