- Apply the Auto Tone function. In the Adjust-
ments panel, click the Auto button to apply the
Auto Levels function. The histogram stretches
to fill the center of the dialog box, but the nu-
merical Input Levels values stay the same, as in
Figure 6-25. (You’ll see why in the next step.)
As before, Photoshop’s automated adjustment
isn’t perfect, but it’s a good jumping-off point. - Switch to the Red channel. Choose Red from
the Channel pop-up menu or press the short-
cut, Alt+3 (Option-3). You now see the Red-
channel histogram with adjusted Input Levels
values, as shown in Figure 6-26.
PeaRl Of WISDOm
Clicking Auto in Step 7 changed the Input Levels settings
on a channel-by-channel basis. So even though you see
an altered histogram in the composite view (as in Figure
6-25), you have to visit the individual channels to see the
numerical changes.- Expand the shadows. Notice the black and
white slider triangles directly below the his-
togram (highlighted red in Figure 6-26)? They
correspond to the first and last Input Levels
values, respectively. In my case, the black slider
tells me that any pixel with a brightness of 80 or
less will be made black in the Red channel; the
white slider says any pixel 255 or brighter will
be made white. (This is to be expected given
the overall lightness of this particular image.)
Your values may differ slightly. Remember, 0
is absolute black and 255 is absolute white.
If grabbing and moving those triangles doesn’t suit your
mood or manual dexterity, you can change the value
by selecting the numerical value inside the box on the
right and typing the new value. If you want even greater
control, you can nudge the values with your arrow keys.
Click inside any of those boxes and use the � or � key
to move the sliders in 1-step increments. Holding down
the Shift key with the arrow keys moves the sliders in
10-step increments.Figure 6-25.
Figure 6-26.202 Lesson 6: Adjusting Color and Luminance