Myth: Once you’ve set up a color-managed workflow, you’ll never again have to color correct images.
Nothing is further from the truth. Color management
and color correction are different animals.
The ultimate goal of color management is to maintain
the appearance of colors in the original artwork
throughout a project’s workflow. Color management
doesn’t correct shortcomings that exist in the original
art. If you start with an image that has weak contrast,
off colors, or poor skin tones, a color-managed workfl
ow will do no more than faithfully render the same
defects in the final output.
But by applying effective color correction at the
right stage in your workflow, you not only protect
the best color attributes present in your original art,
you can address any inherent weak points.
Does every image need color correction?
Most images can benefit from a little editing. At
a minimum, you’ll need to set the end points (the
appearance of highlights and shadows) and gray
balance. An unedited image can look flat and the
colors will probably be off. These initial corrections
will improve overall contrast and show better color
definition. Beyond this, you may choose to fine-tune
contrast across the tonal scale, edit colors selectively,
and perform any other edits required.
Tools that lend a helping hand
Before we look at what I consider the “essential few”
tools for editing contrast and color, you should get
familiar with the full range of tools and features in
Photoshop devoted to color correction.
Histogram: Choose Window > Show Histogram to
access the histogram for the image, layer, or channel
you’re working on (figure 1). A histogram is a map
that shows how tones in the image are distributed
in the tonal scale (imagine a black-to-white gradient
below the histogram data that represents the entire
tonal scale). The histogram data is like a bar chart
that shows the number of pixels in the image that
correspond to tones in the scale. Higher maps mean
there are more pixels in that tonal range, while gaps
in the histogram represent missing tones. Use the
histogram to quickly assess if the image has ade-
quate tonal content for further editing, and to help
you make editing decisions.
Info Palette: Choose Window > Info to view the
densitometer built into Photoshop (figure 2). Use it
to measure the tone and color values in your image.
As you move your cursor over the image, the palette
continuously displays the values of the pixels below
your cursor. You can view readings in the same color
mode as the image (RGB, CMYK, etc.) and get useful
feedback such as the total ink density and opacity.
Choose the display option by clicking the small
Eyedropper in the palette.
Color Samplers: This feature works in conjunction
with the Info palette. The Color Sampler tool,
nested with the Eyedropper tool, lets you keep track
of tones and colors in a specific area of the image
(figure 3). Click on any part of the image with this
tool to place a fixed sampler target on the image.
You can place up to four sample points in an image,
and each registers values in the Info palette in the
display option of your choice. During editing, the
samplers display before and after values in the palette,
making them a good choice for tracking critical
highlight and shadow detail. Samplers are saved
with the file so you can always reference them.
Top pro correction tools
The following professional-strength tools are standbys
for improving tones and colors in your images.
(Note that some of them perform the same or
similar functions.) I encourage you to learn about
them all and experiment with them in your projects.
Ultimately, your results and comfort level with
using each tool will determine which ones you rely
on in your workflow.
Levels: Choose Image > Adjustments > Levels to
access this tool (figure 4). Easy to learn and intuitive,
it’s useful for editing tones and colors and for
setting end points and gray balance. Levels includes
a handy histogram of the selected area, channel, or
image layer. You can edit contrast and colors in the
composite image as well as in the individual color
channels. Two sets of sliders let you adjust shadows,
mid-tones, and highlights. For most of your editing
you’ll work with the Input Levels slider (the top
one), which increases contrast. Levels has a unique
feature: You can view the image in a “threshold
view,” allowing you to visually pick the highlight
and shadow endpoints.
Curves: Choose Image > Adjustments > Curves.
While Levels gives you generous control over the
three main tonal regions (shadows, mid-tones, and
highlights), Curves (figure 5) allows precise control
over the tones and colors in the image. You can
modify the composite or the individual channels
and set end points with the Eyedropper tools provided.
The grid size may be changed by Option-
(Mac) or Alt- (PC) clicking on the grid itself. Use
the small double arrows in the gradient to toggle the
grid display from 0–255 levels and 0–100 percent
density. The diagonal line controls input and output
values. As you manipulate the curve in the direction
of the light shades (shown in the corresponding
vertical gradient), tones are brightened; conversely,
as the curve bends in the direction of the darker
shades, pixels are darkened.
Hue/Saturation: Choose Image > Adjustments >
Hue/Saturation to edit colors (figure 6). This tool
lets you creatively colorize the image by converting
it to a single hue; broadly shift the existing colors
with hue, saturation, and lightness as the criteria;
and perform selective color correction by limiting
color editing to a specific range of hues. Use this
tool to saturate or de-saturate colored areas, remove
color casts and contaminants in a specific color
range, and to create color effects.
Color Balance: Choose Image > Adjustments >
Color Balance to finesse this aspect of your image
(figure 7). With its simple interface, this tool allows
you to make subtle color changes within the three
main tonal regions. It’s based on the principle of
working with complementary or opposing colors
on the color wheel. To add a cyan cast to a colored
area, for example, you move the slider toward it and
simultaneously away from its opposing color, red.
