How do I prepare image files for display on a web page?
Files should be prepared in one of two modes, Grayscale or RGB (Red, Green, Blue–these are the colors of light a monitor uses to display an image. The black in an on-screen image is an area in which the monitor provides no light.) An image file should be 72dpi (Dots Per Inch) the size you want it to appear on-screen. The file format to use is JPEG. Mac users: Make sure the file has the .jpg filename extension, or it won’t be readable in a web browser or on a PC.