Adobe® Photoshop® CS2 Studio Techniques

Recognizing Posterization

When you look at an updated histogram, you might see wide gaps in the histogram—this indicates posterization (Figure 5.35). Posterization is when you should have a smooth transition between areas and instead you see a drastic jump between a bright and dark area. Some call this banding or stair-stepping. As long as the gaps in the histogram are smaller than three pixels wide, you probably won't notice it at all in the image.

Figure 5.35. Gaps in a histogram indicate posterization.

Adjusting the image usually causes these gaps. As you adjust the image, the bars on the histogram spread out and gaps start to appear (remember ...