Digital Images for Teaching and Learning
For centuries, professors have employed images in their teaching and research. Pythagoras drew diagrams in the dirt. Einstein imagined in his mind’s eye relativity before he developed its mathematics. Our colleagues in art history show slides, chemists model molecules, and physiologists stain slides. Images are essential to teaching and learning in many subjects, and helpful in all. Much more than entertainment or decoration, diagrams and photographs carry the content that cannot be communicated with mere text or numbers.
This session gets you started using digital images in your work. It takes you through the process of capturing images from a digital camera or from the web, organizing and editing them on your computer, and then employing them in a presentation. You will learn to use a digital camera, to search and save images from the web, to employ the iPhoto software, and to incorporate images into a Keynote presentation.
By the conclusion of this session, you will know how to:
- Capture images from a digital camera or from the web.
- Organize and edit images in iPhoto.
- Employ digital images in Keynote slide shows.
- Understand how digital images work.
- Understand how copyright law applies to digital images.
The seminar will be most valuable to you if you plan in advance a teaching or research activity in which images can play a key role. Consider a teaching or research project that can take advantage of digital images. You need not be a teacher of visual art or photography to employ images in your work.
Some say that a picture is worth a thousand words. But the computer disagrees. A single picture takes up between 50 thousand and 6 million bytes of memory, while a thousand words might consume 10 thousand bytes. Words therefore are more efficiently stored on the computer than images, but perhaps less efficient at communicating ideas. However, this all depends on which ideas you are trying to get across. And which pictures you are using.
Many teachers use images of various kinds in their presentations to students. And many students do the same as they prepare and present their multimedia reports. As I watch these presentations, which are becoming more and more popular in schools and colleges, I see my colleagues using images in some very different ways. This week's article attempts to describe the different ways of using images in a presentation, with an eye to the educational value of each method.
I have seen educators use images in their PowerPoints, Keynotes, podcasts, and web pages to decorate, illustrate, illuminate, provoke, compare, contrast, oppose, predict, surprise, and build metaphors. Here's a lexicon of the ways they use images, arranged from the simplest to the most complex.
To please the little second graders, the guest speaker put animated animal images on the slides -- birds and butterflies that cavorted at the corners of the display. These pictures had no relationship at all to the content of the presentation, which was about different types of rocks (he was a geologist from the local university.) He was using the images to decorate his slides. Decoration is the lowest, and perhaps least effective way of using images in presentations. It can also be dangerous. For the geologist, the first question asked by the students at the conclusion of his talk was, "Do those birds live inside the rocks?" Some of the children confused the decoration with the content.
A wise computer artist once advised me that every pixel has a purpose. She warned us against placing visual elements on the screen unless they had a clear communicative purpose. "No decorations, " she insisted. "If you can't explain exactly how that dot or line or circle or little yellow bird helps your audience understand your message, then get rid of it." With today's clip art libraries and colorful templates and borders and backgrounds to choose from, it's very easy to decorate your presentation with images. But it may be more effective to forego the decorations and move up to some of the more powerful uses of images that follow.
This is probably the most popular use of images: to illustrate a point that you are making in your presentation. "Here is an example of a sedimentary rock," said the geologist as the slide showed a close-up photograph some limestone layers in a riverbank. The picture illustrated his message, complementing his words with a visual example that helped clarify what he meant. "See those layers? Each of them was formed from shells and sand falling to the bottom of the ocean."
Illustrative images work best when they add to, and do not simply repeat, what you say or write with the slide. They work best when you use a single large and detailed image on a slide, with little or no text or other information alongside it. This helps the viewer concentrate on the image itself. Don't forget to allow enough time for your viewers to examine the picture, to take in its details and absorb its gestalt.
When you use an image to illuminate an idea that you are trying to get across, you light the way to a deeper understanding. "Let's zoom in on these layers in the limestone. See in this more detailed photo the skeletons of tiny sea creatures that gave up their shells to form this rock." Now the image is essential to the message; without the image, the message is impossible. The picture communicates the majority of the idea, while the presenter's voice carries a minority. Illuminating images go beyond the words, deeper, in more detail, providing additional examples, amplifying and clarifying what the words say.
