Absolute Beginner's Guide to Digital Photography

By applying the correct amount of blur, you can remove these unwanted patterns

and still retain some sharpness in the image. Follow these steps to apply the

Gaussian Blur filter to a scanned image with moiré or halftone screen patterns:

1. After scanning an image, save it with a new name as a TIFF file.


2. Make sure you are viewing the image at 50% or 100%. Zoom in (View, Zoom
   In) if you aren’t viewing it at one of these resolutions. Moiré patterns can
   develop when viewing at other resolutions.


3. Choose Filter, Blur, Gaussian Blur (see Figure 13.8). Click the Preview check
   box in the dialog box if it isn’t already checked.

198 ABSOLUTE BEGINNER’S GUIDE TODIGITAL PHOTOGRAPHY

FIGURE 13.8

Gaussian Blur.

4. Drag the slider bar or enter a number to see the effect on the image. Try 1.0,
   then 2.0, and 3.0 to start and see what value removes the halftone dot pat-
   tern but retains some sharpness in the image.


5. Click OK to close the dialog box and view the blur. You can always undo the
   change by choosing Edit, Undo or pressing Ctrl+Z (xZ for Mac users).

Using Blur to Add an Artistic Touch

Some images weren’t meant to be “tack sharp.” Artistic images for example, might

look better out of focus or with a small amount of blur added, such as in Figure

13.9, for example.

This image looks more appropriate for its use as a Christmas card after some

Gaussian Blur has been added (see Figure 13.10). In this case, a value of 1.0 was

applied, then green and blue highlights were reduced using Image, Adjustments,

Color Balance.