Chapter 1. Adjusting Image Brightness and Contrast

The foundation of a solid digital image begins with the lonal qualities of the file—the brightness and contrast. If these are not adjusted correctly, the rest or the process suffers That's why our workflow begins here. Even if you already feel comfortable adjusting the tones in your images with these tools, you may want 10 look at this chapter. In addition to covering the basics, I show you some cool things that are new in Photoshop CS3.

Understanding Histograms

The primary tool that's used 10 evaluate the tones in a digital image is the histogram. A histogram is a graphical representation of the distribution of the tones in an image. It consists of a graph that ranges from pure black on the left lo pure white on the right. In between are all the shades of gray from almost black to almost white.

Imagine 256 side-by-side columns, one for each of the individual tonal value that a histogram represents. The columns stan with black (0) on the left and end with white (255) on the right. In between are 254 other columns representing all the shades of gray between black and white. Together these 256 levels equal the sum total of the tones in an image.

The height of a column is governed by the number of pixels in the image having that particular tone. If the ...

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