Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Dither is routinely used in processing of both digital audio and digital video data, and is often one of the last stages of audio production to compact disc.
Hepatic porphyria. Hepatic porphyrias is a form of porphyria in which the enzyme deficiency occurs in the liver. Examples include (in order of synthesis pathway): Acute intermittent porphyria. Porphyria cutanea tarda and Hepatoerythropoietic porphyria.
Porphyria is a group of disorders that can cause nerve or skin problems. A porphyria that affects the skin is called cutaneous porphyria. A porphyria that affects the nervous system is called acute porphyria. The most common type of porphyria is porphyria cutanea tarda (PCT), which affects the skin.