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 diseases in which substances called porphyrins build up, affecting the skin or nervous system. The types that affect the nervous system are also known as acute porphyria. Symptoms of acute porphyria include abdominal pain, chest pain, vomiting, confusion, constipation, fever, and seizures. These symptoms typically come and go with attacks that last for days to weeks. Attacks may be triggered by alcohol, smoking, stress, or certain medications.