If the projector bulb burned out as you were about to display an illuminating image, you'd be dead in the water; but with decorative or illustrative images, you could still sail on with voice alone. Illuminating images involve more risk, but engender more learning.
Images in this category can be more powerful than the others. They are designed specifically to cause students to think because of their logic or dissonance. And we mean provocative in the older sense of the word: not shocking or titillating as we are used to in the modern media, but thought-provoking and mystifying, as we see in great visual art. Here are some of the ways teachers use images to provoke ideas in students' minds:
"Take a look at this picture of a sedimentary rock. Now look at this picture. What differences do you see?" The teacher here is using two images to get their little brains working. He displays the images one after the other, or side-by-side, and asks an open-ended question designed to get them to observe, cogitate, and report. Carefully- crafted comparison of images can engage the student in the kinds of thinking he needs to understand the underlying concept. Comparisons can be blatantly obvious or soft and subtle; they can show relationship, order, complexity, development or cause-and-effect.
Similar to comparison, contrasting images are often used by teachers to provoke thinking. Our geologist showed on the same screen a picture of a skyscraper in New York City and a quarry in Ohio, two very different images. "What do these two have in common?", he asked. (Both showed surfaces of limestone.) Visual contrast alone is interesting to the student's mind; contrasting images carefully chosen, along with exactly the right question can set that mind to wandering to new destinations.
The psychology professor teaching about the concept of empathy opened the discussion with a series of photographs of people and animals fighting, making angry grimaces, and doing bad things to one another. "What's missing in these pictures?" was his question. He started from the opposite to reach the idea he was looking for. He helped define the concept by showing examples of what it was not. This kind of backward thinking can be useful in many educational settings.
The psychology presentation proceeds with a sequence of images: an elderly gentleman reading the newspaper as he stands waiting for the bus; his dropping the paper into the puddle at the curb; bystanders noticing his predicament. The teacher asks, "What do you think will happen next?" And more importantly, "Why?" He is using images to get his students to project, extrapolate, think ahead, and predict the next item in the sequence. These sequential images exercise yet a different form of cognition.
A professor of nutrition begins his talk with a close-up photograph that looks like a forest of hollow silver tree-trunks. The audience was expecting a lecture on Nutrition and Public Health in America. We were puzzled as he asked, "What do you think this is?" None of us knew, and our guesses were all wrong. He moved to his next slide, a photo of a polar bear walking across an ice-floe. "What you saw in close-up was the hair of this bear.." He went on to explain how the super-insulating coat of the bear adapted him well to his surroundings, and how the same coat could become a burden under different circumstances -- such as in Florida in August. He used the image of the bear's hair to surprise us, to puzzle us, to get our minds working.
Back to the class on empathy. The teacher shows a pair of well-worn empty shoes on the screen. "What does this have to do with empathy?" He is using the picture to develop a metaphor, a seemingly un-connected concept that sheds light on the topic at hand, and helps students think about it. Images can provoke or develop metaphors in almost every academic field. Our nutritionist went on in his lecture to use the maladapted polar bear in Florida as a metaphor for a human digestive system adapted for an era of scarce food, a system that runs into difficulty when surrounded by plenty. Check out Acclaim Photography for some ideas in this regard. Then develop some image metaphors in your own subject area.
Consider the history teacher who assigned this project to his students:
Compare and contrast the ways of life in your community 100 years ago, with those of today. You should use as many original sources as possible, and must show documented evidence for every point you make in your report.
This assignment doesn't seem to have anything to do with digital images. It looks like a typical history project that has little reference to pictures or computers. But like many assignments, it opens a great opportunity for students to let digital images help to tell their story. For instance, students could…
- find a map of the community from 100 years ago in the library, photograph it, display it next to a current map from the town's web site, and explain the differences.
- take a digital photograph of the downtown shopping area. Then search for a photo of the same area from the beginning of the last century and photograph or scan it. Edit them to be the same size, and display a comparison.
- construct a diagram of the structure of the town government 100 years ago, based on written descriptions in the town history book. Then construct a diagram of the government today, highlighting differences between the two.
