SUMMARY
Scanned images can drastically increase the amount of time and disk space
it takes to save a file, as well as the amount of time it takes to print.
The amount of detail recorded by the scanner is measured in dots-per-inch
(dpi). The higher the resolution or dpi, the more detail in the image and
the larger the file size. When you add a scanned image to a
file, you may want to keep the following points in mind:
- Use the optimum scanning resolution to keep images from getting unnecessarily large. Do this by matching the scanning resolution to the capacity of the output device.
- If an image has more resolution than a printer can print, the printer simply ignores the excess.
- The best scanning resolution is equal to two times the number of lines per inch (lpi) of the printer.
The following table will help you select the optimum scanning resolution.
|
Output device |
Output dpi |
Output lpi |
Scanning dpi |
|
Monitor |
96 |
NA |
96 |
|
Laser printer |
300 |
55-65 |
120 |
|
Laser printer |
600 |
65-85 |
150 |
|
Ink-jet printer |
300 |
50-60 |
110 |
|
Dye sub printer |
300 |
55-70 |
125 |
|
Imagesetter |
1250+ |
120-150 |
300 |
You may also want to consider the following "rules of thumb."
Scan at an Appropriate Resolution
If you are scanning in color or grayscale, scan at no more than one-half the resolution of your printer. Therefore, if your laser printer prints at 600 dpi, scan at no more than 300 dpi. If you are scanning in black and white, scan at no more than your printer resolution, but make sure that your scanner is set to "black and white" or "line art."
Scan at an Appropriate Color Depth
If your original artwork is in color, but you will only be printing to a black and white printer, scan it in grayscale. If your original artwork is a black and white line diagram, scan it in black and white.
Scan at an Appropriate Size
Use your scanning program to scale the original artwork. For example, if you are scanning a 5-by-5-inch logo to place on a business card, use the scaling controls in your scanner software to reduce it to around 20-percent (1-by-1-inch). Then use the scaling commands in Publisher to get the logo exactly the right size.