Photoshop® CS4 All-in-One For Dummies®

Chapter 1. Making Corrections with Daily Filters

In This Chapter

• Understanding how filters work

• Introducing Smart Filters

• Sharpening soft areas

• Improving an image with blurring

• Smoothing defects with Median and Facet filters

• Applying filters repeatedly or selectively

• Fading a filter's effects

Filters have a long and glorious history, ranging from performing essential tasks (such as removing abrasive particles from the oil in your car's crankcase) to even more important chores involving the pixels in your Photoshop images. In both cases, filters (also called plug-ins because they can be installed or removed from Photoshop independently) seize tiny, almost invisible bits of stuff and rearrange them in useful ways. The results are something you'd never want to do without.

This chapter introduces you to the basics of Photoshop's filter facilities and starts you on the road to plug-in proficiency.

You Say You Want a Convolution?

All filters do one simple thing in a seemingly complicated way: They make Photoshop do your bidding. Deep within a filter's innards is a set of instructions that tells Photoshop what to do with a particular pixel in an image or selection. Photoshop applies these instructions to each and every pixel in the relevant area by using a process the techies call convolution (creating a form or shape that's folded or curved in tortuous windings), but which we normal folk simply refer ...