I am a computer programmer by trade and I noticed the apparent lack (to me at least) of image enhancement software available. I am speaking about software that would use sophisticated techniques such as a Wiener filter to remove motion blur or contrast enhancement. Do these exist for the PC? Camera makers seem intent on increasing pixel count, but have we extracted all of the data in a given digital file?
They do indeed exist, perhaps it’s no coincidence you’re on here looking for them 
The kind of filters you speak of exist in G’MIC - wiener [smooth] and retinex/DCP dehaze would be examples. They more than likely exist in others too.
Most if not all the software on here has at least some advanced filtering, so you came to the right place!
Retinex is available in RawTherapee.
Many thanks. I am a PS CC user, but I just downloaded GIMP and the GMIC plugin. Very impressive. It will take a while for me to see what these are capable of.
I improved my pp a lot by spending time on cambridge in colour where just about all use PS. A number of people on there are extremely capable. What I find is that no single open source package will match PS. The ones I use most often are Rawtherapee, Fotoxx and the GIMP Also HUGIN and Macrofusion Enfuse at times. Fotoxx is purely a Linux application. The maintainer sees it as a photographer’s swiss army knife. It’s a pretty good description of it. For raw I always start with RT.
What you will miss is adjustment layers. The GIMP doesn’t have them and it will take anyone some time to pick up all of the things it’s capable of.
Another package that did specialise in more exotic filters is Photivo. Development seems to have largely stopped.
It seems certain other filters can be used from Linux
https://www.evolware.org/?p=440
I’ve had a bit of a photo lay off and that one is something I intend to look at in more detail.
John