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COLOR BALANCING DIGITAL IMAGES WITH A
These helpful hints are
posted here with the intention of offering
information about one easy way to use a
grey card (Kodak gray card or any other brand)
to get better color results from your digital
I'll start with a question:
If you were in Los Angeles and you wanted to
drive to New York how many different routes
could you take and still wind up in New York?
Lots of routes, right? Ok, well there are countless ways
to get pleasing color and color balance
digital images. This page describes
one method using Photoshop that is pretty
straight forward and works well.
The bottom line in color balance is this:
You need some reference in your image that is
a known neutral color. The gray card is
an easy way to do that.
This will be very basic stuff to some
visitors to this site but it does not hurt to
start from the beginning. I am going to
use some terminology here that is mine, not
scientific, with the intention of putting it
all into terms I can understand. If I
can understand it, anybody can!
"Real Color", as we humans see
it, is the light that is reflected from an
object. There is a source of light: such
as the sun, the moon, artificial lighting, a
camera flash, etc. This light strikes an
object and it is reflected back to our eyes,
which record it and pass it on to the brain,
which interprets it for us.
An apple looks red, or green, or yellow,
because the chemicals in the skin of the apple
reflect back these wavelengths.
But the "real color" of an object
changes as the subtle color tone of the light that shines upon it
For example: We see a piece of
in an office that is illuminated with
florescent lighting. The paper looks
white to us. We take the paper outside
into the bright sun, it still looks white.
We take the paper home with us and look at it
under the tungsten lights that illuminate our
house; it's white. We take it into
the shade and it still looks white to us.
But it's not really pure
white in each of these situations. Our
brain knows that this paper should be white so
it does some fancy interpolating for us.
In reality, the paper in the office probably
had a bluish hue to it, as it did in the shade
too, and it had a reddish hue in our
home, and was maybe slightly yellow in the
Cameras do not have the
wonderful flexibility of the human brain.
Although there is some great technology out
there to make these machines produce the color
that we SHOULD be seeing, by correcting the
WHITE BALANCE of an image as the image is
captured or processed, most of them are 100%
perfect all of the time. There will be
times when an image has a COLOR CAST to it,
maybe a slight magenta, a bit too red, or
There are certain colors
that are very important to humans, we have
been looking at them for thousands of years,
and we can tell when they are "not right."
Skin color is one example. When it's
wrong we know it; we have been looking at
other people our entire life and we know when
it's wrong! Green grass and trees are
another thing that seem to be imbedded in our
brains. When green trees are yellow or
red we just instinctively know something is
The goal of color balancing
is to make the colors "right." We want
white to actually look white and for grey to
look grey. There are exceptions to this,
such as those times when we want the golden
light of a setting sun to look golden, but
let's put that aside for now. For the
most part, if we can get an image to display
white as white, and grey as grey, then in all
likelihood the skin tones of the people in the
photo will be corrected and look normal and
pleasing to us as well.
COLOR AND THE COMPUTER WORLD
When computers render color,
so that we can see color on a monitor or print
it out on paper, they need to do so in a
mathematical format. There are all sorts
of complexities that enter into the display or printing
of color but
the standard that home computers rely upon
most is going to be RGB color. With this
system there are three primary colors, RED GREEN BLUE. Colors displayed on a
monitor or (in the case of most ink jet
printers) are a composite of these three, with
each color have a value of RED, GREEN,
BLUE between 1 and 255. Pure Black is
0-0-0. Pure white would be 255-255-255.
Every other color, all 16,581,375 of them, are
a composite of the three primary colors.
Here are some examples
there is an equal mixture of RED,
GREEN, and BLUE we get GREY ( also
called NEUTRAL) TONES
are a few examples
G 129 B129
DIGITAL PHOTO COLOR CORRECTION
When we take a digital image, the camera
makes it's best guess regarding the
"Color Temperature" of the light
source and the camera firmware adjusts the
color accordingly. Sometimes the result
can be very good, other times it is way
off. It depends on the camera, the way
you have it set, the degree to which the light
is made up of mixed light sources, and a lot
of other things. Fortunately we have
wonderful software that can fix these problems
for us and give us a great range of creative
options as well.
Getting the proper color
balance of an image is probably the most basic
step in image editing. But there can be tremendous confusion among
digital camera users about how to get a good
result. Some software, such as Adobe
Photoshop, appears absolutely alien to
beginners. It takes a long time,
some dedicated study, and lots of experience
to really master Photoshop. But the most
essential tasks, color balancing and tone
control, are really pretty easy in Photoshop
and most other image editing programs.
ENTER THE GREY CARD
One way to "make a photo look
right", is to put something in it that
has a known value. The software can then
correct the color of this one item,
"pulling" everything else in the
photo along with it, and making a very nice
overall improvement. Let's say we have a
photo that has a "Reddish Cast" to
it, in other words the entire photo looks just
a bit too red. I once had a camera that
had a terrible problem with reddish castes, so
I happen to know about this one!