Alan Freedman -- The Computer Language Company - Computer Desktop Encyclopedia
Computer Desktop Encyclopedia
Longest-Running Tech Reference on the Planet

A CDE Definition

You'll love The Computer Desktop Encyclopedia (CDE) for Tech Term of the Day (TTOD)

LOOK UP ANOTHER TERM


lossy file compression

See lossy compression.



lossy compression

A compression technique that does not decompress digital data back to 100% of the original. Lossy methods can provide high degrees of compression and result in smaller compressed files, but some number of the original pixels, sound waves or video frames are removed forever. Examples are the widely used JPEG image, MPEG video and MP3 audio formats.

The greater the compression, the smaller the file. However, a high image compression loss can be observed in photos printed very large, and people with excellent hearing can notice a huge difference between MP3 music and high-resolution audio files (see audiophile). Typically, the moving frames of video can tolerate a greater loss of pixels than still images.

Lossy compression is never used for business data and text, which demand a perfect restoration (see lossless compression). See data compression, codec examples, JPEG, MPEG and MP3.




Lossless Vs. Lossy Compression
Business data requires lossless compression, while audio and video applications can tolerate some loss, which may not be very noticeable.








Sometimes Hard to Tell
The top JPEG image is one fifth the file size of the bottom image, which was compressed the least. Look carefully at the orange section on the top of this cake.










Easier to See With Text
The top JPEG image was compressed the most, and the text is not as sharp as the least compressed. The bottom blow-up shows the distortion clearly.








Lossless GIFs Are Better for Text
The same text is saved in the lossless GIF format. Not only is it as sharp as the least-compressed JPEG, the GIF file is almost 1/10th the size.






Personal Use Only

Before/After Your Search Term
BeforeAfter
LORAN-Blost cluster
LORAN-Clost packet
LORAN-DLoT
LoRaWANLotus
LOSLotus 1-2-3
losslessLotus menu
lossless codecLotus Notes
lossless compressionLotus Notes Visual Programmer
lossyLotus Script
lossy compressionLotus SmartSuite

Terms By Topic
Click any of the following categories for a list of fundamental terms.
Computer Words You Gotta KnowSystem design
Job categoriesUnix/Linux
Interesting stuffPersonal computers
InternetIndustrial Automation/Process Control
Communications & networkingAssociations/Standards organizations
HistoryDesktop publishing
Audio/VideoGraphics
MainframesSecurity
ProgrammingHealthcare IT
System design