Everyone is talking about
Digital Imaging Technology. Everywhere you look, digital still and
video cameras are for sale, and
all of your techie friends either have one or intend to get one. But what exactly is digital imaging? How does a digital camera work? How does one get started?
The basics
Digital Imaging is just a fancy way of saying that you are capturing pictures in a digital format. The main difference between digital and film photography is in how the image is captured and stored. One way of looking at the technology is to compare it to music recording. Both pictures and music are very complicated analog images, one of light, one of sound.
Music used to be recorded as a direct copy of the sound; that is, the music was captured in its exact sound-wave form in the shape of a wavy groove in a vinyl disk, or as a fluctuating magnetic field on a piece of metal (oxide)-particle-coated tape. The resulting signal had the same waveform as the original music.
For example, to illustrate the direct analog nature of such a recording, you can play back any vinyl record by simply placing a pin stuck through a paper cup into the groove. The wiggles in the groove create vibrations of the pin, reproducing the sound, with the cup acting like the old horn speaker on a victrola. Since the music was recorded into the vinyl as a direct analog waveform, the sound can be read directly out of the groove.
A digital music recorder takes that same acoustic wave and divides it into thousands of little pieces, assigns a numerical value to each micro-slice of sound, and records the music as a string of numbers. The advantage is that once you have turned the music into computer data, you can store, edit, copy, and play that music more easily, and with a greater accuracy than an analog system. You can even compress the music data using computer storage methods, so you can fit lots of music into a small space, or send that music through the Internet.
Photographic (and by extension, movie) analog image capture uses a sheet of paper or plastic coated with light-sensitive chemicals (film) to obtain the image. The light from the subject is focused on the film, which then changes according to how much light and what color the light is. This change is “fixed” with developing chemicals, providing an exact image what of the camera “saw”. This picture is a direct representation of the light that fell on the film.
Digital photography replaces the film with a silicon chip covered with photodiodes representing the various bits of the image, called pixels, that it is made up of. These pixels turn the light information into a number that when translated and combined, creates the image. The picture resolution is determined by the number of pixels in the image. A 1.5-Megapixel image, has 1,500,000 pixels, which for example's sake we'll say are arranged in a grid of 1,500 x 1000 pixels. The more pixels, the better the image. Again, being essentially computer data, the picture can now be edited, and even altered, on a computer, and sent across the street or around the world via the Internet or as a file on a floppy disc, CD, or flash memory.
Digital data, being only a numerical representation of the original, cannot be read back directly, but must always be converted back into analog data first. That is why every consumer digital device has to have analog-to-digital (for recording) and digital-to-analog (for playback) converters.
The primary difference is in the end result. As I explained earlier, film cameras give us a direct image on film, and a digital camera gives us data representing the image. All other differences are moot. Every camera today has a digital equivalent, from movie to point-and-shoot to Single-Lens Reflex (SLR) and medium-format cameras. Soon, you will even be able to buy disposable digital cameras that you throw away when the battery runs out, or that become their own dedicated storage device for their pictures when you are finished.
Image Storage
A digital camera stores its pictures on a memory chip. In inexpensive cameras, the chip is internal, and pictures have to be downloaded through a cable. In middle-level cameras and up, removable memory cards store the images for easy transfer of data. These cards plug into standard industry sockets in laptop, PDA, and Desktop computers.
There are several memory card standards. It is important to ensure that you get a camera with the format you want or need. The basic types of memory card include Compact Flash, which is roughly the size of a book of matches, XD Memory, which is a little smaller, SmartMedia, which is the size of a large postage stamp, the SD Memory Card, which is a little smaller and a tad thicker, and the Memory Stick, which is the size of a stick of chewing gum. They all hold about the same amount of data (Except for the Memory Stick, which doesn't hold as much as the others.) For the most part, the type of memory the camera uses isn’t important, as you can get adapters and cables to transfer the pictures into just about any computer or PDA.
Each format has its backers. The Memory Stick is a Sony device, and almost everything they make will take it. Panasonic is a big backer of the SD Memory Card, and the same applies to Panasonic devices and the various companies that ride its coattails. A lot of Kodak cameras have Compact Flash cards, and Fuji and Olympus are the backers of XD Memory.
The question of what memory format to use raises itself when you already have a device that uses removable memory, or if you have a device that can only handle one form of memory. In the case of transfer to a laptop, most removable memory can be inserted into a PCMCIA card adapter. PCMCIA is the standard for interface cards in laptops, and even the smallest laptop (as well as some PDAs) has a slot for such a card. For desktops, you can either use a cable, usually supplied with the camera, or you can buy a desktop reader for the memory card. Many adapters and readers come with aftermarket memory cards, so you can kill two birds with one stone when shopping, picking up more memory along with the device to read it. Having multiple cards is an advantage because you can then use them like rolls of film, changing one out when it gets full. This is useful especially if you don’t have access to download your pictures into a computer in the field.
