Adobe® Photoshop® CS2 Studio Techniques

Avoiding Posterization

If you notice the histogram developing gaps that sort of look like a comb (Figure 6.82), then you'll want to keep an eye on the brightness levels that are directly below that area of the histogram. Gaps in a histogram indicate that certain brightness levels are nowhere to be found in your image, which can indicate posterization (stair-stepped transitions where there would usually be a smooth transition—as in Figure 6.83). That usually happens when you make part of a curve rather steep. As long as the gaps are small (two to three pixels wide), then it's not likely that you'll notice it in your image. If they start getting a lot wider than that, you might want to inspect your image and think about making your curve less ...