- find a picture of the university president, mayor, and governor of 100 years ago. Display them next to photos of today's officials.
This assignment would call for students to do many things beyond gathering and preparing digital images. It is an example of how images can contribute to understanding. Consider how you might develop an assignment or a presentation that employs digital images in your own work.
The World Wide Web is the most common source of images for educational reports and presentations. This activity shows you how to find images on the Web, how to copy and download them, and how to insert them into your iPhoto library. It also discusses the copyright and citation issues that accompany your or your students’ use of these borrowed images.
For our purposes, we will use the word images to refer to photos, drawings, diagrams, logotypes, and other forms of non-text communication. The instructions below are confined to still images; they will not work the same way for video clips, animations, or other forms of moving images.
The chemistry lecturer needs an illustration of the structure of an atom of oxygen, to help students visualize the ionization process. Where might she find such an image to use in her slide show? How might the agriculture student, developing his research on farming in South America, find photos to communicate the contrast between the stacked mountain terraces of Peru and the vast plains of Argentina? Following the standard keyword search method for either topic would garner hundreds of web pages, only a few of which contain any images at all, resulting in a long and tedious search.
A better way is to use the specialized image-searching capabilities of the popular search engines. For instance, launch Safari and connect to the image search page at Google and enter your keywords, such as “oxygen atom” or “fertile plain”. As in any search, the better formed your keywords, the more effective the result. The difference here is that Google will search only for images of oxygen atoms or fertile plains, ignoring pages that contain only text about these topics. The search is much narrower, and thus more relevant to your needs.
The search engine presents you with a gallery of thumbnail images that you can peruse until you find one that suits your purpose. Click the thumbnail, and you connect to the page containing the image. (You may need to scroll down to find the image.) Once you have located an image containing the content you need at the size you need, you are ready to copy or save it.
Warning: No Stretching
Small images form the Web cannot be stretched to fit your slide show without losing their quality. So as you search, reject any pictures that appear on the web page at too small a size. Google's thumbnail gallery shows the size of the images in pixels, which can help you manage this part of the search.
Search and find a half-dozen images that you might use in your own project.
Once you have identified an image from the Web that you would like to use in your project (or simply to save in your iPhoto Library), you need to save a copy on your computer. Using Safari, simply control-click the image (click it while holding the ctrl key on the keyboard), then choose Add image to iPhoto Library from the pop-up menu.
This sends the image to your iPhoto Library. At this point, it's a good idea to go to iPhoto to see it, and to record its citation and other information about it.
Tip: Citation Habits
It’s a good idea to get yourself and your students in the habit of citing the sources of their images. iPhoto and Safari make this easy, but not automatic. Taking a second or two to record where the image came from is well worth the effort.
Find the image you just saved from the Web – it will be at the end of the library. Drag it into the album you just created. And while you are here, enter the image’s citation. Here’s how:
- Open the Information panel by clicking the i button at the lower left of the iPhoto window. In this panel, you can enter a name for the image, as well as other comments.
- Back in Safari, select and copy the URL of the image – that’s the address of the Web page on which it appeared.
- Back in iPhoto, click in the comments area in the Information panel, and paste the URL of the image.
- Notice that the date and time of the saving of the image has automatically been recorded by iPhoto. You now have a solid citation for the source of this image.
- While you are here. Consider adding other comments that will help you locate this image later.
Anything you enter into the comments section can be used later to search and find this image in your iPhoto library.
Some people call all this information about the image meta-data – that means that it’s not the image data itself (the pixels and the colors) but information about the data, such as when it was saved, where it came from, what it’s about, and so forth. This information serves as a catalog entry for this image, enabling it to be located again, and keeping track of its provenance.
You may save as many images as you like from the Web into iPhoto. For this seminar, three or four will suffice.
The images you find on the Web do not belong to you. Therefore you cannot publish them without permission from their owners. But teachers or students may use these images in their educational projects without seeking permission, under the copyright law's fair use provision. As long as they are used for teaching and learning within the school or classroom, they fall under this exemption. But as soon as you move beyond this limited use, such as publishing a textbook, you need to get permission to use the images you get from the Web.
