adj.resulting in reduction of data, often via compressionBailey 2006, 175Data compression, however, often affects the nature and format of the archival record, particularly if the compression is a “lossy” rather than a “lossless” process.Bailey 2006, 175, fn. 42“Lossy” compression techniques result in the loss of some of the data. Example formats resulting from this type of compression technique are the Moving Picture Experts Group (MPEG) and Joint Photographic Experts Group (JPEG) formats. “Lossless” compression techniques are those in which no data is lost. Examples of lossless formats include PKZIP, Tagged Image File Format (TIFF), and Graphics Interchange Format (GIF).Bushey 2008, 134Another major difference between RAW and JPEG is the use of compression algorithms; RAW can utilize lossless data compression (i.e., original data is compressed and decompressed as exact, identical data) and JPEG utilizes lossy-data compression (i.e., original data is compressed and then decompressed, permanently removing image information.)Bushey 2008, 135As stated earlier, the drawback to the format is its use of lossy compression, which enables the file to be transmitted quickly and viewed online, but leads to problems for long-term preservation.DPC 2015Lossy Compression A mechanism for reducing file sizes that typically discards data.Cocciolo 2017, 15With digital archiving, the concept of archiving the original or highest resolution copy of an object as the master is common practice. Lower resolution copies, or copies that may make use of lossy compression (compression that discards information that the algorithm developer thinks the viewer will not notice), are generally thought to be acceptable for researcher access but should not be considered archival masters. With digital still images, the practice of creating a digital master as well as an access copy is considered best practice. For example, many libraries, archives, and museums create uncompressed TIFs as their master files and use JPGs for access.Leventhal, Collins, and Walsh 2021, 292–293Unlike AutoCAD’s more fully featured native DWG (drawing) file format, the specifications for Autodesk’s DXF (drawing exchange format) are openly published, making it another CAD exchange format, albeit a lossy one, with support for a much more limited range of potential CAD file data than STEP.Fallon, Leventhal, and Vowell 2022, 80Lossy compression reduces file size at the expense of some amount of information in the file. In the case of an image file, this means that it will be impossible to restore the image to its original resolution.
