eBook, !! e-BOOK !!, fotografia, Digital Photography - Acquisition And Processing Techniques By Ron Reznick
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Table of Contents
Introduction
.......................................... 3
Acquisition
Processing
Exposure and the Histogram
Deinition of Terms........................... 4
The Histogram Deined .................... 6
Evaluating Luminosity ..................... 7
Understanding Color ........................ 10
Working with Color .......................... 11
The Digital Worklow
The Transfer Process......................... 29
IPTC Caption/Transfer Options....... 30
Performing a Transfer....................... 31
Batch Processing................................ 32
The Selection Process........................ 33
Metering
Which one do I choose and Why?..... 13
Matrix .................................................15
Spot .....................................................16
Center................................................. 17
Image Processing
Nikon Capture Program Setup ......... 34
Great Egret ........................................ 37
Black Crowned Night Heron ............ 41
Jean-Claude ........................................ 46
Chilean Jasmine ................................ 50
The Vietnam Memorial .................... 55
Hard Rock Stratocaster ..................... 58
Moose at Sunrise ............................... 61
Tomb of the Unknown Soldier ......... 65
Digital DEE: an overview ................. 68
Jackson Lake, Grand Tetons ............. 71
Composition
“the rule of thirds” ............................ 18
Guiding the eye ................................. 19
Angles, near/far technique ............... 20
Closeup work ..................................... 21
Using the focused plane .................... 22
Breaks in convention & luck ............ 23
Architectural lines ............................ 24
Photoshop Processing
CS RAW — BC Night Heron............. 74
Post-processing .................................. 78
Tips and Tricks
................................... 26
Images for your Enjoyment
............... 28
Lenses
(from Digital-Images.net) ......... 86
Thanks are due to Dave Cheatham, Andrew Chan,
Mike Worley, Kevin Gallagher, Vince Battaglia and
Rick Wallace for their assistance in this project.
2
All text, graphics material and images
©
2004 — Ron Reznick
All Rights Reserved
RR Design
636 E. Harvard Rd unit B
Burbank, California 91501
Telephone: (818) 843-8212
t
exposed, well-composed, properly-
processed images. This book is not intended
to be a camera or software manual which
expounds on features… instead I prefer to
go into detail regarding various techniques
which I use for the acquisition and process-
ing of images. While I use Nikon gear, the
techniques which I will describe are appli-
cable to other manufacturers’ products, and
techniques described for processing images in
Nikon Capture are applicable to other RAW
processing programs and image editors with a
few alterations.
Some acquisition techniques which will
be discussed include the use of the histogram
to determine proper exposure; the use of the
various metering modes along with exposure
compensation to achieve that exposure in
various situations; some reasons for the use of
aperture priority, shutter priority or manual
mode; techniques for composition of various
sorts of subjects; and the use of depth of ield
for subject isolation or to assist in the creation
of a wide-angle composition.
Special attention will be paid to the digital
worklow, including organizational methods;
batch-processing for pre-selection (to remove
unwanted duplicates or mistakes from the
group to be processed manually); the selection
process itself; and a comprehensive treatise on
image processing using Nikon Capture as well
as some post-processing techniques in Pho-
toshop. In my worklow, most of the image
processing including the color work, White
Balance, EV, Levels, Curves and Gamma
processing are done in Capture, with post-
processing being primarily used for touch-up,
rotation, cropping, resizing, etc. The section
on processing is documented with screen cap-
tures and presented in easily-understandable
language.
Zoom in to examine image details
.
An article on Lens Selection and sample
images are also included, along with lessons
showing step-by-step processing of these im-
ages, which were selected to illustrate com-
mon histograms. There will also be auxiliary
iles included to help you to understand lumi-
nosity and color, and how they apply to both
metering and evaluation of the histogram.
3
T
he best photographs result from well-
Exposure and the Histogram: A Deinition of Terms
probably aware of the terms and
features I’m going to discuss. If you already
know this stuff, bear with me or skip forward
a bit.
One of the most powerful things about
digital cameras is the ability to see what we’re
doing… not only can we see the image itself,
but we can turn on a
Histogram
: a graphic
distribution chart that shows the image in
terms of light levels and the number of pixels
that are present at each level. The histogram is
a chart running left to right from 0 (Black) to
255 (White) with divisions at 64, 128 (middle
grey), and 192 (see image to right).
