How to remove or disable "Finder Preview" for a file type?

I have some large .hdr files which are large image files, and cause PathFinder (but I guess the issue is not really Finder or PathFinder but the preview app being called in Preview feature) to beachball forever. The problem is the calculation of image size and thumbnail display when either clicking on the .hdr image file (which brings in preview) or ctrl-clicking on the file which kicks off image size calculation for contextual menu in PathFinder (confirmed by PathFinder support). While I can get around ctrl-clicking until this issue is fixed, there is no walking around preview feature for thumbnail viewing unless I tell Preview not to consider .hdr files as image files (while still being able to view thumbnails of other image formats such as jpg and tif, which is what I will like to do).

Those .hdr files are not valid Photoshop radiance files. They are generated by Photomatix (www.hdrsoft.com). So, Preview seems to be having issues with it. Whenever I click on a large file (no problem with an empty file labeled with .hdr extension), PathFinder memory shoots from 50+MB to 500+MB and it beachballs forever until I kill it.

So, I will like to tell Preview not to consider .hdr files as image files. Pointers on how to do this will be appreciated. I am guessing that Preview.app is being called by Finder (same thing should apply to PathFinder) to calculate image sizes and render thumbnails. Please correct me if I am wrong about it.