Study Your Scanning Software
Become familiar with the scanning software interface. There may be two menu windows, one for processing your scanned image and one that deals with the scanner hardware preferences (see figure). At the start, set all variables to the manufacturers' recommended defaults. Some scanners may have physical switches for setting hardware preferences, so check your manual carefully before proceeding.
Use an Image Processor
Most scanning software allows you to adjust brightness and contrast levels, make color corrections, crop, scale, and sharpen. These controls are convenient but their preview windows are small. If available, use a scanner plug-in for your favorite image processor (Adobe Photoshop', for example). You will be able to access your scanner from within the processor and use the more advanced adjustment tools to optimize your artwork.
Clean the Scanning Bed
A dirty scanning bed is the leading cause of post-scanning headaches. Check the glass surface of the scanner for dust and fingerprints. Use an anti-static brush or "canned" air to blow away dirt and a soft chemical-free cloth to wipe off smudges. Both products are available from your neighborhood camera store. Water or solvent cleaners are usually not necessary and may not be recommended by the manufacturer.
Calibrate Your Scanner
Before you begin an important project, calibrate your scanner using a test image with a full range of tonal values (note: this step is unnecessary if you only scan black and white line art). Use an original photograph or artwork that has recognizable texture in both the highlight and shadow areas, and a full range of tones in between. Include a gray scale strip chart and color bars, if available.
A professionally photographed studio portrait can be an ideal calibration file. Experiment with color and level adjustments. Take careful notes and output the file to a color proof. Multiple copies of the image can be adjusted and saved as a single document for easy comparison.
Align the Artwork
Place the artwork carefully on the scanner bed. Most scanners have ruled edges and recessed beds to facilitate accurate alignment. The scanner lid should be lowered slowly to prevent the artwork from shifting. Curled photographs or warped art boards may require further assistance. A couple of computer manuals or a copy of the latest congressional budget proposal, placed firmly on the scanner lid, should hold the artwork flat against the glass.
Adjust Levels
Most default settings produce a dark, lifeless scan. Highlight areas are muddy, while the dark tones and shadow areas are dense and lack detail. To compensate, beginners often lighten the entire image, using "Brightness/ Contrast" controls. This helps the dark tones, but you may destroy the highlight areas in the process. Instead, use "Levels" or "Curves" in an image processor (like Photoshop). The "Curves" window offers independent adjustment of the highlights and shadows.
Sharpen
All scanned images can benefit from sharpening. Some software programs sharpen the image during the scanning process, but that may be premature. Rotating, scaling, or resizing after scanning will further soften an image. Make sharpening one of the last adjustments to your image file.
Retouch
Sharpening increases the contrast between adjacent pixels. This can accentuate tiny specks of dust or flaws in the original photograph. Always retouch dust or scratches after using the sharpen filter.
Printing FPOs
Have you had trouble printing fpo scans to a laser printer? Most laser printers bring a whole new meaning to the term "dot gain." Photographs that look good on a computer screen may still print too dark. Try this: Open the "Levels" palette in Photoshop and move the center triangular slider to the left until the data window above reads 1.6 (or you may enter 1.6 directly in that window). The image will look light and washed out on the screen, but will print normally on most laser printers.
Look for more hints and tricks in future columns. In the meantime, remember the ancient computer axiom: "RFM-When all else fails, read the manual."