The scanner? You might be thinking that I have confused the scanner with a photo-editing program. Well, there is a bit of a gray area there, admittedly.

First, let's define some terms. Scanners are controlled by programs called "Scanner Drivers." The Scanner installation program is the one that copies those programs to your computer. Just like there are many different kinds of scanners, there are many different kinds of scanner drivers.

In general, we would rather perform a function (such as descreening) in the scanning stage than afterward.

Size Matters
A digital photo's size is measured in dots, called "pixels" for "picture elements." If you scan a 4x6 photo at 200 dots per inch (DPI), the resulting image will be 800 pixels high and 1200 pixels across. If you want to make the picture larger, you can scan it at 300 DPI. Most scanners sold today can scan at 1600 DPI or more.

Here's one thing that confuses people—there is no difference in increasing the resolution and enlarging the image on the scanner. If you increase the resolution from 200 to 400 DPI, it has the same effect as enlarging the image 200%. Even though there are two different controls that you can adjust, they have a single effect.

There is no better time to enlarge your photo than in the scanning process. Once you've scanned an image, you've got all the dots you're going to get. After that, if you want to enlarge the image, you have to "make up" the dots that will go between the ones you've scanned—a process called "interpolation." But if you want to scan at a "higher resolution" you can do that—and the dots actually come from the image.

It's not just enlarging the entire image. I have a picture of my uncle when he was in the army. There must be 200 guys in the picture. My uncle's face takes up about 1/8 of a square inch on the page. If I wanted to make a 4x6 image of that, I'd have to scan it at the maximum optical resolution of my scanner.

Descreening
In the recent article about scanning newspapers, we talked about "descreening." When materials are printed in newspapers, magazines, and other media printed on presses, the artwork is "screened" and printed on the media at an angle. This creates an interference process, which needs to be "descreened" to make the image look right. If your scanner driver includes a descreening setting, you will want to use that one, instead of one in a graphics program that you use later in the process of enhancing the photo.

Histogram
A histogram is a name for a graph that shows how many pixels in the image have a given lightness or darkness. You can use the histograms to adjust the brightness before creating the scanned image. This same function is available in your photo manipulation program, but it's good to do it earlier if you can. If your scanner driver has brightness settings, you might want to adjust those before you save the scanned image.

A histogram has a graph that looks more or less like a mountain, with a high middle and low ends. They don't all look like that, but work with me here, it's complicated. Below the graph are two triangles, one at each end. One is for black, and one is for white, but ignore that and just try to get the ends close to the data. If there's any air between the triangles and the mountain, you need to slide the triangles inward, until the triangle is under the edge of the mountain. If your mountain looks like several mountains, only move the triangles in until you get to the first one.

If you scan them in color, you'll have a red, blue, and green histogram to fix. For three fun times, you get to bracket the mountain.

But wait, there's more. Between the two triangles on the ends is a triangle in the middle. That's the midpoint, the gray value. If you slide it left or right, you change the brightness of the image. It's a great way to make a picture stop looking milky, and really pop. An example can be found here.

Unsharp Mask
The Unsharp Mask is a confusing name for a function that tries to sharpen photos that lack focus. What it does is increase the contrast wherever light and dark areas are close together. If you have an unsharp mask setting on your scanner, you might want to use that to sharpen the image while you scan it.

Digital Ice
Applied Science Fiction makes a computer program named Digital ICE. This program can repair cracks and scratches during the scan. There is only one flatbed scanner that contains this firmware—the Microtek 6800. It's priced between $340 and $400. You can find examples at this site. If you've ever spent hours trying to clean up a scratched image, you will want to check this out.

Summary
You can use a scanner to enhance an image in more ways than you might have imagined. Try them all, and have fun. Next time we'll talk about the basic use of photo editing programs like Photoshop Elements.

More Information
For links and more information about basic photography, please see the RootsWorks site at: www.rootsworks.com/basicphoto. If you want to discuss your photography challenges, please drop by the RootsWorks Forums. Registration is free, and I'd be interested to know what kinds of issues you are facing.