A Use Case is a real photographic scenario that describes the requirements for a camera or a lens to shoot a certain type of photograph. DxOMark defines 3 Use Cases for sensors : Portrait, Landscape and Sports, and a general purpose use case to report sensor overall performance. Read more about Sensor Use Cases definitions.
Too low exposure, resulting in a dark photo.
The fundamental quality characterizing a photon, equivalent to its energy. Differing visible wavelengths are perceived as different colors.