In this tutorial we'll begin looking
at color adjustments.
I must state here that there's a big difference between adjusting
color for accuracy and enhancing it artificially to be something
it's not. Any color correction will be suspected if the results
fail to represent the color correctly or accurately.
That being
said, I think it's good to know how easily color can be manipulated
so that there is some healthy scepticism for some images that look
too good to be true.
So, let's look at the simplest color correction method,
which is an overall tonal correction of the whole image. We'll
start with two images of the same cultivar. The top image is more
accurate. At least to my eye, this truly shows the color I see
in the garden. I understand this is subjective, but the color of
the second image appears too yellow and washed out - partly this
is the exposure and partly it's the color of the light at that
time of day - you'll notice the foliage too has a yellow cast to
the leaves.
Now, before we can begin we need to spend a moment talking about
color theory on a computer monitor versus the color theory we were
probably taught in art class. In art classes (and I have a BFA
Degree in Painting, so I have suffered through a few) they taught
us that the primary colors are Red, Yellow and Blue. Mix red and
yellow to get orange, mix yellow and blue to get green, and mix
red and blue to get violet; the secondary colors. These, red, yellow
and blue, are are the primary colors for pigments. When we see
a red rubber ball, we see the color red because the pigments in
the covering on the ball absorb all the other colors and only reflect
back to our eyes the color red. This is sometimes called the subtractive
color wheel.
Computer monitors, however, use a completely different set of
primary colors, as does your TV set. The primary colors of light
are Red, Green and Blue; (thus RGB Monitors) the secondary colors
are yellow, cyan and magenta. Look closely at your color TV and
you'll see red, green and blue dots or stripes make up the image
(this works only on CRT TV sets, not LCD sets). TVs and computer
monitors create colors by mixing light. This is called the additive
color wheel.
So, in this case, we are not mixing pigments, we are mixing light.
In theory, if were were to mix red, yellow and blue pigments together
we should get black (it never works that way, it's a dark, muddy
brown). If we mix equal parts of red, green and blue light - we
get white. Using the RGB Model, to make magenta, we mix red and
blue light, to make make cyan we mix blue and green light and the
one that throws lots of people, to make yellow, we mix red and
green light!
Now, why is this important? We are going to try to correct the
color in the lower image. To 'fix' it, we need to shift the overall
color balance away from yellow - but what color do we add? You
pick the color on the opposite side of the color wheel - so, since
yellow is made up of red and green, the compliment is blue! So,
to adjust this photo, we'll be adding blue light to the image.
(Here I should mention too; I never adjust an original photo.
I open the file, do a Save As... and give it a new name and open
that file to adjust. I then have a record of what the photo originally
looked like.)
Photoshop and Photoshop Elements both have the tool we'll be using
in this tutorial. Open the picture you wish to adjust and then
go to the Image Menu - pick Adjustments - and then pick Variations.
This dialog will appear:
Looking at this dialog you see that there are 3 images labeled
"Current Pick". At the top you see it compared to the original image.
On the right side, you see it between a lighter and darker version.
And, last, in the center of the RGB color wheel.
By default, the
dialog opens with the midtones selected (see the upper right area)
and midway between Fine and Course corrections. I like to set this
slider more toward the Fine side than Photoshop sets by default,
but I left it there so you can see the obvious shifts of color
and brightness. As you move the slider toward Fine these changes
will become more subtle.
To make an adjustment click once on the correction you desire.
The "Current Pick" will now have that adjustment applied.
Click additional times for additional corrections,
A couple
of pointers when using this dialog. First, if you Cancel, nothing
changes. If you get adjustment happy and feel you've gone way too
far, clicking Original at the upper left brings the "Current Pick"
back to the original so you can start again. In adjusting color,
if you are working on the color wheel and add blue three times
and feel twice was better - you can click once across the color
wheel, in this case on yellow, and it will "back up" one correction.
In my image, I moved the adjustment slider to almost Fine and
clicked twice on blue and once on Darker and then saved the image.
To illustrate the change, the right side of the image below is
the adjusted side and left is the original color and exposure.
Now, if you look at the color above you can see it's perhaps not
perfect, but it is closer than the unadjusted image to the top
photo on this page. Notice too how the foliage has been adjusted
as well and that there are some noticeable blue tones now. The
top image's foliage also has some small blue toned areas. Note
that this adjustment isn't too dramatic - if you can tell by looking
that an image has been adjusted, then you probably have over corrected.
One other part of the Variations Dialog should be explained here
as well. Just beneath the Fine-Course slider is a checkbox labeled
Clipping. Clipping is the shifting of pixel values to either the
highest highlight value or the lowest shadow value. Clipped areas
are either completely white or completely black and have no image
detail. If you were to shift to adjusting shadows you might see
this:
Photoshop uses bright versions of the complimentary color (the
one on the opposite side of the color wheel) to indicate that making
this adjustment will drop these areas of the image off the range
the monitor can show - you have reached zero value for that color
in the area so indicated. While this isn't even always bad, if
I don't say something folks might think that this adjustment is
going to insert those wild bright colors - NO! If you uncheck the
Clipping checkbox you can still see the results you will get, and
as I said, they aren't always bad, but Photoshop does warn you
when you clip colors.
Next tutorials we'll look at a number of other tools for adjusting
color - some that act like a photographer's grab bag of tools and
some that are, indeed, close to magic.
Tim Fehr - Eau Claire, WI
© 2007 by Tim Fehr - all rights
reserved.
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