Absolute Beginner's Guide to Digital Photography

Printing press work usually requires that true black and true white have some tone

(or color) to them. This is because of the need for some type of ink to appear on the

paper, or to avoid random coloration if a pure black were to be present. The sliders

on the Output Levels gradient are pulled in a little to a value of usually 97% black

and 3% white.

Correcting Images with Curves

Curves enables you to control the tonal variation in an image. The graph that

appears when you access curves performs a function similar to Levels, but uses a

visual cue—a line on a graph—as the interface between the image’s tones and the

user. In Photoshop you can access the Curves dialog box by choosing Images,

Adjust, Curves.

Curves for People in a Hurry

When you move the line and change its shape (by

clicking and dragging), the image’s tones change

interactively. If you are in a hurry, one quick solu-

tion is to use the classic “S” curve, which boosts

contrast by increasing brightness levels and mak-

ing dark tones blacker. Just follow these steps:

1. Open an image and save it with a new
   name so that you do not alter the original.


2. Choose Image, Adjustments, Curves. In the
   Curves dialog box, make sure the Preview
   box is checked. Time to create the classic
   S curve.


3. In the Curves dialog box, move the diagonal
   line in two places: Click and drag near the top right of the curve and move
   the curve to the left. Afterward, click and drag near the bottom left of the
   curve and drag to the right. The goal is to create the S curve (see Figure
   15.10).


4. Click OK and review the image. If you make a mistake, press and hold down
   Alt. The Cancel button will change to a Reset button. Click Reset and then
   start again, if necessary.

226 ABSOLUTE BEGINNER’S GUIDE TODIGITAL PHOTOGRAPHY

Photoshop Elements

includes a Levels dialog

box but no Curves feature. iPhoto

includes only brightness and con-

trast adjustments.