2 What Is A Digital Photograph2. WHAT IS A DIGITAL PHOTOGRAPH? (Based on the writing of Dennis P. Curtain A Short Course in choosing & Using A Digital Camera Pixels-dots are all there are. Image size This lesson is about digital cameras and the photographs they capture. Understanding the end product, the digital photograph, is a good place to begin understanding the whole digital photography process. Pixels-dots are all there are.. Digital photographs are made up of hundreds of thousands or millions of tiny squares called picture elements-or just pixels. Like the impressionists who painted wonderful scenes with small dabs of paint, your computer and printer can use these tiny pixels to display or print photographs. To do so, the computer divides the screen or printed page into a grid of pixels. It then uses the values stored in the digital photograph to specify the brightness and color of each pixel in this grid-a form of painting by number. Controlling, or addressing a grid of individual pixels in this way is called bit mapping and digital images are called bit-maps.
Image size
The quality of a digital image, whether printed or displayed on a screen, depends in part on the number of pixels used to create the image (sometimes referred to as resolution). More pixels add detail and sharpen edges. If you enlarge any digital image enough, the pixels will begin to show-an effect called pixelization. This is not unlike traditional silver-based prints where grain begins to show when prints are enlarged past a certain point. The more pixels there are in an image, the more it can be enlarged before pixelization occurs.
The photo of the face (right) looks normal, but when the eye is enlarged too much (left) the pixels begin to show. Each pixel is a small square made up of a single color.
The size of a photograph is specified in one of two ways-by its dimensions in pixels or by the total number of pixels it contains. For example, the same image can be said to have 1800 x 1600 pixels (where "x" is pronounced "by" as in "1800 by 1600"), or to contain 2.88-million pixels (1800 multiplied by 1600).
This digital image of a Monarch butterfly chrysalis is 1800 pixels wide and 1600 pixels tall. It's said to be 1800x1600
WHY GO DIGITAL?CONTENTS Free photography, photographic freedom The three steps of digital photography
Once captured, digital photographs are already in a format that makes them incredibly easy to distribute and use. For example, you can insert digital photographs into word processing documents, send them by e-mail to friends, or post them on a Web site where anyone in the world can see them. With many cameras you can immediately see your images on a small LCD screen on the back of most cameras, or you can connect the camera to a TV and show them much like a slide show. Some cameras can even be connected to a microscope to display dramatically enlarged images on a large-screen TV. Digital photography is instant photography without the film costs!
A small digital camera is easy to carry so you'll have it when you see things you never expected to see.
If you're considering going digital, here are a few more reasons to get even more serious. Going digital saves you money in the long run by not buying rolls and rolls of film and paying for development. It saves you time because you don't have to make two trips to the store to drop off and then pick up your pictures. Digital cameras instantly show you how your pictures look so you'll no longer have those disappointments a day or two later when your film is developed. You can view images before they are printed and if you don't like what you see, edit them to perfection or delete them. Digital photography doesn't use the toxic chemicals that often end up flowing down the drain and into our streams, rivers, and lakes. No more waiting to finish a roll before having it processed. (Or wasting unexposed film when you can't wait.)
Once you have captured an image in digital format, you can easily distribute, organize, store, and edit it. Digital cameras are becoming more than just cameras. Some digital cameras are capable of capturing not only still photographs, but also sound and even video-they are becoming more like multimedia recorders than cameras. In addition to displaying and distributing photographs, you can also use a photo-editing program to improve or alter them. For example, you can crop them, remove red-eye, change colors or contrast, and even add and delete elements. It's like having a darkroom with the lights on and without the chemicals. Free photography, photographic freedom
Although it's both the immediacy and flexibility of digital photography that has made it so popular, there is one aspect that is rarely mentioned. This is the new freedom it gives you to explore creative photography. In the 1870's when William Henry Jackson was carrying 20 x 24 glass plate negatives around the West on a mule, you can bet he hesitated before he took a photograph. We may not be carrying window-sized glass plates, but you and I also hesitate before taking a picture. We're always doing a mental calculation "is it worth it?" Subconsciously we're running down a checklist of costs, times, effort, and so on. During that "decisive moment," the image is often lost or we fail to try new things. We lose the opportunity for creative growth and choose to stay with the familiar that has delivered for us in the past. Surprisingly, Jackson had one big advantage we've lost over the last century. If an image didn't turn out, or if he was out of glass plates, he could just scrape the emulsion off a previously exposed negative, recoat the plate, and try again. Digital photography not only eliminates that nagging "is it worth it?" question, it also returns us to that era of endlessly reusable film (and we don't need a mule to carry it). Hand the camera to the kids, take weird and unusual angles, shoot without looking through the viewfinder, and ignore all previously held conceptions about how to take photographs. You may be surprised at the photos you get if you exploit this new era of uninhibited shooting.
