The problem with digital noise is still acute. Even expensive professional cameras produce noise at high ISO settings. Not to mention consumer-level cameras that perform well only at ISO 50–100.
Most digital cameras offer the option of automatic ISO setting (auto). In this case, a camera chooses settings on its own basing on the shooting conditions. As a result, one can easily get "noisy" photos because the camera can decide to shoot at a high ISO value.
A fragment of the picture in real size is shown below.
The following photo was taken in automatic mode. Some photos from the same session were taken at ISO 400, others at 261 or 236. But the result is the same – all of them are very noisy. We will take one such photo and try to improve it.
The added complication is that the photo was then saved in JPEG. This compression is responsible for the JPEG artifacts.