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Chapter
5
The
Digital Darkroom
Although I personally know at least two nature photographers who use
digital cameras but don’t own a
computer, the vast majority of DSLR users will of course want to view
and process their photos on a computer system. For casual
birders, just about any reasonably modern computer system will do,
especially if they’re satisfied with just viewing the photos as-is,
without applying any sort of color correction or other basic image
processing. For the more ambitious photographer—especially those
planning to purchase a system in the near future—a few pointers may
be helpful in selecting both the hardware
(the computer, monitor, card
reader, and back-up drives) and the software
to be incorporated
into your digital darkroom.
The goal of this chapter is to provide
some of those pointers. A detailed treatment of computer-based
image processing techniques is deferred to Part III (“Postprocessing”), while the selection of a
digital printer is addressed in Part IV (“Distribution”).
5.1
Choosing a
Computer
For those in the process of
shopping for a computer, there are a few things about modern computers
that may be useful to know, such as how fast a computer needs to be for
serious image processing, and how much memory and disk space are
needed. Unfortunately, as DSLRs continue to increase in their
megapixel capacity (resulting in increasingly large file sizes for
individual images) and as software continues to increase in
computational complexity (and therefore CPU speed demands), a computer
system which is adequate today may no longer be adequate
tomorrow. As such, we will consider the issues in a very generic
manner, hopefully enabling you to make intelligent buying decisions
even as the technology continues to evolve.
5.1.1
Mac Versus PC
The first question to ask when buying a new computer is which of the
two most popular—and largely incompatible—computer architectures is
right for you. In other words: Mac
or PC (i.e., Apple or Microsoft).
At present, Microsoft Windows
systems are far more
popular for general home use than Apple
Macintosh systems, though Macs
are gaining in popularity. Furthermore, Macs have long enjoyed
a somewhat elevated popularity among digital artists and image
processing professionals. Fortunately, the industry-leading image
processing software package, Adobe
Photoshop, is available for both
systems. Furthermore, either system can, with special software
(e.g., Parallels, or VMWare), be made to run some
programs designed
for the other architecture, though doing so often involves some loss of
speed and may impose other limits (such as access to available memory
or disk space). I personally use only Macs for image processing,
and have found them to be far more reliable than any of the Windows
PC’s I’ve owned in the past—and I’ve owned many. However, both
systems are used by large numbers of photographers to process their
images, so either platform should serve you adequately.
5.1.2
Desktop Versus
Laptop
Today many digital artists—including even music recording
artists—do their computer work using a laptop rather than a
desktop. Though laptops (i.e., portable computers, also sometimes
called “notebooks”) still tend to be computationally
less powerful than
comparably-priced desktops, today’s models seem to be, in most cases,
powerful enough for fairly serious image processing. And most
importantly, they are arguably essential for any traveling photographer
who takes more photos than can fit on his or her collection of memory
cards.
When on any multi-day trip far from home, I always
upload my photos to the laptop each night after retiring from the
field. Once on the laptop, I can then back them up onto multiple
external hard drives, one of which can stay locked up in the hotel room
while the other stays locked in the trunk of my car (to avoid loss of
images if either my hotel room or my car is burglarized the next day
when I’m out in the field). It’s also highly useful to be able to
review a random sample of the images taken that day (in higher
resolution than shown on my camera's LCD), so that I can take
note of anything which is lacking in that day’s photos. For
example, I may find that I’ve concentrated too much on one species of
bird at the expense of other species, or I may find that all of my
photos of a particular species turned out poorly, prompting me to try
harder the next day to obtain usable images of that species. I
may also note any systematic quality issues, deriving either from my
technique or from potentially faulty equipment, which I may not have
noticed while out in the field.
Note, however, that there are some alternatives to
the use of laptops when on the road. A number of smaller, more
affordable devices are available for backing up photos in the field,
some of which also feature a built-in LCD display so that you can
review images. A laptop is simply more flexible, since it can
also be used (if your hotel offers internet connectivity) to check the
next day’s weather forecast, prospect for
alternative birding sites if the main site turned out poor, look up
driving directions, check email, etc. (though many of today’s cell phones can do these things
too).
5.1.3
Memory and hard
drive capacity
Two very important features of any computer system are the memory
capacity and the hard drive
capacity. For the benefit of those
readers still fairly new to computers: the memory (or “RAM”) is the
temporary work space that the computer uses during its processing, when
the computer is turned on. When the computer is turned off, the
contents of RAM are completely lost. In contrast, the
contents of the computer’s hard drive
remain accessible between
sessions, even after the computer is turned off and back on again—just as with the memory cards used
in your camera.