A mule carries William Henry Jackson's photographic outfit. Courtesy of the Library of Congress. The three steps of digital photography Digital cameras are just one link in a long chain leading from the original scene through to the final image that you display or distribute. In fact, a digital camera isn't even an absolutely necessary link in the chain. The key element in digital photography is an image in a digital format made up pixels. Although a digital camera captures photos in this digital format, you can also scan slides, negatives, or prints to convert these traditional images into the same digital format. To understand how the camera fits in with other parts of the digital photography system, it helps to understand the three basic steps involved in creating and using digital photographs-input, processing, and output.
Step 1. Inputting photographs Input devices get photographs or other data into a computer system. The input device you're probably most familiar with is the keyboard. However, there are hundreds of other input devices including mice, touch pads, voice recognition systems, scanners, and so on. Here are some of the input devices you can use to create digital photographs: Digital still cameras capture photographs in a digital format. Film cameras capture photographs on slides, negatives, or prints which you can then scan to convert them to digital photographs. Video cameras capture images in a video format. You can then use a frame grabber to isolate out individual frames and save them as still images. Digital video cameras sometimes are able to capture still images just like a digital still. You can also use a video-editing card to extract still images from the digital video. Step 2. Processing photographs Once a photograph is in digital form, you can store it on your system and then edit or manipulate it with a photo-editing program such as Photoshop. The things you can do to a digital image are almost endless. In some cases you improve an image by eliminating or reducing its flaws. In other cases, you adjust an image for other purposes, perhaps to make it smaller for e-mailing or posting on a Web site. Finally, you might take an image to a new place, making it something it never was. Here are just a few of the ways you can process images: Crop the photograph to emphasize the key part. Reduce the number of pixels in an image to make it smaller for posting on the Web or e-mailing. Use filters to sharpen it or even make it look like a watercolor or oil painting.
With just a few keystrokes, a photo of a mission outside of Tucson, Arizona is made to look like a watercolor. Stitch together multiple frames to create panoramas. Merge two images to create a 3D stereo effect, or an animated image for display on the Web. Change brightness and contrast to improve the image. Cut and paste parts of one image into another to create a photo montage. Convert the photograph to another format. 
Step 3. Outputting photographs Once an image is the way you want it, you can output it to share with others. There are lots of ways to display and distribute digital photographs. Here are some of the most popular ways: 1. Print the image on a color printer or send it to an on-line service to print it on silver-based paper just like that used with film cameras. 2. Insert the photograph into a word processing or desktop publishing document. 3. Post the photograph on a Web site or a photo network. 4. E-mail the photograph to friends or family members. 5. Send the photo to a service on the Web for specialty printing onto T-shirts, posters, key rings, mouse pads, even cakes and cookies. 6. Store the photograph on your system for later use. 7. Use a film recorder to convert the photograph into a slide that you can project with a slide projector. If you've been wondering digital photography is spreading faster than a kudzu vine, here are just some of the reasons. Immediately review your images on the camera's preview screen. Be more confident because you can check your pictures immediately to see if you got what you wanted. Connect the camera to a TV and show your images as a slide show. Connect the camera to a microscope to display dramatically enlarged images on a large-screen TV. Stitch together panoramas from multiple pictures of the same scene. Print the image on a color printer. Create 3D stereo images to display on the screen. Create animations to display on the screen. Save money by not buying rolls and rolls of film and paying for development. Save time because you don't have to make two trips to the store to drop off and then pick up your pictures. Choose just the best images for printing. Be an environmentalist by not using the toxic chemicals used in traditional photography. Don't wait to finish a roll before having it processed. (Or waste unexposed film when you can't wait.) Capture sounds and even short videos with the same camera. Improve or alter your images with a photo-editing program. Hand the camera to the kids, take weird and unusual angles, shoot without looking through the viewfinder. There are no film costs to think about. Insert the photograph into a word processing or desktop publishing document. Post the photograph on a Web site or a photo network. E-mail the photograph to friends or family members. Send the photo to a service on the Web for specialty printing onto T-shirts, key rings, mouse pads, even cakes and cookies. Store the photograph on your system for later use. Use a film recorder to convert the photograph into a slide that you can project with a slide projector. Questions to be answered on #2 Digital Imaging
1) What is a digital photograph made up of? 2) What happens when you use more pixels to make up your photograph? 3) What is pixelization? 4) 4. How is the size of a photograph determined?
5) Give three reasons why you should go digital 6) Name three things you can do to a digital image or in other words process it. 7) Name three ways you can distribute your digital image? Practical Assignment 2Take a series of 6 pictures that clearly show me a letter of the Alphabet. Put them into a folder with your answers to the questions for reading #2. Examples: The letter “O” 
The letter “E”
The letter “X”
The letter “I”
The letter “B”
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