Why lossy compression is preferred

Lossy compression is sometimes preferred because multimedia data is meant for human eyes and ears, which cannot detect every detail. Removing the undetectable detail gives much smaller data with little visible loss in quality.

Justification

1. Much higher compression. Lossless methods give about 2:1 for photos; JPEG gives 10:1 to 20:1 with good quality, and MPEG gives 50:1 or more for video. Raw video at about 184 Mbps would be impossible to stream or store without it.
2. Limited bandwidth and storage. Internet streaming, mobile networks, video calls and digital TV need data rates that only lossy coding can reach.
3. Human perception limits. The eye is less sensitive to colour than brightness and to fine high-frequency detail; the ear cannot hear sounds masked by louder ones. These parts can be removed unnoticed.
4. Adjustable quality. The user can trade quality for size (for example, the JPEG quality factor or MP3 bit rate).
5. Real-time use. Faster transmission makes live conferencing and broadcasting practical.

Example: a 5 MB photo saved as JPEG at 85% quality may be 500 KB, and viewers see almost no difference.

Lossless compression is still preferred for text, code and medical images where exactness is vital.