The need for large memory capacity is therefore
dictated by the specific software which you use for image
processing. Some programs are very clever at getting at lot of
work done while using only a small amount of RAM, while others aren’t
so clever and may refuse to complete an operation if they run out of
RAM. The need for large hard
drive capacities, on the other hand, is
largely a function of how many pictures you take (and keep).
Thus, if you
typically do only very minimal processing of each photo (i.e.,
adjusting saturation and contrast) but you take lots and lots of
pictures (and don’t delete many of the ones that you
take), then it’ll be more critical for you to buy a computer with a
larger hard drive than to buy a computer with an enormous amount of
RAM.
Note that RAM and hard drive capacities can (to a
limited degree) be extended by purchasing additional hardware
later. As
an example, many laptops today ship with 1 GB of RAM, but are
expandable to either 2 or 4 GB. Thus, when shopping for a
computer, be sure to inquire as to the maximum amount of RAM to which
the computer can be expanded. Since RAM tends to be a very
expensive component of any computer system, it may make sense to buy a
computer which has only, say, 1 GB of RAM, but which is expandable to 4
or 8 GB, so that in the short term you’ll face a smaller outlay
of cash, but are free to expand the RAM in the future if it becomes
necessary to do so. Just make sure the computer’s RAM satisfies the “minimum system requirements” specified by your
image-processing software.
Hard drives can also be upgraded to
larger-capacity models later, though this tends to be true primarily
with
desktops only. However, in the case of laptops, due to the
possibility of loss or damage, I recommend not using the laptop’s
internal hard drive for long-term storage of photos. For
long-term storage, I keep three
copies of every image, one on each of
three external drives which are locked away in separate locations for
maximal redundancy and protection from fire or theft (or hardware
malfunction). Thus, the laptop’s internal hard drive only needs to
be
large enough to hold a current “working set” of images, where a “working set” comprises copies of only those
images I’m in the
process of working on (i.e., just those I’m currently preparing for
publication or for print).
5.1.4
Gigahertz and
Number
of Cores
In terms of a computer’s “speed”, there are several basic
concepts that need to be understood. First, the work that is done
by the computer is (for the most part) carried out by what is called
the CPU (Central Processing Unit).
When processing an image,
every pixel which is to be manipulated will require the attention of
the CPU at some point during processing. The basic operations of
the CPU—things like adding two numbers or performing other arithmetic
tasks—are each carried out in some (typically) fixed number of clock
cycles (each of which lasts less than a nanosecond). One way to make computers
work
faster is to speed up the clock, by making each clock cycle take up
less time, so that individual arithmetic operations also take up less
time. In this way, the computer gets more work done per unit
time, and as a result, a complete image-processing task that
previously took 30 seconds to complete might now take only 15
seconds. Thus, for a given CPU architecture, a faster clock rate—indicated
by a higher GHz
rating—generally means that more
work can be accomplished in less time. For different CPU
architectures, however, it’s generally not possible to compare GHz
ratings, since one CPU might, for example, require fewer clock cycles
to perform an arithmetic operation than a CPU of another
architecture. This is generally the case with competing CPUs from
Intel and AMD, for
example When comparing two computer systems with two different
advertized GHz ratings, make sure both use Intel, or both use AMD,
before drawing any conclusions based on differences in GHz
rating. If the CPU’s are made by different companies,
then the one with the higher GHz rating will not necessarily be the “faster” machine.
Another complication in comparing today’s CPU’s
derives from the advent of multi-core
systems. In these systems,
each CPU actually has more than one “core” or computing device within
it. In theory, a dual-core
system is capable of doing (roughly)
twice as much work per unit time as a comparable system with only one
core. This assumes, however, that the software being run on that
system knows how to use multiple cores simultaneously, which many
programs in fact do not. The newest versions of Photoshop do, in
fact, support multiprocessing, and can therefore run much faster on
multi-core systems, though it’s advisable to specifically inquire as to
whether your chosen software will support multiprocessing (sometimes
called “multithreading”) on your particular multi-core
system,
especially if your system uses a third-party brand of CPU. Many
of today’s laptops utilize dual-core CPU’s, while high-end desktops may
have 8 or more cores.
5.1.5
Built-in Card
Readers and other Gimmicks
While many laptops feature built-in card readers, making purchasing
decisions based on such gimmicks is ill-advised. External
card-readers (typically USB
or FireWire) are available
very cheaply,
and these external readers typically support far more types of cards
than any laptop is likely to do.
5.1.6
USB Versus FireWire
In the case of laptops, because of their small size, the number of
ports (such as USB or FireWire) available is typically limited.
Furthermore, many laptops feature only USB ports. Because many
external hard drives and card readers utilize FireWire, it’s advisable
to try to find a computer having at least one of both types of
port. As long as your computer has at least one of each, the use
of an external hub can extend
your effective number of usable ports of
either type.
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