If you're saving a file that's destined for the Internet, you can use the Save for Web & Devices command (newly tweaked for Photoshop CS4 — see Figure 7.3) to output your file in one of the Web-friendly formats.
The JPEG, GIF, and PNG formats are available via the Save or Save As commands, but using Save for Web & Devices offers more intuitive access to various useful options for saving files for the Web.
Compare your original and optimized images side-by-side. View your original file and simultaneously compare it to as many as three alternate versions, using different combinations of compression schemes and file format options.
Preview file sizes and download times. The Save for Web & Devices dialog box displays the effect of the different file formats and their compression options on the final file size of your image. You can also view the estimated download times at different Internet connection speeds — from low-bandwidth, dial-up connections to corporate T1 connections.
Set the color profile used by your image. Use this option to output the file with the document's color profile, or convert it to the standard sRGB Web color space. Learn more about color profiles in Chapter 23.
Resize the Web version of your image. Want to create a smaller version of your image specifically for use on the Web? Instead of duplicating the file, then resizing it by using the Image Size command, and saving that file by using one of the Web formats, simply enter ...