The histogram allows us to see the ex-
posure. If you can evaluate the light levels
(
luminosity
) of the scene, you can look at
the histogram and determine whether you are
underexposed or overexposed — for instance,
I was with a student in Yellowstone National
Park recently, and we were shooting some
pronghorns in strong light. I pointed out to
him that the white part of the pronghorn was
240, and to expose accordingly. He took a shot,
checked his histogram, and saw the highlights
dropping off just past the 192 division on the
histogram. He applied +0.7 EV (
E
xposure
V
alue
Compensation)
and took another shot,
nailing the exposure right on the money.
The numbers below the vertical divisions
correspond to luminosity level at each division
in RGB value (RGB is Red, Green, Blue)
.
There
are also greyscale (K) equivalents to each of
these values, from left to right on the histogram
they are 100%K (Black), 75%K (64RGB),
50%K (128RGB), 25%K (192RGB) and
0%K (White). The greyscale values correspond
to the percentages seen in the greyscale below.
What does the EV control do? The EV
control alters the exposure by raising or low-
ering the aperture or shutter speed. If you
have your camera set to
Aperture Priority
,
the aperture (lens opening) is ixed. When
in
Shutter Priority
the shutter speed is ixed.
The EV control alters the one that isn’t ixed,
opening up the aperture on the lens or lower-
ing the shutter speed for positive EV, and clos-
ing down the aperture or raising the shutter
speed for negative EV.
If you overexpose an image, the contrast is
lowered and it is possible to severely overexpose
highlights. This will result in a large spike on the
right side of the histogram (255) and a loss of
highlight detail.
If you underexpose an image, the shadows
and midtones start to get too dark (block up),
and to recover this underexposure yields a noisy
result.
4
M
any people reading this book are
Another powerful feature of the digital
camera is the ability to alter the
ISO
(ilm
speed) without changing ilm (since we don’t
use ilm). This works the same as the volume
control on your stereo -- it cranks up the gain.
As the signal-to-noise level is ixed (the noise
is increased along with the signal level when
you “raise the volume”), raising the ISO speed
increases the shutter speed for a given aper-
ture and exposure at the cost of a higher level
of noise.
On the following pages, I am going to get
into some rather exhaustive detail regarding
the histogram, and will show you how to use
a greyscale and color charts to train your eye
to see
luminosity
(light levels) in the subjects
around you. This will give you a reference to
light levels that will assist you when looking
at your histogram, so you can judge when an
image is overexposed or underexposed.
I am providing you with several iles that
will allow you to calibrate your eyes (and
incidentally adjust the brightness and con-
trast of your monitor in case you aren’t using
calibration tools), teach you about color and
greyscale luminosities, and RGB color levels.
If you spend some time studying these as out-
lined in the pages to come, you will soon turn
into a human light meter and will be able to
closely estimate the level of highlights and
midtones, and therefore will be able to look
at the histogram and
you will know
whether
or not you have the exposure correct. The
freedom this gives you is tremendous. I wish
you could see the looks on the faces of my stu-
dents when they realize they are consistently
hitting exposures within one-third stop, and
often within one-tenth. BIG smiles.
If you set your aperture to get the depth of
ield you want, and the exposure is correct but the
shutter speed is too low, raising
ISO
increases the
shutter speed at the expense of additional noise.
You’ll have a sharper shot, but with more noise.
shadows
midtones
highlights
The left side of the histogram shows the
shadows, the right side shows the highlights.
Midtones are in the middle. You want to acquire
the ability to estimate luminosity values of the
midtones or highlights so you can adjust the EV.
The histogram above shows the RGB values
associated with each division of the histogram as
well as a greyscale, and a very important piece of
information: the distance in EV between each of
the divisions from the mid-shadows to white. If
you practice, you will learn to evaluate the sub-
ject and highlight luminosities, and can look for
them on the histogram. With known values, you
can make adjustments based on a knowledge of
the distance between the divisions and adjust the
exposure as close as your camera will allow.
Plan on reading the following informa-
tion several times to understand it. This is not
rocket science, of course, but the information
requires some digestion before it becomes
second nature. Open the greyscale and color
charts in your image editor several times per
week. Put your mouse cursor over the color
patches and get to know the RGB levels (look
in your Info palette). Soon, you’ll have a good
feel for luminosity.
5
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