Raster TAB files are used to store control points, a coordinate system, and user attributes.
Most raster format readers will read TAB files present alongside a dataset, and most raster format writers have an option to generate a TAB file to accompany the output dataset. Consult individual format documentation for more information on their TAB file support.
The control points represent georeferencing information for the raster. When reading this information, FME will attempt to determine if these control points represent the extents of the raster (that is, they occur at the corners of the raster) or if they are Ground Control Points (GCPs), and apply this information accordingly. Note that georeferencing information will be discarded for datasets that contain multiple subdatasets, as there is no way to determine which subdataset the information corresponds to.
Attributes are not natively a part of raster TAB files. However, FME will read and write attributes to raster TAB files in the same manner as is done for vector TAB files. This enables the storage of user attributes for many formats that don’t otherwise support attribution.
Information in TAB files will be given more precedence than information in the raster dataset. For example, if the TAB file stores georeferencing information that is different than that from the source dataset, it is the TAB file georeferencing that will be applied to the raster. If this is not desired, a simple workaround is simply to move or rename the TAB file so it will not be read by the format reader. Additionally, note that readers that read both world and TAB files will give more precedence to the world file.