Optimise your images to prepare them for your web site. Optimising is preparing them to look good while loading as quickly as possible.
Optimisation is used to prepare images for your web site. This is necessary so that the site/page/graphic loads quickly, visitors to your site will not wait for things to load. Other media, eg movies and music also need to be optimised for the same reason, though people might expect to wait a bit longer for these.
Optimising includes reducing the number of pixels or colours in an image. It is not the same as reducing the apparent size in mm or inches. The amount of reduction will depend on the quality you need to present an image on a page. Some work to illustrate a page might be reduced a lot but photographs or artwork for sale might have to show more detail and so take longer to load.
Make sure you keep your originals as well as your optimised versions.
To see the physical size you want an image to be on a page you can insert an unoptimised image temporarily, drag its size to what you want and then note the dimensions in the Properties Inspector bar. Do not leave it in this state. It is the file size not the image size that determines how long your image takes to load. Optimising is done to reduce the file size.
Some usual file formats for images:
gif: (Graphics Interchange Format) A gif is usually ideal for cartoons, logos, graphics with transparent areas and animations.
jpeg: (Joint Photographic Experts Group) was developed for photographic or high-colour images. This format is best for photographs, images using textures or gradient colour transitions and anyl images that require more than 256 colours.
png: file format for Fireworks
Below are short outline instructions for optimising your images. For more details see Fireworks and Photoshop Help
Optimise in Fireworks
Open your image. Choose Modify → Canvas → Image Size. Complete the menu box.
Go to 2-Up or 4-Up and in Optimise section. On the right, choose PNG or JPEG (photo) or GIF (simple graphic) and set colours and quality. Check in the 2 or 4-Up windows (click into one to select it) to see the quality as you alter the file size in pixels. You can see the file size and estimated loading time change at the bottom of each window.
Use File → Export to send the optimised image to your DW files.
Optimise in Photoshop
Open your image. Choose Image → Image Size. Complete the menu box.
Choose File → Save for Web. Here you have 2-Up and 4-Up tabs and, on the right, a panel to change the file kind and the quality.
Click Save when you are ready and save in the appropriate application or folder.
page updated 27/5/10