Even though it's legal to use Web images in a school project without permission, it may not be wise to use them without citation. Most schools have academic policies that require students to cite the sources of the quotations or data that they use in their projects. The same rule should apply to images from the Web. As a teacher, you might want to require that the source of every image in your students' projects be listed in a caption or bibliography. So, as indicated in the process described above, it's a good idea to record the URL of each image as you copy or save it from the Web page.
The Creative Commons is part of a movement to revise our notions of copyright and explore some new ways to share the works we author. They endorse a non-profit alternative to standard copyright. You can learn more about the Creative Commons from its web site.
IPhoto is the software application you will use to organize and edit your images. Connect to the QuickTour tutorial on iPhoto.
Read the brief article below on How Digital Images Work, that will provide you some technical background on the nature of digital images.
It's all about pixels. A pixel is a point of light, so small that you can see it only if you look very closely. Images on a computer are divided up into a grid of thousands of little tiny pixels. In the computer, each pixel is stored as a series of numbers that indicates its color, as a combination of red, green, and blue light. So a bright red pixel would be stored in the file as 200-60-44 – that’s 200 units of red, 60 units of green, and 44 units of blue. Similarly, a bright blue pixel as 56-78-204. The image file is simply a long series of numbers, one pixel after the other. A typical quarter-screen image would contain 76,800 pixels, and so its file would consist of 76,800 numbers.
The bigger the image, the more pixels, and the longer the string of numbers. Your computer displays about 72 pixels per inch, so a picture one inch square contains 72 x 72 or 5,184 pixels. A picture that filled your computer screen would contain of 800,000 pixels. Such a picture would produce a huge string of numbers, and thus a very large file on your disk. In fact, such a picture would be so large it would not fit on a floppy disk.
Your computer displays 72 pixels per inch. A printer can display over 300 pixels per inch. A television screen can show about 20 pixels per inch. A good digital camera can capture 1000 pixels per inch. That's why you can see more detail on paper or on a photograph than you can on a computer screen or television. This number of pixels per inch is called the resolution of the image. The higher the resolution, the more detail you ca see, but the bigger the file. For most educational projects designed to be shown on the Web or to be projected in class, a resolution of 72 pixels per inch works best, and results in smaller file sizes that are easier to work with.
The only time you might need to use a higher resolution is when your work is going to be published on paper with a high-quality printer, and when the extra detail is necessary. Since most projects will be displayed on a computer, you're best to prepare all your images at a resolution of 72 pixels per inch.
When you save pictures from the Web, or transfer them from a digital camera, you will notice a three-letter extension to the filename, such as .jpg or .gif. These filename extensions indicate the file format of the image. Most photographic images are stored in the JPEG or .jpg format, and most drawings are stored in the GIF or .gif format. JPEG (pronounced jay-peg) stands for Joint Photographer Expert Group, and this file format was invented by a group of photographers. GIF (pronounced with a hard G) stands for Graphics Interchange Format and was invented by the Compuserve company back in the early days of the Internet.
Other formats are used for images, such as PNG, EPS, TIFF, PICT, and BMP. But the most commonly used are JPEG and GIF. iPhoto can work with most of these file formats, but it's best to save your images in the JPEG or GIF formats when you have the choice, because these can be read by just about every computer and software program, and they create small files.
JPEG and GIF are compressed file formats – they do not save every number from every pixel – and so the files are smaller. Compression works by mathematic formulas that examine the string of numbers in an image file looking for repeated numbers – such as a large patch of blue sky whose pixels are all the same color – and reducing them to a special code. These compression algorithms also average adjacent pixels of similar color to produce even more repeated numbers. The result of this data compression is a much smaller file that when decompressed looks almost as good as the original.
The pictures from a digital camera, or from the Web, are already compressed in most cases, so you need not worry about making adjustments. Should you need to compress an image in a special way, you may use iPhoto’s Export feature to do so.
The digital still camera has become the technology par excellence for capturing images for use in multimedia teaching and learning. The cameras are easy to use, but it's not so easy to get a good-quality image that will enhance your project. These guideleines can help you capture a quality image. As you shoot pictures, follow these guidelines:
Light: A brightly-lit subject will photograph better than one that is in the shadows. Shoot the picture with the source of light behind the camera. Arrange the subject so that the light doesn’t shine directly onto them, but at an angle. This keeps people from squinting, and provides pleasant shadows to show off texture and detail.
