Occurrence
The Image is not listed in the selectable Images list, or when you attempt to load messages indicating 'Unsupported file format type'.
Solution
Certain image file types are not support by certain tools, such as Rectify Images does not support ECW files. Also within a file type of TIF, there are many variations and some variations such as BigTIF (>2GB) or tiled TIF files are not supported. Unfortunately there is no way to tell if it is a supported format. All you can do is attempt to open it.
You can use 3rd party freeware such as Ifranview to open unsupported formats and save as a supported format such as JPG or PNG.
