6 Automatic corrections
Although
these weren't in the case study, as the simplest form of correction,
they should come first. They should also be the first thing to try if
a picture looks the wrong colour.
Auto
Levels
Applying
the Auto Levels adjustment to this very blue photo...
It
goes horribly wrong! The sea is inky dark and everything has gone
purple.
It's
a common problem: If the software in your camera gets the colour
wrong, its not surprising another piece of software also gets it
wrong. Sometimes it goes so spectacularly wrong the results are
actually quite interesting in their own right.
The
problem is that this photo is meant to be mainly blue. No software
can 'see' the picture. All these programs ever do is analyse the
distribution of light, hue, etcetera and calculate adjustments
accordingly. But all is not lost.
Fade
Auto Levels
In
the edit menu, Photoshop helpfully provides an option to fade the
last effect applied. Click on that tool and you get a slider from 0%
to 100% and the picture changes as you move the slider so you can see
exactly what you're doing.
Fading
the Auto Levels to 50% makes a positive difference.
However,
the same result could just as easily be got by tweaking the contrast
and brightness. I'll do that in a bit to show you there is more than
one way to skin a cat. (N.B. No cats were hurt during the writing of
this book).
Personally,
I don't trust Auto Levels. I can't remember the last time I let it
have it's own way. Typically, I fade it to between 20% and 60%.
Really though, it's just about playing with the slider and seeing if
you can get the result you want. If not, then undo it and try another
tool.
Auto
Colour
My
advice on this tool is just don't! You'll be tempted because it's
right there, next to Auto Levels, but I have very little use for it
and you're going to see much better ways of controlling the colour,
very shortly.
If
you really must try it for yourself, be prepared for disappointment.
Applying
Auto Colour to the original photo, turns the blue sky grey, the sea a
muddy green and the whites quite clearly aren't. There is still an
option to fade this effect but it's clearly doing entirely the wrong
thing.
There
are plenty of times when Auto Colour works just fine, but what it
does then isn't really that helpful. It generally reduces the
vividness of my pictures. My camera is set on Vivid (roughly the
equivalent of Chrome film in ye olde film camera) so I don't want my
photos converted back to Normal.
I
know I sound negative about these two tools but I don't mean to be.
In fact, I urge you to try them before you try anything else. You
never know your luck. Just be prepared to undo the changes and try
something else, such as the Brightness/Contrast tool.
Brightness/Contrast
Although
this isn't an automatic tool, it's so basic I didn't feel it needed
its own chapter.
Select
this tool from the Image-Adjustments menu and you get two sliders:
one for Brightness and one for Contrast.
This
is the result of +25% Contrast and -10% brightness. It's still very
blue but the pure white of the wind turbine and the plumage, show us
that it's actually meant to be blue. What the contrast adjustment has
done (and that's a heck of a lot of contrast to add) is remove the
haziness of the original and sharpened up the details.
Adding
contrast brightens light pixels just as it darkens dark pixels.
That's why I took the brightness back down 10%, to correct for the
increased whiteness of the wind turbine.
White
is always a problem if we're increasing its brightness. Lightening
white so often leads to what's called “blowing out”. It's
demonstrated later, when I show you a better way of altering
brightness.
The
Brightness/Contrast tool still did a decent job of cleaning up this
example though and it's certainly worth a try if you have a hazy
photograph. I personally prefer this result to the one I got with
faded auto levels.
Now
though, I'll take you through the tools I used on that church window:
the tools I use most of the time.