Levels, Curves and Hue/Saturation adjustment layers can be used to manage
tone, contrast and color. Which adjustment is better? There is no
direct answer. Each one has their strengths. Let's explore these
A color range is a series of one or more colors that are contiguously located
color wheel. A color channel is the color and tonal information for
one of the colors in a color model. More information on color ranges and
color channels can be found on the
Color Ranges and
Color Channels page.
Hue/Saturation allows us to edit individual or all color
ranges. The Hue/Saturation color ranges are red, green and blue and
their complementary opposites of cyan, magenta, yellow and Master. The
Master color range is all colors. When working with color ranges, we are
working only with those pixels whose dominant color is in the selected range.
Levels and Curves allow us to edit individual or all color channels.
When working with color channels, we are working with any pixel that has
information in that channel.
With a Hue/Saturation adjustment layer, when we pick a specific color range, the
sliders affect only those pixels whose dominant color matches the color range
being edited. In both Levels and Curves adjustment layers, if we edit a
color channel, the adjustment we make will affect every pixel that has any
information in the specified color channel, even if that color is not the
In Figure 1A, there are three color chips. Each color chip has some
red, green and blue in them. But each has a different dominant color.
The single dominant RGB color channel for each chip is as follows: chip 1 is
Green, chip 2 is Red, chip 3 is Blue.
Assume we wish to darken the green color chip. Using a Hue/Saturation
adjustment layer with a blending mode of Normal, I used the eyedropper tool
to click the green chip and then moved the Lightness slider to -100 (negative
100) as in Figure 2. The result is Figure 1B. The green chip has
been darkened and notice that chips 2 and 3 have been unaffected.
Likewise, if we move the Lightness slider to +100, we get the light green as
seen in Figure 1C.
Figure 1A. Three Color Chips
Figure 1B. Dark Green
Figure 1C. Light Green
Figure 2. Dialog Box
Now, lets make the same adjustments using Levels. I created a Levels
adjustment layer with a blending mode of Luminosity. I then changed the
Channel drop down box to Green and moved the middle slider until the gamma Input
Level read 0.29. The result is in Figure 3A. As we can see, the
green chip has been darkened the same amount as in Figure 1B, but chips 2 and 3
have been darkened also. This is because Levels and Curves affects all the
pixels that have green information. And since color chips 2 and 3 have
green in them, they were affected. Color chips 2 and 3 were not affected
by Hue/Saturation because green is not their dominant color. I then moved
the middle slider until the gamma Input Level read 3.65. The result is in
Figure 3B. As we can see, the green chip has been lightened the same
amount as in Figure 1C. However, once again, chips 2 and 3 were modified
Figure 3A. Dark Green
Figure 3B. Light Green
Figure 3C. Levels for Dark Green
Color ranges can be used with Levels and Curves, but it requires a two step
process. Step one creates a selection by color range. Step two creates a
Levels or Curves adjustment layer using the selection as a layer mask. The
details of using color ranges with Levels or Curves is discussed on the
Using Levels and Curves with
Color Ranges page.
Since it requires additional steps to use Levels or Curves to edit by color
range, why not use Hue/Saturation all the time? There are two reasons why
Levels or Curves could be the better choice.
First, we can darken or lighten a color using Levels or Curves more than we can
with Hue/Saturation. In Figure 4A below, the green color chip is the
darkest green we can get with this particular green using the Hue/Saturation
Lightness slider. With Levels and Curves, I can make it even darker, as
seen in Figure 4B. In fact, with Levels or Curves, we can darken it to the
point it is solid black. Likewise, we can lighten a color further with
Levels or Curves. In Figure 4C below, the green color chip is the lightest
green we can get with this particular green using the Hue/Saturation Lightness
slider. With Levels and Curves, I can make it even lighter, as seen in
Figure 4D. We can even lighten it to the point it is solid white.
(For Figures 4B and 4D, a layer mask was used to prevent color chips 2 and 3
from being modified and the blending mode was Luminosity.)
Figure 4A. Hue/Saturation Dark Green
Figure 4B. Curves Dark Green
Figure 4C. Hue/Saturation Light Green
Figure 4D. Curves Light Green
The second reason is the Lightness control on Hue/Saturation is linear.
This means if the color range includes both dark and light colors,
Hue/Saturation will adjust both equally. With Levels or Curves, we have
the additional ability of adjusting either the dark or light versions of the
color, but not the other. This gives us increased control over our
adjustments. Figure 5A is of two color chips. Chip 1 is dark cyan.
Chip 2 is light cyan. In Figure 5B, a Hue/Saturation adjustment layer was
used to lighten the dark cyan. However, it also lightened the light cyan,
which is not what we wanted. In Figure 5C, a Curves adjustment layer was
used to lighten the dark cyan without affecting the light cyan. The Curves
adjustment used to create Figure 5C can be seen in Figure 5D.
Figure 5A. Original
Figure 5B. Hue/Saturation
Figure 5C. Curves
Figure 5D. Curves Dialog Box
With Levels and Curves, we can modify the tonal range to a greater extent
than we can with Hue/Saturation. We can use either Hue/Saturation, Levels
or Curves to adjust by color range. However, using Levels or Curves to
adjust by color range is more involved. We cannot use Hue/Saturation to
adjust by color channel. We can easily use Levels or Curves to adjust by
color channel. Hue/Saturation is a linear control and will affect all
tones equally. Levels and Curves gives us the ability to narrow the tonal
range we wish to change.
When using Levels or Curves to adjust tone, I usually
change blending mode to Luminosity. If left to Normal, we run the risk
of adjusting color as well as tone.