Compressed
From The Glossary of Digital Photography
What is done to data when storing images so that they take up less storage space. Certain image formats, such as JPEGs, are compressed formats; other formats, such as TIFFs, are not compressed. Besides taking up less storage space, compressed files take less time to transfer between computers or to download from the Web. There are two types of compressed image file formats: lossy and lossless. Lossy compressed images achieve their compression by throwing away data, while lossless do not. See compression
