Make sure you don’t miss a single Photofocus post – point your feed reader to the free Photofocus RSS Feed here and subscribe.
While most of you know what JPEGS are all about, remember that every day someone new joins the digital photo revolution so today, I’m answering a question I get all the time believe it or not – “What is a JPEG?”
JPEG (Joint Photographic Experts Group) is a file compression scheme that stores digital photographs using a lossy compression routine.
Most photographers deal with JPEGS either coming out of a digital camera or in iPhoto/Photoshop/Aperture/Lightroom, etc., when making images web or computer ready. Unfortunately, as described above, JPEGS are a lossy form of compression. This means that the heavier the compression, the more the image is degraded. If you compress detailed images, you get more loss than if you compress soft images. Remember that once you have saved an image as a JPEG, you have compressed it. You are compounding the degradation to the image if you open it, modify it in any way, and save it again. This can create poor results, so the best practice is to make changes to an image while it is in a lossless state such as a PSD or TIF file, and only save an image as a JPEG once.
Most labs and online solutions use JPEGS. While they are a lossy compression method, they still produce outstanding results. JPEGs can be larger and render more color than other file formats – such as GIFs (limited to 256 colors.)
A JPEGS strong point is its ability to save continuous tone better than GIF files, while significantly reducing file size, which is why most Web photo renderings are saved as JPEGS.