Optimizing Images for the Web

Choosing the Correct Image File Type

GIF: Graphics Interchange Format

Use for:
Images with solid blocks of color
Simple images and line drawings
Animated images

Not recommended for:
Photographs
Images with a great deal of color gradient


JPEG: Joint Photographic Experts Group

Use for:
Photographs
Images with a great deal of color gradient

Not recommended for:
Simple images with large blocks of color

JPG files are usually larger than a GIF file because they are capable of displaying millions of colors as opposed to a GIF’s 256 colors. A JPEG image can be compressed to reduce file size. When an image is compressed, pieces of the image are removed from the file. Using an image editing program, try compressing files at several different percentage points to find the most favorable balance between quality and file size.


Reducing Image File Size

Resizing Images: While you canresize the images on your by dragging the corner of the image, the file size doesn’t actually change, but only displays smaller. You can reduce the image file size by resizing the image in a graphic editing program and saving the smaller file size.

Interlacing – When there is no way to avoid a large file size you can save a GIF or JPG file as an interlaced file. An interlaced image will gradually fade from a blurred image to a sharp image as the page loads. Saving as an interlaced photo increases the file size, but the overall image loads quickly and gives the perception of a faster download time.