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 named from the ancient Greek word porphura, meaning purple.Porphyrins are precursors of heme, a part of the hemoglobin molecule. Heme is manufactured in a multistep process. Defects of enzymes needed at various steps of heme synthesis result in distinct clinical syndromes known as porphyrias.