Digital Focus: An Easier Way to Print

Q&A: Should I Use My Scanner's Image Correction Tools?

My flatbed and film scanners have the ability to change aspects of the image (like color and contrast) prior to the actual scan. Of course, it seems more logical to do this in my photo-editing software where I have more tools at my disposal, and I can see what it's doing a little better. Does the pre-scan editing process provide any advantages or should I just scan everything "raw" and fix them in the separate program?

--Brian Lumadue, State College, Pennsylvania

It's odd, isn't it? Most scanners offer to make tweaks to your picture even though you can see the effect only on a tiny little thumbnail view. It would seem to make sense to wait until you can see how the scan came out in a full-screen view within your favorite image editor.

There's a case to be made for both methods, though, and I'll let you decide which is best. While you have more controls and better insight into what changes actually look like if make them an image editor, many changes will be more precise if done when the image is scanned.

Why, you ask? Because the image is sampled more accurately within the scanning program, with far more bits per color. The more bits you have, the more accurately any given color can be represented. (Consider the fact that an 8-bit image can show any one of 256 colors in each pixel, but a 16-bit image can show any one of 65,536 colors in each pixel.) More bit depth also contributes to better highlights and shadows.

Many scanners sample images with as many as 48 bits per pixel, for extremely high color fidelity. (Make sure that the scanner stores the scanned color depth; many inexpensive scanners scan at a high color depth, like 48-bit, but can only store at a lower level, like 24-bit.) Performing a histogram adjustment with billions and billions of color choices allows the scanning program to do a really bang-up job of tweaking your photo. As soon as the scanner spits the photo into your image editor, though, most of that extra color information is stripped away and you're left with a standard JPEG or TIFF image, which can't hold nearly as much color information. Edits to these images will be inherently less accurate.

Do all those extra bits make much of a difference? Sometimes--it depends upon the image and what you plan to do with it. To see for yourself, try it both ways and decide which way works best for you.