Don't Destroy Those Pixels!

Your pixels never did anything to hurt you, did they? You, on the other hand, are likely roughing them up every time you enhance an image. Directly adjusting color, contrast or focus, all staples of image digital enhancement, physically alters your original data. You may not care all that much about your pixels now, but you will when you realize you’d like a “do over” and they shrug and say “so sorry.” Fortunately, Photoshop has a host of techniques that fall under the category of nondestructive editing (NDE). They allow you to make the changes you want without ever touching your original data.

1. Don’t Slack, Make Sure You Back (Your File)

The simplest start, of course, is to make a backup of your file before the pixel plundering process begins. This is highly recommended, irrespective of whether you follow the remaining suggestions in this article or not. Next, always duplicate your background layer by dragging it onto the New Layer icon at the bottom of the Layers panel before doing anything else. By preserving that background layer, your Photoshop file will always contain the original pixels.

2. Love Layers for Adjustment

Photoshop’s image enhancing commands can be found under Image>Adjustments from the main menu bar. There are adjustments to fix contrast, color, exposure, convert to black and white, etc. This last adjustment, Black & White, is a great example of a problem with these adjustments. When you select the Black & White adjustment, Photoshop, with some settings from you, converts your image, throwing away all of the color information. Not only is the information gone, the conversion settings are also history. There is a better way. Just above your Layers panel, and new to CS4, is the Adjustments panel. If you don’t see it, select Window>Adjustments from the menu bar. Most of the adjustments are available here. But the difference is that these are layers, not commands. When you select one, it shows up as a new layer and its settings become available in the Adjustments panel.

Rather than actually changing pixels, an adjustment layer stores the adjustment instructions, pixel by pixel. The image displayed by Photoshop is as if the adjustment was performed. In fact you can turn off visibility of the layer and the adjustment will disappear. Furthermore, if at some later time you wish to modify the settings for the adjustment, you can select that layer and all of your original settings come back, available for tweaking. The original pixels are untouched and the original settings are always available.

3. Make Masks For Local Changes

When you create an adjustment layer, the result is global, meaning all pixels in your image are affected. What about when you want to localize the effect to a specific object in your image? The old you might have done a selection around that object and then modified it with the Image>Adjustment commands. The new you should consider selecting that object and then creating the adjustment layer. When you do, the layer mask that automatically comes with the adjustment layer (the little thumbnail to the right of the icon) will reflect your selection, restricting the effect of the adjustment to your original selection. Where the layer mask is white, the adjustment shows through; where it is black, the adjustment is blocked. The beauty of this approach is that the mask (your original selection) can be altered later if necessary. You can use a white or black brush to touch up locations where your original selection might have been off.

4. More Masking Mania