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Digital photography

Autor /Olivier Dodano /10.11.2011

Digital - this is one of the most popular word used when we talk about new technologies and computers. Everything nowadays is digital. but what exactly this means? Let's look closer at the definition for it.

Digital, related to digits or the way they are represented. In computing, digital is virtually synonymous with binary because the computers familiar to most people process information coded as combinations of binary digits (bits). One bit can represent at most two values; 2 bits, four values; 8 bits, 256 values; and so on. Values that fall between two numbers are represented as either the lower or the higher of the two. Because digital representation represents a value as a coded number, the range of values represented can be very wide, although the number of possible values is limited by the number of bits used.

Digital photography and digital camera, this is the topic of my paper. In order to talk about digital photography we need to define photography in general.

Photography is a technique of producing permanent images on sensitized surfaces by means of the photochemical action of light or other forms of radiant energy. In today's society, photography plays important roles as an information medium, as a tool in science and technology, and as an art form, and it is also a popular hobby. It is essential at every level of business and industry, being used in advertising, documentation, photojournalism, and many other ways. Scientific research, ranging from the study of outer space to the study of the world of subatomic particles, relies heavily on photography as a tool. In the 19th century, photography was the domain of a few professionals because it required large cameras and glass photographic plates. During the first decades of the 20th century, however, with the introduction of roll film and the box camera, it came within the reach of the public as a whole.

Today the industry offers amateur and professional photographers a large variety of cameras and accessories. Now in our new era of fast developing new technologies traditional techniques are being replaced with new- digital one. New technologies are beginning to blur the lines between photography and other image-making systems. In some new forms of still photography, silver-halide emulsions have been replaced by electronic methods of recording visual information.

Digitization of photographic images has begun to revolutionize professional photography, giving rise to a specialized field known as image processing.

Digitization of the visual data in a photograph-that is, conversion of the data into binary numbers using a computer-makes it possible to manipulate the photographic image by means of specially developed computer programs. The Scitex image-processing system, the commercial and advertising industry standard in the late 1980s, enables the operator to move or erase elements in a photograph, to change colors, to fashion composite images from several photographs, and to adjust contrast or sharpness. Other less sophisticated systems, such as Macintosh's Digital Darkroom, allow similar operations. The quality of computer-generated images was, until recently, inferior to strictly photographic images. Most nonindustrial color printers and laser printers cannot yet produce images with the tonal range, resolution, and saturation of photographs. Some systems, however, such as Presentation Technologies' Montage Slidewriter and the Linotronic system, are capable of producing magazine-quality images.(1998).

Let's take a closer look at how digital photography works. In a digital photography the details of a scene are recorded as numbers. Each tiny region of the original scene is recorded as a number. Thus, a scene recorded in a digital camera doesn't in any way resemble the original scene the way the image on film mimics the original scene. Rather, a digital image is just a series of numbers - for example, 14,372...64,285...3,985...etc. How is the image reproduced to look like the original scene?

That's the job of the computer and the software program. It recreates the appearance of the original image by translating the meaning of the numbers back into a pattern of light and color.

How is the number-information recorded in a digital image? Film uses silver-halide crystals to record the image. In the digital world, the image is recorded on a chip of silicon. Here's what a chip looks like:

The light-sensitive chip is only the bright rectangle in the middle of this device. The first thing you notice is that the chip looks very small in this picture. Actually, this is the real-life size of a typical chip used in one of today's consumer cameras. Chips are expensive. And big chips are very expensive. So you will get a small chip, about this size, in a typical consumer camera - that is, in a camera that we arbitrarily define as costing less than a thousand dollars. If we were to enlarge this chip so we could see detail on it, we would see the surface of the chip is composed of tiny dots. Each dot is the equivalent of a grain of silver-halide in your regular film. Only the dot on the chip is silicon, not silver halide. Each dot of silicon on the chip is light-sensitive and it records information about the light it receives from a tiny region in the original scene. What it does is convert the light into electrons. The stronger the light, the more the electrons. These electrons are then "counted" by another computer-chip in the digital camera, which converts them into a number.

The first chip - the light-sensitive chip - is what we call a CCD-that is, a charge coupled device. The important point to remember is that a CCD is a chip that has a large number of tiny dots of silicon on its surface. Each silicon dot has the unusual property of being sensitive to light so that it converts the light that strikes it into a tiny electric current that is fed to another computer-type chip in the digital camera which converts it into a number. In effect, the intensity and color of the light that strikes each silicon dot on the CCD chip is "remembered" in the camera as a number.

How much information can a chip record?

