On K-7 and noise reduction (NR), there are a number of importants threads/discussons including these:
[1]
https://www.pentaxforums.com/forums/pentax-dslr-discussion/106600-k-7-high-iso-success.html
[2]
https://www.pentaxforums.com/forums/pentax-dslr-discussion/117808-k7-iso-2500...ing-tests.html
In the thread [1], Kittycat46 explained clearly that there are 3 basic NR techniques:
"
a) Shoot RAW, then process with Noise Reduction later b) JPEG straight out of camera with NR "Off", then process with Noise Reduction software. It sounds counter-intuitive, but NR software like Noise Ninja and Noiseware work best with image files which have not had any previous NR processing done on it. c) JPEG straight out of camera with "Strong" NR - as you found. The K-7's detail retention is quite good up to ISO3200, even with Strong NR."
The 3rd technique (c) is the one proposed by Adam in [1].
Personnally, I prefer the 2nd option (b) since shoot mostly in JPEG. I have NR Off and I post-process (PP) the photographs with Noiseware. My choice is linked partly with my regular usage of continuous shooting, for which it is best to kill off in-camera PP including High ISO correction, and the good performances and reasonable price of Noiseware. (It is free basically.)
Koenig, in the thread [2], presented a nice comparison of differnet NR PP techniques. It is worth to read the thread and the various posts.
Overall, a few conclusions:
- Pentax Digital Camera Utility (PDCU) is not bad for some simple (everyday) NR with low ISO
- For high ISO NR, use some dedicated softwares like Noiseware or NoiseNinja. (The post of Koenig [2] is a worthwhile comparison also of NR softwares.)
- On the K-7, most Pentaxians recommend a maximum ISO setting of ISO 3200.