Clean copy of ImageUtils. [1212]

Since we’re holding off on upgrading to the latest Unidata code the
only way to get Tommy’s fix is to essentially back port the change.

This override can be removed once we’re ready to pull in the latest IDV
code.

This is from
https://github.com/Unidata/IDV/commit/46e3aa30805eb7b040d45a6e47a094b7fa
05089e