I Mapinfo 15.2 or 16.0 64-bit, you have opened a TIF file via File>Open>Raster Image.
When you go to the layer properties to apply a transparency, the Select Color button is disabled.
Solution
This bug in MapInfo Raster hijacking the previous handling of Image files in Mapinfo. This is resolved in Mapinfo 17.0 or later, but requires re-creation of the TAB file.
To manual fix the issue -
1. Close the file in MapInfo. Open the TAB file for the TIF image in notepad
2. Delete the 3 lines -
RasterStyle 4 1
RasterStyle 7 0
RasterStyle 9 1
3. Save and re-open it. You will now be able to apply a transparency.
