MIP-map levels in a texture are usually miniaturized versions of the original image, but for debugging purposes it’s sometimes desirable to distinguish levels from each other. One way of doing this is to tint them with various colours.
To use this functionality in PVRTexToolGUI: open an image with power of two dimensions. MIP-maps should be automatically generated. Go to the Preprocessing dialog (under Edit in the menu) and choose “Colour MIP-maps”. If you click on the various levels in the surface pane on the right you can see the results of this operation.
To generate false colour MIP-maps with the command line PVRTexTool use the -m and -e options together.
PVR files can be used to store volume textures, however such files are not supported in PVRTexTool at this time.