Fine-Tuning Your Digital Photos for the Web

If your company operates a Web site or you maintain a personal Web site, you can easily place pictures from your digital camera onto your Web pages.

If you want your Web site to be one that people love to visit, take care when adding photos (and other graphics, for that matter). Too many images or images that are too big quickly turn off viewers, especially viewers with slow dialup connections. Every second that people have to wait for a picture to download brings them a second closer to giving up and moving on from your site.

To make sure that you attract, not irritate, visitors to your Web site, keep this information in mind:

• For business Web sites, make sure that every image you add is necessary. Don't junk up your page with lots of pretty pictures that do nothing to convey the message of your Web page — in other words, images that are pure decoration. These kinds of images waste the viewer's time and cause people to click away from your site in frustration.

• If you use a picture as a hyperlink, also provide a text-based link. (A hyperlink, in case you're new to the Internet, is a graphic or bit of text that you click to travel to another Web page.) This suggestion applies whether you use a single image as a link or combine several images into a multi-link graphic, or image map. Why the need for both image and text links? Because many people with slow Internet connections set their browsers so that images do not automatically download. Images appear as tiny icons that the viewer can click to display the entire image. This setup reduces the time required for a Web page to load. But without those text links, people can't navigate your site unless they take the time to load each image.

• Save Web-bound photos in the JPEG file format. This format produces the best-looking on-screen pictures, and all Web browsers can display JPEG (pronounced jay-peg) files. Two other newer photo formats, PNG (pronounced ping) and JPEG 2000, are not fully supported by either browsers or Web-page creation programs yet.

• Don't save photos in the GIF format. If you're familiar with Web design, you may be wondering about using the GIF format for your online photos. GIF is a great format for small graphics, such as logos. But it's not good for photos because a GIF image can contain only 256 colors. As a result, photos can turn splotchy when saved to this format, as illustrated by Figure 1.

• Understand how pixel count affects display size. To accommodate the widest range of viewers, size your images with respect to a screen display of 640 x 480 pixels. Don't forget that the Web browser or email program needs part of the available screen space. For email pictures, use a maximum image width of 400 pixels and a maximum height of 300 pixels.

Note that with this low pixel count, people can't make a decent print from your pictures. Consider using a photo-sharing Web site instead of email if you want people to have the option of printing your photos.

• File size determines how long it takes other people to download your pictures. It also determines how long you sit and wait for pictures to make it from your computer to the Web.

• Pixel count, not ppi, determines file size. File size is determined by the total number of pixels in the image, not the output resolution (pixels per inch, or ppi). The file size of a 640 x 480-pixel image is the same at 72 ppi as it is at 300 ppi.

• Increasing the amount of JPEG compression is another way to reduce file size. This option creates smaller file sizes by dumping some image data, which can reduce picture quality.

If you want to control the use of your photos, think twice about posting them online. Remember, anyone who visits your page can download, save, edit, print, and distribute your image — without your knowledge or approval. To prevent unauthorized use of your pictures, you may want to investigate digital watermarking and copyright protection services.

To start learning about such products, visit the Web site of one of the leading providers, Digimarc. The Web site operated by the Professional Photographers of America provides good background information on copyright issues in general.