Tuesday, January 4, 2011
Hi-Tech Studio: File Format Decoder Ring
The alphabet soup of file extensions is confusing. In this brief article, we show you the differences and similarities of the most common formats.
There seems to be no limit to the number of file formats photographers have to deal with. Presented here are some of the most common image file formats photographers are likely to come across.
Technically, RAW isn’t a file format, but rather a family of individual proprietary file formats. In fact, in some circles you may find heated debate about whether the term should be presented as an acronym—which it isn’t—or simply as the word “raw.” My take is that it should be presented as all caps so it appears in a similar way as other file formats.
A RAW file contains the information gathered by an image sensor at the time of capture and, of course, some related metadata about that capture. In many cases, the information contained in a RAW file is compressed in a lossless way, helping to reduce file size. Some Nikon cameras also offer the option to capture in a lossy compressed RAW file, which means some quality is lost in order to minimize file size.
Because RAW files contain information gathered from the image sensor rather than actual pixel values, these files must be processed before they can be put to use by many digital imaging software tools.
Various RAW Formats
CR2. Canon digital cameras with RAW capture record images in the CR2 file format (earlier digital cameras utilized the prior CRW version of this file format, and some even used a variation on the TIFF file format). The Canon RAW file format contains considerable information about the data gathered by the image sensor, including proprietary information (which is encrypted) related to special features of Canon’s image sensor technology. As a result, certain benefits can be achieved by converting Canon RAW captures using Canon’s Digital Photo Professional software.
NEF. Nikon digital cameras with support for RAW capture utilize the Nikon Electronic Format (NEF) file to store the data gathered by the image sensor, along with a variety of metadata related to the capture. One of the unique features of the NEF file format is that it offers both lossy and lossless compression. These options enable you to balance the desire to maximize the number of captures you can record on a given media card with the overall quality of the final image. Certain RAW capture details are encrypted in the NEF file format so the benefit of that information only can be achieved using Nikon’s Capture NX software.
ORF. The Olympus Raw Format (ORF) is the file format for RAW capture on Olympus digital cameras. This RAW file format is relatively straightforward, in that it contains the data gathered by the image sensor during capture. ORF files can be converted from RAW to actual image file formats with most RAW conversion tools.
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