There are a lot of post here and elsewhere of people who want to show previews of PDFs and images rather than the generic program icons of the viewer programs. There are a lot of posts of people who don't want to show the previews and only want to show the program icons.

I want to know if there's some way I can choose which extensions show previews, say only JPG and GIF files, while leaving other files, like PDFs showing the generic program icon.

I know the File View options setting (Always show icons, never thumbnails), but that's an all or nothing option. I want to choose which extensions show thumbnails. (Specifically, just want generic PDF icon for those files, rather than first page preview, but want the previews for photos.) Thanks for your help and suggestions.