Selective Color: Choose Image > Adjustments
> Selective Color to isolate and edit a specified
color (red, green, magenta, etc.). This tool (figure
8) works best when applied to a selection, or via
a masked adjustment layer. Activate the Absolute
option at the bottom to create predictable results.
Another nice feature is the ability to visually adjust
a color cast in the highlights, neutrals, and shadows
of the image.
Correction checklist
• Use Adjustment Layers whenever possible. One of
the most valuable techniques in color correction is
the use of Layers and Adjustment Layers. (Almost
all of the tools referenced here can be applied via
an Adjustment Layer.) You create one by clicking
the Create New Adjustment Layer icon at the bottom
of the Layers palette, and choosing the desired
tool. The results are identical to applying the effect
directly to the image, and you have the benefit of
keeping changes ordered and flexible throughout.
You can also build multiple adjustments to address
different color problems, and Adjustment Layers
may be used in conjunction with selections and
masks to limit changes to certain areas of the image.
• Calibrate and profile your monitor regularly. It’s
no exaggeration to say that this is the single most
critical step in color correction.
It’s workflow time!
Now let’s put some of this knowledge to work. The
following 8-step workflow is offered as a model that
you can adapt to whatever project you have at hand,
adding tools as necessary. To keep it simple, I’ve not
attempted to include every potential correction.
A Model for a Color Correction Workflow
Step 1: Convert the colors in the image to a working
space profile. Choose Edit > Convert to Profile.
Choose a working space that matches the gamut and
dynamic range of the final output (Adobe RGB or
ColorMatch RGB for photographic or print work,
sRGB for web). This gives you a palette of deviceindependent
colors for editing your image.
Step 2: Use a Levels adjustment layer to set up good
end points for printing. If you see empty space on
either end of the histogram, it means that there isn’t
adequate detail in these regions. Bring
the black and white Input Levels sliders to where the
data starts in the histogram. This stretches the tones
to fill the tonal scale, and results in brighter highlights
and deeper shadows.
Step 3: Fine-tune contrast using a Curves adjustment
layer. Set up and manipulate a “lockdown
curve.” This is a default (diagonal) curve with points
placed at 10 percent increments on the grid. Save a
lockdown curve for both grid formats for use on a
variety of other images. Tip: If you find
that the edited contrast has intensified or altered
colors in the image, change the blending mode of
the Curves adjustment layer to Luminosity. This
adjusts contrast, but not colors.
Step 4: Use Hue/Saturation to adjust a specific
color range in the image. Create multiple
named Hue/Saturation adjustments.
Step 5: To keep things flexible, apply Sharpening
on a separate layer that combines all of the following
adjustments. Create a combined layer by targeting
the top-most layer in the stack, and type Command
+ Option + Shift + E (Mac) or Control + Alt + Shift
+ E (PC). Use the Unsharp Mask or Smart Sharpen
filter. To sharpen some areas of the image, “paint in”
sharpening with the use of a layer mask. Tip: Apply
the High Pass filter (Filter > Other > High Pass) to
a duplicate or combined layer set to the soft light
blending mode . This technique produces
high-quality sharpening and restricts sharpening to
edges and color transitions in the image.
Step 6: Save a master RGB image in PSD or TIFF
format with Layers intact. Embed color profile.
Step 7: Soft proof final output. Make any additional
edits as separate adjustment layers.
Step 8: Convert a duplicate image to final output
space after flattening Layers.
SIDEBAR: Robo-correction?
Color technician and
workflow specialist
David E. Troutt explains
why you can’t
rely on a profi le to
correct gray balance
or set end points
correctly upon color
conversion: “A typical
printer profi le is calculated
by measuring
700 to 1,500 patches
of color. A 24-bit
RGB color image can
contain millions of
colors, which makes it
impossible to describe
its color gamut accurately
to a color management
system. This
is why we use color
correction tools—to
bridge this gap and
set up colors the way
they need to appear in
final output.”
Another factor is how
we perceive colors.
When building profi les
or proofi ng—for the
vast majority of images—
a numeric color
match governed by
the printer profi le will
produce good results.
But when images contain
delicate detail in
highlights or shadows
that are critical, or
when a specific color
range needs extra
care in handling—such
as skin tones, memory
colors (sky, grass,
etc.), or product colors—
manual color correction
techniques will
bridge the differences.
PRO TIP: Use Luminosity To Avoid Color Shifts
At times, making a steep change to image contrast or
applying heavy sharpening to a saturated image can
alter the appearance of colors in the image, making
them appear more vivid. You can avoid this by restricting
the contrast adjustments and sharpening to just the
brightness levels in the image.
Here’s how: Change the blending mode of the contrast
adjustment layer (or the duplicate layer created for
sharpening) to Luminosity. If the adjustment or sharpening
was applied directly to the image data, then choose
Fade from the Edit menu (for Mac, type Command +
Shift + F; on PC, type Control + Shift + F). Then change
the blend mode from Normal to Luminosity. This simple
move restricts the edits and protects the colors.