We know that each 35mm frame of kodachrome contains billions of microscopic grains of silver-halide, each of which records a "microscopic" bit of information about the original scene. So a 35mm frame of kodachrome can record billions of bits of information. What about a silicon chip? This is a limitation of digital photography today. The silicon chip in a typical consumer digital camera can only record thousands of pieces of information - at most, hundreds of thousands. Not millions or billions. Only thousands! Clearly, then, when it comes to rendering a real-life scene in all its infinite glory, digital photography today doesn't come close to matching the detail you can get on regular film. But, before you start dancing around the ashes of the digital camera, realize that perhaps the most important word in the previous sentence is the word, today. Digital-imaging technology is moving fast. What is true today will not necessarily be true tomorrow. As we said before, some gurus say that film will be "dead" in just a few years. Others say that digital photography will never match the detail recorded on film.

And most industry bigwigs say, "Not now...but eventually!"

In what ways is digital photography superior to film today?

If image quality were the only measure, this entire Primer would be premature if not downright unnecessary. But image quality is only one criterion. What about sending an image over the phone? You can't easily do that with a film image. But you can with a digital image. Why would you want to send a picture by phone? One reason might be to let Grandma see your new baby just minutes after he's born. But the quality of the digital picture is not as good as the film-picture she'll get in the mail in about a week. So what? Do you think Grandma will care?

Another advantage of digital photography today involves newspaper pictures. Already, some newspapers require all their photographers to use digital cameras. Why? So that the latest on-the-scene pictures can be sent to the paper by phone without delay. Now, for example, the morning paper can publish pictures of last night's extra-inning Big League game, instead of having to wait for the next edition - often, a day later. What about the quality of the digital image? It's more than good enough for ordinary newspaper reproduction. As you know, newspaper images are printed as a series of black or colored dots and, at their best, are not very sharp. Images produced by digital cameras are also a series of dots. And they're more than good enough for newspaper reproduction.

What about posting an image on your Website? You can't do that with a film image (at least, not directly). You can with a digital image. You send the image in a digital format to the Website, where it is converted by software back into the original image. Is the digital image good enough for presentation on the web? Again, you know that your computer screen is composed of rows of dots that convert electric current into light and color. The image from a typical consumer digital camera today has more dots of information than you'll find on the computer screen. So, again, the digital image is more than good enough.

What about seeing a picture a moment after you shoot it? In traditional photography you need to develop and process film. (Even Polaroid instant prints require development and processing - albeit, this is handled by the camera quickly and internally.)

Digital images don't require any "wet" processing. You snap the shutter of a digital camera, and within a few seconds you can see the resulting image on the small screen that's on the back of most consumer digital cameras. Moreover, if you don't like the picture you see, you can erase it with a click of a button on your camera, and take another. You get instant feedback! And you avoid paying good money to see "bad" pictures.This is another advantage of digital cameras today.

What about never again having to pay for film...or processing...or printing?

These are all expensive with a regular camera. With a digital camera you completely eliminate the cost of film. You also completely eliminate the cost of processing. And you reduce the cost of printing - though printing your digital pictures can still be expensive.

Picture what a boon digital photography can be to a real estate broker.

Let's say she's in Seattle. Her client is in Boston, and he wants her to find a house for his entire family near Microsoft headquarters in Redmond, Washington. The broker hops in her car and travels around Redmond and the nearby Seattle suburbs. She photographs houses that she thinks he might like. If the broker uses a traditional camera, she has to buy film, have it developed and printed, then mail the best pictures to the client in Boston.

Even if she uses a one-hour lab, the pictures may still not get to Boston for a week as they travel by mail! On the other hand, if she takes the pictures with a digital camera, she can download them into a computer the moment she returns to her office, and the client in Boston can see them instantaneously either on a Website or at his e-mail address. In addition, she has no cost for film, processing, or printing. (In this case, she doesn't have to print the images; she merely downloads them into a computer.) The entire procedure is virtually free. Are her digital pictures clear enough for this purpose? You bet. While they may not win any prizes at the local Photography Club, they're plenty good for the client in Boston.

With a usage of a digital camera you can also do things like cropping the image, eliminating the background or changing it completely, and printing the changed image on a magazine cover. Can you do any of this in a traditional darkroom? Not easily. But in a digital darkroom it's a snap. It takes just a matter of seconds, not hours. And you don't wet your hands or stain your clothes. There's a lot to be said for that!

Is a digital camera better than a film-based camera?

Better for what? A knife is better for some jobs, like slicing bread or whittling a stick. A scissors is better for other jobs, like making paper cutouts or shearing hedges. So, too, a filmbased camera is better for some jobs, like taking really detailed pictures - especially, pictures you want to enlarge. And a digital camera is better for other jobs, such as sending pictures over the phone to Grandma or to a Website.

There's no "right" camera for every job. What makes digital photography so exciting - today! - is that it opens whole new worlds to you - worlds that are parallel to, not substitutes for, your regular film-based photography.

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