I created two simple image diff/merge utilities like WinMerge.
1. One is written using Win32 API (non-MFC) and FreeImage library.
This can be used as a library like frhed.
My winmerge-v2 fork already uses it.
I think it can be integrated with winmerge-v2 and winmerge 2011.
If you are interested in the feature, I will write a patch to integrate it.
2. Another one is written using Qt framework
I hope this help WinMerge development.