The JPEG (Joint Photographic Experts Group) image format enjoys widespread use on the Internet due to its ability to display many colors while maintaining a relatively small file size. For storing and transmitting photographs and digital images on the Internet JPEG is superior to GIF, which only supports 256 colors. Its small image size also makes JPEG far more practical than PNG, which produces images with a much larger file size. The downside to it is that JPEG uses a "lossy" compression method, which causes noticeable damage to image quality. This includes:
-"Mosquito noise"‚ commonly found around edges, such as eyes;
-Square-shaped noise distortion known as "blockiness" or "checkerboarding";
-Fuzziness and loss of edge clarity.
All JPEGs will show signs of this damage to some degree - almost no web images are free of JPEG artifacts. If the complete image is to be usable in any way, it's important to remove this compression artifact noise quickly and effectively. The problem is that typical noise reduction algorithms are useless for removing this special kind of noise caused by lossy compression methods.
Photoshop does include a JPEG compression artifact remover, but the native Photoshop algorithm usually does not do a good job with JPEG mosquito noise, discoloration, or fuzziness, although it does help reduce checkerboarding to some degree. And, of course, it doesn't help you if you don't have Photoshop. To access it, go to Filters->Noise->Remove Noise... and check "JPEG Artifacts."
A more often-used solution is a free little JPEG removal tool called Topaz DeJPEG. It's a plug-in that works with both Photoshop and Irfanview (which is freeware). Find it at www.topazlabs.com .
As an Irfanview plug-in, Topaz DeJPEG is easy to quickly apply to any and all downloaded images to give an instant and noticeable quality boost. Photoshop users also find it invaluable to make downloaded images instantly more usable.
Very simple way to make downloaded images look better.
