At ISO 100 the P7100 produces sharp, clean images free from noise.
Raing sensitivity to ISO 200 poses no problems for the P7100.
At ISO 400 the P7100 is still producing noise-free images.
By ISO 800 there is a hint of softening as the camera's built-in noise-reduction algorithms kick in.
By ISO 1600 fine detail has started to crumble, especially in the mid-tones and shadow areas.
ISO 3200 is both soft and noisy.
Unless you're shooting thumbnail-sized images for online use ISO 6400 is all but unusable.