Here are sample crops from an artificially-lit scene at each of the Fuji F480's ISO settings. Next to each of these crops, there is a crop from the Canon Powershot A720 IS at the same ISO setting. Although these are both digital cameras with 8 megapixels sensors, they are not direct competitors because the A720 is not an ultra-compact and has a much larger feature-set.
Images below are all unmodified 100% crops from their respective cameras. The ISO sensitivity was set on the camera but white-balance and exposure were fully-automatic, not that there is a choice on the Fuji F480. The A720 was left to its default settings.
These crops help determine which ISO settings can be acceptably used on these cameras. As noise increases, most cameras compensate with noise reduction which introduces softness. The result is that, while you can partly reduce noise at the expense of details, the maximum acceptable print size gets smaller as ISO is increased. The point at which a print become unacceptably noisy is a matter of personal taste.
Take a look at these images and then scroll down to our conclusion which is based on hundreds of images taken with the Fuji Finepix F480, including the ones from which these crops were taken.
Fuji Finepix F480
Canon Powershot A720 IS
ISO 100 - 1/4s F4.4
ISO 100 - 1/4s F4.5
ISO 200 - 1/8s F4.4
ISO 200 - 1/8s F4.5
ISO 400 - 1/17s F4.4
ISO 400 - 1/15s F4.5
ISO 800 - 1/34s F4.4
ISO 800 - 1/30s F4.5
ISO 1600 - 1/60s F4.5
These images show many differences between the two cameras. Colors are obviously different, with the Canon A720 showing colors which are closer to reality. The F480, being more consumer-oriented, exaggerates the red channel to produce a more vivid but less realistic image. Exposure is very similar, with both cameras choosing the same shutter-speed and a nearly identical apertures (F4.4 vs F4.5). Although exposures are similar, the F480 produces a brighter image, which suggests that the F480 is more sensitive to light. In other words. In other words, these two cameras have different interpretation of ISO sensitivities.
With regards to ISO performance, we can clearly see that both the Fuji and the Canon have to balance noise and detail at each ISO setting. As expected, both cameras produced sharp an clean ISO 100 images. At ISO 200, noise is still very subtle but the images became a tad softer, showing that noise-reduction is already kicking in. As we get to ISO 400, images from both cameras become noticeably more noisy and softer. This trend continues into ISO 800, and into ISO 1600 for the A720. The main difference here is that Fuji appears to be applying stronger noise-reduction which produces less noisy but softer images. We would say that until ISO 400, both cameras can pull-off a good mid-size print (12"x9"). ISO 800 is noisy enough that noise is visible on all but small print sizes, say 4"x5 1/3".