ECW not showing in Supported Raster file format list.
In the Registry check if the
HKEY_LOCAL_MACHINE\SOFTWARE\Bentley\AdditionalImageFileFormats
entry exists. It should contain entries for ECWSpecs Class, J2KSpecs Class, and MrSidSpecs Class.
This may be located in the following entry for more recent releases
HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Bentley\AdditionalImageFileFormats