janeO,

A very good program for processing out noise in photographs is called Noise Ninja. It runs on Mac/Mac Intel, Linux, and the legacy operating system Windows. The program can run standalone, or as a plug-in to Photoshop.

You can learn more from their website:
www.picturecode.com/

I use this program a lot for low-light photos. Generally these are of belly dancers in club, restaurant, festival, or theatrical lighting that is dim. I've also had success using it for astrophotography. It does a very good job naively, that is without any input. However, as described on the website and in user documentation, there are things you can do to improve the results beyond the default case. This involves giving the program input about the type of imaging sensor that your camera contains, and at various ISO levels. These "noise filter" files can be easily created by the user, though many are supplied for a variety of existing cameras. It might be possible that your camera is already covered. However, the default case is still quite good.

For people in studio or live shots, what Noise Ninja tends to do is create significantly more uniform background colors for darker tones. For example, a black background goes deep black, with residual chroma noise being virtually eliminated. On skin tones, it makes the skin look less "splotchy" than the photo appears right out of the camera. The edge definition of eyes, mouths, eyebrows, and hair are significantly improved. I've found this program even improves well-exposed photos taken at low ISO on a DSLR; the content just pops after Noise Ninja processing. But the program has compelling results for noisier high-ISO DSLR images.

For astrophotography, Noise Ninja does quite well with long exposure noise, beyond that which the camera does by subtracting out the "dark slide" for your particular camera. This application seems more analogous to yours, with IR photography. The program is also useful for scanned film or transparencies, and can certainly work with monochrome images.

I use Noise Ninja standalone on a MacBook, as well as two Linux server computers.

Hope this is helpful information, and I wish you well.

Blessings and Light,
Michael