jpeg image

JPEG: The term actually stands for "Joint Photographic Experts Group," because that is the name of the committee that developed the format. But you don't have to remember that because even computer nerds will think you're weird if you mention what JPEG stands for. Instead, remember that a JPEG is a compressed image file format. JPEG images are not limited to a certain amount of color. Therefore, the JPEG format is best for compressing photographic images. So if you see a large, colorful image on the Web, it is most likely a JPEG file. While JPEG images can contain colorful, high-resolution image data, it is a lossy format, which means some quality is lost when the image is compressed. If the image is compressed too much, the graphics become noticeably "blocky" and some of the detail is lost.


gif image

GIF: short for Graphics Interchange Format is a file format for storing graphical images up to 256 colors. It uses LZW compression which is a lossless compression method. Until the year 2004, this was covered by a patent owned by Unisys and the reason why the PNG file graphic format was invented.

There are two versions of GIF both created by Compuserve. The earlier GIF 87a and the enhanced 89a which stored multiple images (thus allowing animation), and interlacing.

GIF files are probably the most popular on the web being used in logos and any color images with 256 or fewer colors. For images containing text GIF tends to be better than JPG because the files tend to be smaller and JPG files usually have some degree of compression and this can make text blurry.


png image

PNG: (pronounced ping as in ping-pong; for Portable Network Graphics) is a file format for image compression that, in time, is expected to replace the Graphics Interchange Format (GIF) that is widely used on today's Internet. Owned by Unisys, the GIF format and its usage in image-handling software involves licensing or other legal considerations. (Web users can make, view, and send GIF files freely but they can't develop software that builds them without an arrangement with Unisys.) The PNG format, on the other hand, was developed by an Internet committee expressly to be patent-free. It provides a number of improvements over the GIF format.
Like a GIF, a PNG file is compressed in lossless fashion (meaning all image information is restored when the file is decompressed during viewing). A PNG file is not intended to replace the JPEG format, which is "lossy" but lets the creator make a trade-off between file size and image quality when the image is compressed. Typically, an image in a PNG file can be 10 to 30% more compressed than in a GIF format.