Optical scanners are wonderful for those of us with the urge to collect and identify plants and animals, but maybe we don't have the space to keep such collections, or else just don't like the idea of killing things.

For example, I don't even want to kill insects, but I'd like to document the fact that I've encountered some of the rarer and more spectacular species in my area. I've solved the problem by collecting scanned images of them, one of which appears at the right. More such images appear on my Insect Profiles page. Therefore, how do such images come about?

CHOOSING A SCANNER

When you shop for a scanner you will run across cryptic product specifications such as those below, for the popular Canon CanoScan 4400F Color Image Scanner. After each point the text in blue explains what they mean.

• High resolution, high speed scanning with USB 2.0 Hi speed interface

  {"High resolution" means lots of detail, but it doesn't say how much. "USB" is the kind of connection that connects the scanner with the computer. Nowadays nearly all connections are via USB. The USB 2.0, introduced in 2001, has a speed of 480 Mbits/second, which is awfully fast, but USB 3.0, introduced in 2008, is faster, with 5 Gbit/second. You can find more than you want to know about USB on the Wikipedia USB Page.}

• Built-in film adapter for scanning 35mm and slides

  {This enables you to scan images from 35mm film and slides as if they were paper. As when scanning from paper, you end up with an image in digital form you can download into your computer}

• 7 easy buttons to quickly copy, scan, e-mail or create multi-page PDF files

  {Sometimes you must install software onto your computer and operate the scanner from your computer by clicking on icons. This indicates that you can operate the scanner from the scanner itself without having to fool with the computer.}

• Spectacular scans: Produce scans with spectacular resolution of up to 4800 x 9600 color dpi.

  {"DPI" means "dots per inch." Pictures in books and on our computer screens are composed of dots, so this number is a guide to how sharp we can make our pictures. The sharper the images are, the more we can enlarge them without the images getting blurry. For making images to be shown on computer screens, 600 x 1200 or even 600 x 600 is  sharp enough for most people, so clearly 4800 x 9600 is way more resolution than we need. If we may want to enlarge our images greatly and print them on glossy paper, then the 4800 x 9600 dpi may be useful. It's interesting to note that an inkjet printer sprays ink through tiny nozzles at about 300-600 dpi. A laser printer applies toner through a controlled electrostatic charge in the range of 600-1800 dpi. A more detailed and technical survey of the dpi situation can be seen on Wikipedia's DPI Page.

• Rich, vivid color: 48-bit color depth yields over 281 trillion possible colors.

  {"Color depth" describes the number of bits (the smallest unit of data in a computer) used to represent the color of a single pixel (the smallest dot making up a picture on a computer screen. Many scanners using 36-bit color provide excellent results, so 48-bit color is more than enough.)

SCANNING

To be honest, scanning insects, leaves and the like is really no big deal. It's the easiest part of the whole operation. You find a wasp, you lie it on the scanner's glass, on its back (remember the scanner's "eye" is below, so if the wasp lies on its back the image will show it from "above") and you hit the scan button.

Of course there are a few things to keep in mind.

Mainly, keep in mind that there's no point in using the highest scanner settings for every scanning. Your urge is to choose the highest settings, but if you do that you're going to end up with an image file several millions of bytes large -- several MBs. A few huge image files like that will fill up your hard disk fast and if you try to send them via email they may take some time to download. If you're on a modem, it can take hours! Right now you should digest this fact:

The wasp picture at the top of this page is from a file 7,430 bytes large. That's 7.43 KB, or 0.007MB.

Therefore, if you scan something like that and the file holding the image ends up being 1.5 MB large, which very easily could happen, you have made the file over 200 times larger than it needs to be. That means that you are filling your hard disk with files 200 times faster than you need to, and if you put the image on the internet it will download only 1/200ths as fast as it could.

When I scanned the wasp I chose the 300 dpi setting and even still had to reduce the picture with a graphics program, as described on our Graphics Programs Page. Of course, sometimes you do want to enlarge things, and then you can crank up your program to 1,200 dpi or beyond. It's always neat to create "insets" with much-enlarged images like the one at the right. For the enlarged Juncus flower in the orange box I used 600 dpi. To make the boxes I used a graphics program.

With the above basic information you should be able to make some scannings that will surprise you with their high quality -- like the wasp head at the left. After you've collected scannings for a while, I think you'll find looking at them much more enjoyable (and less messy) than making regular insect collections or creating an herbarium of dried plants. Also you'll be able to send them to friends via email, and make neat Web sites like this one... and you won't be killing things!

IMAGE SCANNERS: