Using Adobe Photoshop CS, Part 2 - Blurring Images
(Page 6 of 12 )
When there are excessive artifacts in your image, you can try applying a Gaussian blur to soften the image, and reduce the effect of the artifacts. Above that, the Gaussian Blur filter can be used for special effects, such as when you want part of an image to appear in soft focus, or even completely out of focus.
Choose Filter, Blur, Gaussian Blur to bring up the dialog, and experiment with different radius values until you achieve the effect you're looking for (see Figure 5.114). This filter can also be helpful when you're trying to clear up moiré patterns that result from scanning photos that have been printed (halftones).
Figure 5.114 Applying a Gaussian blur.
Tip -There are plenty of other blur effects you can apply to achieve special effects, such as motion, radial, and lens blurs.
To blur just a few pixels at a time, you can use the Blur tool. I find it incredibly useful to soften up the edges after I've silhouetted an image.
Sharpening Images
For images that are blurry or out of focus, you can try to sharpen them by choosing Filter, Sharpen, Unsharp Mask. I find that almost every photo that I scan or import requires some level of sharpening-especially images that I will be uploading for viewing on the Web. Sharpening a photo enhances the edges or borders of color, giving a clearer image that seems to have more life to it (see Figure 5.115). You want to be careful not to oversharpen an image, though, because this will introduce visible artifacts (see Figure 5.116).
Figure 5.115 Applying the Unsharp Mask filter.
Tip -I was always taught to consider the line screen at which the image will be printing to best determine the radius setting for Unsharp Mask. For a 133-line screen, set your radius to 1.3 pixels. A 200-line screen would get a 2.0 radius setting, and so on. Of course, line screens apply only to images that will be used for print purposes.
Alternatively, you can use the Sharpen tool to touch up small parts of your image interactively.
Tip -I've found that many times, sharpening will enhance not only the faces of people and objects in the photo, but also dust and scratches in the photo, making them visible. After sharpening, you may need to apply the Dust & Scratches filter to clear up those artifacts.
Figure 5.116 Too much sharpening can add unwanted artifacts.
 This chapter is from Adobe Creative Suite, by Mordy Golding (Sams, 2003, ISBN: 0672325918). Check it out at your favorite bookstore today. Buy this book now.
|
Next: Getting Rid of Dust and Scratches >>
More Photoshop Articles
More By Sams Publishing
/ 34 
