Remember the old Chinese proverb . . . something about hearing and forgetting, seeing and learning, doing and remembering. Well, Imaging in Education covers two of the three sayings . . . the sayings that count the most.

Who of us involved in teaching has not struggled to make difficult concepts simple and easy to understand. And who, involved in this struggle has not turned time and again to visualizing information as an obvious solution: a solution that offers a way to see the unseen. This revealing the unseen is a fundamental tenet of Imaging in Education.

The comical retort . . . "Do I need to draw you a picture?" is an appropriate example of a natural tendency of our species to be primarily visual. We start in kindergarten with the daily calendar. Day, date and brown leaves for October. Hey, it works, so we do it.

The primary grades are full of visual information conveyances. Big books, flash cards, the multiplication tables and clocks; singing, dancing, tying your shoe, blocks, and throw the ball junior. In the middle school years, the skeleton in the lab closet, the Mercator effect, atoms (when will it be Gluons?), stars, planets, cell models and Newton's law. It is no secret to great teaching that to see an object does wonders for the transfer of ideas. These points establish the concept of visualizing information as a common educational technique.

This is the point I want to hammer home: visualizing information is a normal way for the species to go about the business of discovery. Imaging in Education, the subject I am introducing, simply adds to the mix, the capabilities of the computer to manipulate images in the service of understanding.

As fascinated as I am with how things work, I am going to give you the condensed version of the fundamentals of Image Processing in Education. If you are inclined to this same fascination, check out the following book list.

Computers only see what they see digitally. And images, digital images are no more then a string of numbers. Those numbers control what the computer displays on your screen. The computer shoots electrons at the back of the screen. Painted on the back of the screen are several "colors" of phosphor. The phosphor gets excited by the electrons and in the excitement becomes luminous. If it is a red phosphor it glows red, green glows green, and I will let you guess what blue phosphor glows! Through various ways these three dots of color together can be seen as any one of 256 colors. Each dot has a fancy computer name. These dots are forever more (at least in this document) called Pixels. Stands for Picture Element, if you have to ask. Enough with the techie information, on with the show.

Let me introduce you to a piece of free software (freeware) that works on the Apple Macintosh computer. This free program is called NIH Image. And it does one job brilliantly. Its mission in life is to help humans analyze pixels. One pixel at a time, a group of 9 or an array of 300,000 thousand. It slices, it dices, it can graph, plot, measure, create data sets (which you can export to your favorite spreadsheet for graphing, by the way). NIH Image can magnify the image, edit, enhance, apply a new coat of colors and teach an old dog new tricks.

In fact the guys and gals who invented and maintain the software at the National Institute of Health (NIH) take no less than three pages describing the glorious capabilities of NIH Image.

Beautiful pictures (e.g., GIF, JPEG) versus images with scientific merit for study and analysis (e.g., TIFF, FITS):

Keep in mind that not all images are created (or modified) equally. The images I have used in the four mini lessons (1A, 1B, 1C, 1D) have scientific merit for study. That is, the pixel values represent the brightness of the Viking Orbiter Mars Data.

Brightness or luminosity values (dot for dot) have scientific merit because the pixel values have not been corrupted. Because they are not corrupted, what you see when you open the image is what the Viking "saw."

To corrupt an image is to change the original image pixel values. This corruption or change in pixel value (remember pixel value is nothing more then the brightness of the dot, or luminosity of the pixel) occurs for many reasons. The end result is that individual dots are assigned new brightness values based on values of surrounding dots.

Corrupting the pixel value might happen because a photographer wants to make the image file size smaller. This is done because a smaller image file is easier to use and can be sent quickly to friends and associates. And it looks just as good to the human eye as the original bigger file. Maybe better? So no harm is done if the photographer is interested in sharing the picture's beauty. It is still beautiful. But it no longer can be analyzed for pixel values that have scientific meaning.

One of the first techniques that was used to move images around the Internet was designed to make the picture as small as possible. All files using this technique adds three letters to each image file so people would recognize a picture file from a text file. Those three letters are "GIF" which means Graphical Information Format (I think). This file shrinking technique works great for maintaining the beauty of a picture while making the file as small as possible. But all gif files have corrupted/changed pixel values. Can you guess what the standard file formats for images on the World Wide Web is? Yes, GIFs, and another great file shrinker called JPEG, are the image files of choice. Smaller files transfer from one computer to another more quickly. And this is preferred on the net.

OK, OK! For all the tech heads, if a technique to shrink and unshrink images corrupts the image, it is known as "LOSSY" (information is lost). If it does not corrupt the image when it shrinks, it is "LOSSLESS" (no information is lost).

Note for Windows 3.1 and Windows 95 users: Scion Corporation is making NIH Image work on Wintel Computers. The program is called Image PC. Recently out of alpha testing, it is available at http://www.scioncorp.com.

PC users be aware of the following three facts:

1. This lesson was created and tested on Macs.
2. All new software is buggy and may cause your machine to crash. Tracking and reporting your crashes to Scion will improve the product.
3. Let me know if you successfully used this lesson on a Wintel computer.

SETTING UP THE MAC DESKTOP FOR A QUICK START

When I introduce a new lab to my students, I often use the Mac alias capability for ease of use.

To create Aliases of any file, take the following steps:

1. Click one time on any file to select.
2. Go to the word File in the Command line.
3. Go to the menu Item in File called Make Alias, and let go

In this lesson I created an alias of the image. I drag this alias to the bottom of the desktop. I have kids double click on the alias of the image for the anticipatory set. The Mac automatically launches the application and loads the image to the screen.

Scott Coletti (scolett@quest.arc.nasa.gov)
Creator of this activity
Bringing Image analysis, digital video and the net to the class.
Scott L. Coletti
415-903-6945x237