Output Options; Optimizing And Displaying On The Web Page 2

To size images for e-mail or the web, I suggest keeping the image size to 800x600 or smaller. The main reasons for this are speed of display, and file size. A secondary concern, especially with images posted on a website, is protection--bigger images are more attractive to someone wanting to use it for other purposes. Most image-editing applications have a re-size feature. In Photoshop Elements, it's Image>Resize>Image Size. Leave the Constrain Proportions box checked and enter the critical dimension--either Width or Height. Be sure the Resample Image check box is not checked--all you want to set are the dimensions.

Sharpening should be the last step performed before saving your image to avoid over sharpening.

Sharpening And Saving
Sharpening an image should be the last step performed before saving and will be different for each intended use. Sharpening an image is usually known as Unsharp Masking. It works by increasing the contrast along the edges of objects in the image. By emphasizing the contrast on the edges, the image appears to be sharper with finer details.

In Elements, select Filter>Sharpen> Unsharp Mask. The three slider controls work together with Amount controlling how strongly the edge contrast is increased, Radius determines how wide the enhancement will be. Too much and the image will have halos--obvious highlights around the edges of objects. Radius is the most important setting, so keep a close eye on the preview as you make adjustments. Threshold determines how much contrast there needs to be between objects to be considered an edge. Higher numbers require more contrast. There isn't one setting for Unsharp Mask that works for every image, but I find that web images are usually in the area of 100-150 percent Amount, .7-1.5 Radius, and 2-6 Threshold.

Save For Web is a great way to see what the effect of compression settings are. Using my normal quality setting of 70, I can detect no obvious difference in image quality, yet the file size shrinks from 731KB down to 75KB!

The final step is to save the image. Here, the goal is to keep file size to a minimum and the quality as high as possible. Normally, I save my web images with a JPEG setting of 7 or 70 (same setting, different scale). The Save For Web feature in Photoshop and Photoshop Elements is a great way to experiment with compression settings. Select File>Save For web, making sure that
JPEG is selected as the file type, and adjust the quality setting to an acceptable amount.

As always, I'm interested in your feedback and questions. If you have questions on this, or other digital output issues, send me e-mail at jon@joncanfield.com. I'll try to respond to all questions, and we'll answer some of the most common questions here in the column.