Learn in the textbookData Compression Methods and Characteristics
DefinitionThe compression ratio (圧縮率) is a value that shows how well compression works, found by dividing the data size after compression by the size before.
ExplanationThe value is written as a ratio or a percentage, and the smaller it is, the more the data has shrunk. Count the data size in the same unit before and after compression, whether that unit is bits, bytes, or characters.
AnalogyIf a duvet in a vacuum storage bag shrinks to one third of its original thickness, that one third is the compression ratio.
Memory hookRead it as the share of what is left. The less that remains, the better the compression worked.