Adobe Photoshop CS comes with an amazing assortment of tools to help you edit your images. The latest version includes a wide range of features to make things easier, but how can you get the most out of it? In this second part of Chapter 5 from Mordy Golding's Adobe Creative Suite,(Sams, 2003, ISBN: 0672325918), you'll learn various ways to adjust your images, whether you're just trying to clean it up or want to try out some interesting effects.
Using Adobe Photoshop CS, Part 2 - Noise (Page 9 of 12 )
In physics, the word noise is defined as "a disturbance, especially a random and persistent disturbance, that obscures or reduces the clarity of a signal." But as with most things in life, you can take something that appears to be negative and turn it around, making it into a positive-something you can use. At times you may have distortion in certain parts of an image, and adding some noise to that area might improve the overall appearance. Here are two examples:
Most digital cameras save pictures in JPEG format, and the pictures can sometimes contain artifacts (random pixels and anomalies, and so forth). Many times these artifacts appear due to distortion in the Blue channel. Applying some noise to just the Blue channel might result in a smoother and cleaner image overall.
Gradients that span large areas (entire pages, spreads, or large documents, such as movie posters) can print with banding-visible shifts or "steps" of color. This is especially evident with light colors, such as yellow. Adding a bit of noise can visually break up these steps and produce a smoother- looking gradient (although more grainy in appearance).
Tip -Adding noise is also a great way to create background textures and special effects.
To add noise to a selection (or, if nothing is selected, an entire image), choose Filter, Noise, Add Noise. Use the Amount slider to control how much noise is added, and choose Uniform or Gaussian distribution (see Figure 5.128). I find that when you're adding smaller doses of noise, Gaussian looks best, but Uniform gives a better appearance when you're adding large amounts of noise. The Monochromatic option adds only black noise (very useful for mezzotint-like effects).
Figure 5.128Applying noise to a selection.
We've all made the following statement at some point in our lives: "For the price I paid for this computer, it should be making my coffee too." Well, that may be asking too much, but it isn't too much to ask your computer to do repetitive tasks for you while you're busy refilling your mug with your favorite brew.
You'll be happy to know that Photoshop (along with its sibling apps Illustrator and InDesign) has best-in-class support for scripting and automation. You'll also find plenty of premade scripts and features ready to go right out of the box.
So you're probably thinking, "Sure, automation is great and everything, but I don't know-or even want to know-how to write in scripting language," right? Have no fear because Photoshop has something called Actions-which require no knowledge of programming languages or any math, for that matter (I'm not a big fan of math).
The way it works is quite simple. You basically perform a set of operations once to show Photoshop what you want to do, and you save that sequence of events as an Action. Then whenever you want to perform that sequence of events again, you play the script and Photoshop performs all the steps for you.
For example, say you have a CD that you use often, which is filled with RGB stock photos. You can't use the photos as-is, so each time you want to use one of these stock photos, you open the file, convert it to CMYK, change the resolution, and then save it as a TIFF. So you open the Actions palette and click the Create New Action button (see Figure 5.129). You name the file and click the Record button. Then you open a file, convert it to CMYK, change the resolution, and then save the file as a TIFF, all as you would normally do. When you are finished, you click on the Stop Recording button in the Actions palette. And you're done.
Figure 5.129Creating a new Action with the Actions palette.
The next time you need to use a photo from that CD, you can use the Action you recorded to do the conversion for you automatically. Now this may sound nice and all, saving you a few keystrokes, but it gets even better. You can apply an Action to an entire group of files at once, called batch processing. In this way, you can apply conversions to all the images on your CD automatically-all while you go and grab some lunch.
To apply a batch Action, choose File, Automate, Batch and then specify the Action and choose a source location (where the files are being opened from) and a destination location (where you want the adjusted files to be saved). This being Adobe Photoshop, of course, you also have many options on how to name new files, and how to deal with dialog boxes and warnings (see Figure 5.130).
Figure 5.130The Batch dialog.
Photoshop has built-in support for both AppleScript (used on Macintosh computers) and Visual Basic Script (used on Windows computers). If you are familiar with either of these scripting languages, you can tell Photoshop to do just about anything.
Note -Scripts and Actions differ in that Actions are simply a recording of specific keystrokes. Scripts can contain logic and perform functions based on different conditions. For example, in the Actions example mentioned earlier, a script could check what color mode the document is in and perform different functions depending on what the setting is. Scripts can also allow Photoshop to "talk" with other applications. For example, you could have a script do the file conversions and then launch InDesign and place the photos into InDesign and print a catalog of images. Actions are limited to functions within the application.
If you're like me, and can write a script as well as you can write a thesis on the advances of brain surgery in the twenty-first century, then you're thinking that this scripting stuff won't be of much help in your everyday life.
Don't despair, because nowhere is it stated that to use a script, you have to write it yourself. There are plenty of people who write them and post them to the Web, sell them, or even make themselves available to write custom scripts for people. More important, Adobe includes several scripts with Photoshop that you can use right out of the box. You can find these by choosing File, Scripts.
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.