3. Choose a Compression Level
Notice under "Enhancement" in this window from Corel PhotoPaint the "Compression Bar." One other choice is that of "Progressive." This is to allow the picture to download in several passes so that the viewer doesn't have to wait for the best quality of the image to appear before seeing the image. When this is checked and the image posted, the web page viewer does not have to wait so long to decide if she/he wants to see more.
Here is another program, Adobe's PhotoShop Elements:
Under the File main menu, there is an option "Save for Web..." that is followed up by a wizard with recommendations and a readout on the time it will take a viewer to download the image at the compression levels and connection type used.)
Sliding the marker on the small file - to large file slider bar (default is full quality, least compression) reduces file size but also reduces the quality of the image.
One other program - Fireworks by Adobe - will contain all the above plus a jpeg mask option. This allows the editor to preserve the quality of essential parts of the picture while reducing severely the quality of the non-essentials (e.g. background). This gives the web editor another way to balance quality and file size.
Fireworks also is able to be integrated into Adobe's DreamWeaver to "Optimize" images on-the-fly." In Dreamweaver you would right-click on the embedded images such as those above and then right click "Optimize" in the popup window. The resulting screen allows the web page editor to choose lower qualities and preview then apply them to get the least file size at the least loss of quality.