Whether you’re designing an image destined for life on the Web or creating an email-friendly version of a digital photo, you need to perform three very specific steps to create a high-quality image that people can download quickly. Consider the following a basic overview of the process; you’ll learn detailed info about each step later in this section:
Adjust the image’s dimensions.
First, you need to decide how big the image should be. In some cases, someone else may give you the size (like when you’re hired to create a web banner or an ad). Other times, you choose the size (like when you email a digital photo, send a sample design to a client, or post an image in an online discussion forum). Once you know the size you need, you can use the Image Size dialog box (The Mighty Image Size Dialog Box) to resize it, provided your image is already the correct aspect ratio. If your image needs a little pruning around the edges, grab the Crop tool and then choose “W x H x Resolution” from the Option bar’s aspect-ratio-and-crop-size menu (Cropping to a Specific Shape, Size, and Resolution). Next, enter your desired dimensions in the width and height fields and be sure to include the unit of measurement, such as 800 px. You can either leave the resolution field blank or enter 72. (For more on resizing with the Crop tool, see Chapter 7.)
Decide which file format you want to use.
The most common choices are JPEG, PNG, and GIF. See Choosing the Best File Format ...