The image below is of a TIFF file, but not just any TIFF. Hidden inside are coordinates that bind the image to a specific place on Earth. For every pixel in the image, an estimated latitude and longitude can be calculated, making it a powerful source for computational analysis and spatial visualization. This file is a GeoTIFF, a format widely used by the geospatial community for creating and sharing image-based data—particularly satellite imagery, aerial photography imagery, and raster datasets. It’s also used for digitized historical maps. GeoTIFFs are a special subtype of TIFFs, built with everything a TIFF file is required to contain plus a bonus section of hidden geospatial data that can be used to link the image to a particular space within a particular coordinate system.
At first glance, GeoTIFFs can appear indistinguishable from standard TIFF files. Their filenames end in the “.tif” file extension, just like any other TIFF. They can be opened and viewed in any application that opens TIFF files. Once opened in a standard TIFF image viewer, however, they can sometimes appear stretched (as seen above), rotated, or warped in more complex ways. The complexity of the warping depends on the type of calculation used during the original georeferencing of the image.