Learn in the textbookData Compression Methods and Characteristics
DefinitionRun-length encoding (ランレングス法) is a lossless compression technique that shortens data by replacing each stretch of a repeated value with the value and the number of times it repeats.
ExplanationA stretch of the same value is called a run (ラン), and its length is the run length (ランレングス). Data with long runs, such as an image with wide areas of one color, compresses well, while a sequence whose value changes at every position barely shrinks and can even get longer. Details such as whether a value that appears only once also gets a count are set by each scheme.
AnalogyIt is like writing "6 oranges" on a shopping list instead of "orange, orange, orange…"
Memory hookRun (an unbroken stretch) plus length gives "the length of a run." The name itself tells you what gets recorded.