What Does JPEG Mean and How Does .JPG Compress Images?
.jpg comes from JPEG, which is short for "joint photographic experts group". They are the organization who wrote what is now the standard means of compressing images. The .jpeg compress technique works by exploiting the fact the human eye doesn't notice small changes in picture quality. .jpeg's compress picture files, (ie: make them smaller), by reducing differences between colors, for example, in such a way that it's hardly noticeable. Programmers describe this as "lossy". In other words part of the picture is lost. There are other ways of compressing images without using .jpg compress but they do not reduce the file size to the same extent.
What Do You Lose in Quality If You Use .JPG to Compress Images?
If you use the .jpeg compress technique then you undoubtedly end up with a different image than the one you started out with. However, in most cases this is barely noticeable. It's designed for use with photographs or anything that depicts what you might call the "real world" and, in this field, it has become by far the dominant file type. The .jpeg compress technique doesn't work quite so well if you want to reproduce line drawings or cartoons, for example. The only time a problem might arise with the .jpeg compress technique is if the resulting image needs to be scanned by a machine. A machine may be confused by small differences that are invisible to the naked eye.
What are the Advantages of Using .JPG to Compress Images?
There are numerous advantages to using the .jpeg compress technique for images. .jpeg compress, for example, can be used to reduce files to a size that is small enough to be viewed in an email. Depending on whether you value image quality or file size the degree of compression with .jpeg compress can be varied considerably. JPEG is also the industry standard for file compression and the file-ending .jpeg is instantly recognizable to everybody and recognizable as an image rather than another kind of file.