Mar 1, 2005

File Formats for Digital Imaging

A site called Earthbound Light has a nice article on different formats for digital photos. Newcomers to digital cameras are often perplexed by terms such as JPEG, TIFF, RAW. Worth a read if you want to make sure you're choosing the best format for you.

One of many confusing decisions confronting the new user of a higher-end digital camera is the choice of what file format to use. In order to decide, you'll first need to know a bit about each.

Most every digital camera supports JPEG capture. JPEG stands for the organization that developed the format, the "Joint Photographic Experts Group ." I've written previously about JPEG files and have probably impressed on at least some that they are not a good format for image editing. JPEG is a "lossy" compression algorithm that discards at least some information every time you resave it. It makes a very good capture format though. Since the files are small, you can fit a lot of them on even a modest sized compact flash card. For the same reason, you can also fit more in the camera's internal buffer, meaning you can shoot more images in a row without having to wait for them to be moved to the CF card. And guess what? They take less time to write as well.

With JPEG, the camera applies all the settings you have chosen including sharpening, exposure, white balance, color space and so on. All JPEG images are 8-bits per channel. If you do a good job taking the picture and get it right in camera, all is well, just as it is would be on film. There are better choices though if you want to maximize the potential of your images post-capture. One nice thing about JPEGs though is that they are all but universal in terms of support. You can take the images straight from the camera and use them in a wide variety of applications. Although smaller than other image formats, even jpegs generally have to be downsized some to send by email. A typical JPEG from the Nikon D100 will be between one and three megabytes in size.

If you want to do any editing of your images, it's best to resave them in a format other than JPEG after downloading them to your computer. This way, you get the benefit of small file sizes when it counts in camera, but don't have to live with the image degradation inherent in the jpeg format when you edit them later.
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