About optimization

Optimization is the process of fine-tuning the display quality and file size of an image for use on the Web or other online media. Adobe Photoshop and Adobe ImageReady give you an effective range of controls for compressing the file size of an image while optimizing its online display quality.

There are two methods of optimizing images:

• For basic optimization, the Photoshop Save As command lets you save an image as a GIF, JPEG, PNG, or WBMP file. Depending on the file format, you can specify image quality, background transparency or matting, color display, and downloading method. However, any Web features--such as slices, links, animations, and rollovers--that you've added to a file are not preserved.

For complete information on using the Save As command to save an image as a GIF, JPEG, or PNG file, see Saving images.

• For precise optimization, you can use the optimization features in Photoshop or ImageReady to preview optimized images in different file formats and with different file attributes. You can view multiple versions of an image simultaneously and modify optimization settings as you preview the image to select the best combination of settings for your needs. You can also specify transparency and matting, select options to control dithering, and resize the image to specified pixel dimensions or a specified percentage of the original size.

When you save an optimized file using the Save for Web (Photoshop) or Save Optimized (ImageReady) command, you can choose to generate an HTML file for the image. This file contains all the necessary information to display your image in a Web browser.

The Save for Web (Photoshop) or Save Optimized (ImageReady) commands are designed specifically to provide a more robust and intuitive set of options for saving an image file for use on the Web. This includes a refined sensitivity to file size and image color palette that is unavailable from the Save As command. When creating graphics for Web use, the Save for Web / Save Optimized commands are recommended.