The JPEG image format, well known for its association with modern digital cameras and its prolific use on the Internet, has many desirable properties over other image types when size is a concern. Short for “Joint Photographic Experts Group,” the algorithm used in generating and displaying JPEGs is extremely efficient when compared to lossless compression such as PNGs and BMPs. This holds true especially for photographs and other images with smoothly transitioning color gradients, like photographs and picture scans.

However, as it is a lossy compression method, some of the original data is irrecoverably lost once an image is saved. JPEGs can also exhibit a phenomenon known as “artifacting;” for instance, the left side of the example photograph was saved at the highest possible quality, 100%, while the right at just 10%. Notice that much of the color and contrast information is gone on the latter side (especially around the brick floor), and the well-known blocky artifacts associated with low-quality JPEGs appear all over.

About this file: the photo of my friends in costume was taken at Otakon 2007, an annual Japanese animation convention in Baltimore, Maryland. Using The GIMP, I modified both halves of the images to display true JPEG quality differences, then added a red divider line in between.