It’s the result that counts.
Remember, the primary difference is in the end result, the image. The easiest and cheapest way to get digital pictures in a snap is to buy a disposable film camera, and have it developed with a Photo CD provider. Then your pictures will come on a CD-ROM, to be viewed, manipulated, and printed like a digital image from any digital camera. You can get Photo CD’s from any film camera, giving you the flexibility to slowly change over from film to digital by using your current camera to create film that you convert when developed to digital pictures. This way, you can still get the hang of working with digital photos before making the investment in a digital camera.
Another advantage to digital is that you can sort your pictures in the field. You can review pictures as soon as you take them with most digital cameras, and dump bad ones. This is tremendously empowering, and maximizes your photo effort by allowing you to keep only the good shots. Once upon a time, you had to shoot a couple of rolls of film, especially if you were shooting for publication, in order to ensure (and sometimes not even then) a good shot. A digital camera with an LCD screen lets you look at the picture you just shot, and erase any bad shots, shooting until you have the shot you want. This extends the flexibility and range of your photography tremendously. Also, there are no bad prints to throw away!
Once the pictures are taken, you can transfer them to a computer. Once you have transferred your pictures (or video) to the computer, you can use sophisticated software to crop, clean up, and adjust the picture. For example, you can make a change as small as removing people's red eyes from pictures, or a change as major as swapping the head of your subject with that of a cat’s for artistic effect. You can put different backgrounds in,, remove or add people, place unusual items into the picture with your subject, and so on. If you can imagine it, you can alter a digital image to look like it. (That's why you can't trust photos anymore, but that's a different subject.)
Printing digital photographs
Print quality is directly related to resolution. Paper (Currently) has a much higher potential capacity for resolution than your computer screen does. Pictures that look great on your computer screen may look terrible on paper if you aren’t careful. A 2 megapixel image is a file of about 500 kB, and prints out to nicely to a 5x7 photo-quality image. Larger than that, and the pixels start becoming visible, making the picture look grainy. The lower the resolution, the smaller the picture that you can print with good quality.
Once you get the picture you took with your digital camera to look the way you want, it is time to print it out. There are many ways to do this. The easiest way to go is to download the picture to a floppy disk, and take it to an office-service center like Kinkos. These places do photocopying and other business services for small and home offices. They can print out your photo to almost any size for a reasonable price. Some photofinishing shops can also print out digital pictures for you. They usually identify themselves as such, or you can just ask. An additional way to print digital images are at self-serve kiosks. They can be found at many drug stores and photo shops, and will accept a flash memory card or floppy. Not yet very widespread, they are spreading rapidly.
Of course, printing digital photographs yourself is the most convenient way. Doing your own printing gives you a great deal of flexibility, and of course you can use the printer for other chores as well. But what kind of printer should you buy? Luckily, today’s major name-brand printers differ little in print quality. There are major differences in color saturation, resolution, and register (how the dots of ink line up to make the image), but the image output of isolated printers from the various major brands all look acceptable.
Print quality is most apparent when comparing prints side-by-side. This is not to say that the quality isn’t important, but to say that you shouldn’t get too paranoid about it. For example, just about any ink-jet printer you buy from a major brand manufacturer in the $200-300 price range will have photo-quality output. Even a $150 printer can give you great prints. If you want to go higher, a dye-sublimation printer will cost more, but give you correspondingly better prints. It uses solid pigments that it transfers to the paper using heat.
The biggest difference between printers these days isn’t the print quality, but long-term cost, system flexibility, and output speed. A $300 printer will print faster than a cheaper model. If rapid output isn’t important, get a less-expensive printer, and be prepared to wait for your prints. The more expensive printer will also have a greater flexibility as to what kind of input it can take. Some printers have slots for camera memory cards, so you could actually shoot and print digital pictures without a computer, or use the printer for a quick proof-sheet without having to go through the effort of transferring and manipulating images. Printers (and computers, and cameras) with Bluetooth or WiFi (also known as 802.11a/b/g)capability can communicate wirelessly with one another.
Operating cost is another factor. In order to print in multiple colors, a printer mixes the three primary colors to get the desired result. To get black, the printer can either mix it using all the colors, or maintain a separate black ink cartridge. A separate black cartridge is the better way to go, especially if you print a lot of text. New ink cartridges can cost as much as $50 for a set, so keep that in mind when you are printing multiple pictures because you didn't quite like the last one. Proper preparation prevents piss-poor performance. Edit your work before printing.
Film is now in that transitional phase that vinyl records went through when the CD was introduced. Soon film will only be for the dedicated hobbyist and professionals who wish to capitalize on film's creative aspects. Digital is the future, and it’s knocking on your door right now.