The Truth About Photographic File Formats

Questions have arisen on genealogical websites about which format to use for archival purposes of important pictures.

RAW

A camera raw image file contains minimally processed data from the image sensor of either a digital camera, image scanner, or motion picture film scanner. Raw files are named so because they are not yet processed and therefore are not ready to be printed or edited with a bitmap graphics editor. They require special processing programs to edit such as Adobe Photoshop Lightroom, Corel Aftershot Pro or Apple Aperture. The major problem is that no two camera makers use the same “RAW” format.

TIFF – Tag Image File Format

(.TIF file extension, pronounced Tif) TIFF is the format of choice for archiving important images. TIFF is THE leading commercial and professional image standard. TIFF is the most universal and most widely supported format across all platforms.

GIF format is limited to 256 colors and is a lossless compression file format, a common choice for use on the Web. GIF is a good choice for storing line drawings, text, and iconic graphics at a small file size.

PNG format is a lossless compression file format, which makes it a common choice for use on the Web. PNG is a good choice for storing line drawings, text, and iconic graphics at a small file size.

JPG format is a lossy compressed file format. This makes it useful for storing photographs at a smaller size than a BMP. JPG is a common choice for use on the Web because it is compressed. For storing line drawings, text, and iconic graphics at a smaller file size, GIF or PNG are better choices because they are loss-less.

The common theme of most of these is to save space on hard drives. I.E. smaller file sizes which means less “information”

In reverse order, JPEG (JPG) is “good” for direct saving of PERFECT images. It is the default format for digital cameras and scanners. It has 8 bits for grey (256 shades) and 8 bits for red, green and blue (256 each) This is 16 million colors.

PNG is good for graphics and line art. This has 16 million colors as well.

GIF is further limited to 8 bits for color (256 total colors). No longer commonly used.

The last two are loss less. TIFF and RAW. Preferred for archival purposes.

When your camera saves a digital photo as a RAW or TIFF file (if it can), the photo includes all of the information captured by your camera’s image sensor. High end cameras are required to be able to get TIFF or RAW recordings. RAW is “better” because it can be stored very quickly. A TIFF file can take 50 seconds to fully record to the memory card. If you want “archival” files, take the picture in RAW then save directly to TIFF (IF your photo editing program can process RAW formats).

JPEG has another problem. There are choices about how MUCH information is “removed” in compression. A TIFF/RAW file that is 3.8 MB becomes a jpg of 1.3 MB on low compression and 0.7 MB on high compression. That is a loss of 66% of the information for a low compression and a whopping 82% for high compression.

“Converting” back up does no good. The information is long gone.

 
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