Image Quality:

Gerald C. Holst

An overwhelming majority of image quality discussions center on resolution. The term "resolution" has been in use so long that it is thought to be something fundamental that uniquely determines system performance. Subconsciously, we think that a camera with better resolution will provide better image quality. This is generally true for cameras built to a similar design whose modulation transfer functions are of the same functional form.
In fact, resolution provides valuable information regarding the finest detail that can be discerned. It may be specified by a variety of unrelated metrics such as the optics' Airy disc size, the detector size or the Nyquist frequency associated with the detector pitch. But in making these comparisons, it's important to remember that resolution does not include the effects of system noise, nor is it directly related to sensitivity.