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.
1 Porphyria is a group of diseases that are due to the deficiency of one of the enzymes needed to make an important substance in the body called heme. 2  Porphyrias are often classified as acute or cutaneous. 3  Acute types of porphyria affect the nervous system, whereas cutaneous types mainly affect the skin.ach type of porphyria is due to the deficiency of one of the enzymes needed to make a substance in the body called heme. Enzymes are proteins that help chemical reactions happen in the body. Making heme involves a series of eight different enzymes, each acting in turn.