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 todays 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 againjust 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 Im 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 CPUs 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.