Learn in the textbookFile Formats for Still Images and Documents
DefinitionJPEG is a still-image format that uses lossy compression (非可逆圧縮) to store color-rich images such as photos in small files by throwing away information the eye hardly notices.
ExplanationA method that lets compressed data be restored exactly to the original is called lossless compression, while one that cannot restore it but shrinks the data much further is called lossy compression. JPEG belongs to the second group and handles full color of about 16.77 million colors, so it is widely used for digital camera and web photos. On text or sharp-edged graphics, however, blurring and blocky noise tend to appear around the edges.
AnalogyIt is like squeezing your travel luggage into a vacuum bag and pulling out things you probably will not need along the way. The bag gets lighter, but what you took out is gone for good.
Memory hookThe name is the initials of the standards group Joint Photographic Experts Group, and the word Photographic points straight at what it does best.