Most people tend not to think about the details of their online photo sharing experience. As long as their photos get from their computers to their online photo album, they could care less about the processes that got it there. The way that digital cameras designed, this really isn't a problem, as most cameras and photo editing software support this approach. However, there's a lot more that goes into online photo sharing than is obvious on the surface.



Those who are interested in the fundamentals of digital photography may be curious about different file formats. Many have heard or seen the terms for picture file extensions, such as .jpg (or JPEG), .gif, .tif, and .png. What do all these different three letter extensions mean?

The term JPEG actually stands for “Joint Photographic Experts Group” – the group that initially created the standard back in 1992. Since then, the JPEG has become the most commonly found picture file type on the Internet. This is primarily because JPEGs offer a tremendous amount of flexibility in terms of its compression and picture quality. That is, its possible to significantly reduce the storage size of a JPEG file by also reducing the quality. Back when the Internet was first starting out, downloading mutli-megabyte picture files just wasn't practical. JPEGs could maintain a reasonable image quality while making the file size of the image much smaller.

JPEGs have remained an Internet standard thanks to this quality. People are able to make images much easier to transfer between computers without losing a significant amount of picture quality. The drawback to JPEGs is that it is a “lossy” format – this means that each time a picture is edited and resaved in the JPEG format, it loses a degree of quality.

TIFF stands for Tagged Image File Format. TIFF files are versatile and high quality, supporting up to 48-bit color depth (compared to 8-bit for GIFs and 24-bit for JPEGs). The downsides of this format are two-fold. For one, TIFF files have a wide variance and an image viewer that can view one type of TIFF file can't necessarily view anther. Secondly, TIFF files are not widely supported by web browsers, making them impractical for online photo sharing.

GIFs and PNGs

GIF stands for Graphics Interchange Format. Like the JPEG, GIF files are also commonly found all around the Internet. GIF files are comparatively limited in their color palette – having only 256 colors to work with. This make GIFs a good choice for relatively simple pictures without a lot of color differences, such as cartoons and simple logos. While it a lossless format that doesn't degrade in quality, it's pretty rare that you'll see a photograph in a GIF format in the modern age, since most cameras are able to take pictures with significantly more color depth.

PNGs, or Portable Network Graphics files, are the successor to GIFs. Unlike GIFs, they support truecolor, a 16-million color palette. PNGs are lossless, making them great for editing photos. Most web browsers support PNGs, but they can still be quite large. In many cases, the best choice is to edit a file in PNG format, then convert to JPEG for distribution.