Tight: Let your subject fill the frame. In a group shot, crowd the people very close together. Avoid groups of more than five. Include only heads and shoulders in the photo. For buildings or rooms, you don’t need to include the entirety; often a close shot of one interesting part of the room or the building looks better.
Sight: The camera sees not only your subject, but what’s behind it as well. Shoot pictures against a plain background (but don’t back people right up against the wall -- keep them three feet away). Remove distracting details from around the subject of your picture before shooting.
Write: Words do not show up well in pictures. It’s almost impossible to read text from a photo on the Web. Use photos for people, buildings, and events; use the written part of the page for words. Those nice letters on the sign may be readable through the lens of the camera, but they will be indecipherable on the computer screen.
Uptight: People seem more alive when they are not posing. If two people are in a picture, ask them to talk, or to show one another an item, rather than to stare into the camera. Getting them to do something will help them relax, and make a more “human” photograph. Photograph people actually doing their work, rather than standing in a pose.
For an interactive illustration of these concepts, click the illustration, above right.
--> Shoot three or four images for this project.
To get the images from the camera to iPhoto, simply connect the camera to your computer with its USB cable. This will automatically launch iPhoto, and initiate the process of copying the images from the camera to the computer. The images will be saved to the Last Roll album in iPhoto, whence they may be dragged to your project album. As you did with images from the web, it’s a good idea to enter a useful title and some comments that will help you retrieve the image later.
Your album now contains six to eight images. You may use iPhoto to reorder these images in the window (simply drag them to where you want them), to rotate them so they are right side up (use the rotate button).
You may also organize your images with iPhoto, by using keywords. In iPhoto, keywords are categories that you may assign to images. To set up your keyword list, from the menubar choose iPhoto --> Preferences, then click the Keywords tab. Add your own keywords, relevant to your work, to the list.
- To assign a keyword to an image, select its thumbnail, then from the menubar choose Photos --> Get Info, then click the Keywords tab. Select any keywords you want to apply to this image. Do the same if you like for the other images in your project album.
- To display the keywords in the thumbnail gallery, from the menubar choose View --> Keywords. In like manner, you may also choose to display the titles of the images.
- To sort the photos in various ways, choose from the menubar View --> Sort, then your desired sorting criteria (Title, Date, Keyword, or rating).
Not all of your images will appear exactly as you’d like. To edit an image in iPhoto, select it and click the Edit button. The picture will fill the window, and you may crop it, or adjust its parameters.
- To crop, click and drag the mouse to select the portion of the image you want to keep, and then click the Crop button.
- To perfrom a quick, automatic adjustment, click the Enhance button.
- To adjust manually, select the Adjust button. This opens an adjustment panel with a set of sliders that enable you to change the brightness, contrast, color balance, and sharpness of the image.
- To apply effects to the image, click the Effects button.
If you make an adjustment you don’t want to keep, you may choose from the menubar Edit --> Revert to Original. When your adjustments are complete, click the Done button at the lower right, and the changes will be saved with the image.
The result of all this work with images is more than a collection – it’s a source for enhancing presentations and reports. From iPhoto, you can insert images into most standard applications such as Keynote (for slide shows), Pages (for printed documents), iWeb (for web pages),vGarageBand (for podcasts), or iMovie (for videos). These instructions show how to use images in Keynote; a similar process applies with other applications. Follow these steps:
- Launch Keynote and choose a theme.
- On the first slide, enter a title for your presentation.
- Add a new slide by choosing from the menubar Slide --> New Slide.
- Open the media browser by choosing from the menubar View --> Show Media Browser.In the Media Browser, select the iPhoto tab at the top, and find your album in the list.
- Drag a photo from the media browser to the slide.
- Adjust the size and location of the image by clicking and dragging its handles.
- Repeat steps 3 – 6 for additional slides.
- Save your presentation.
- View your presentation by choosing from the menubar View --> View Presentation.
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