Scan Mode:
|
If your final output process is printing to |
Its linescreen (lpi) is |
Scan at this resolution (2 x lpi) |
|
Laser printer |
85 |
170 |
|
Newspaper |
85 to 120 |
170 to 240 |
|
Quick Print shop, Copy shop |
100 to 120 |
200 to 240 |
|
Newsprint magazines |
100 or 120 |
200 or 240 |
|
Glossy magazines |
150 |
300 |
|
Coffee table books |
175 |
350 |
|
Museum quality art books |
200 |
400 |
|
Output to Web/monitor screen |
Screen Resolution is 72 ppi or 96 ppi |
72 or 96 ppi |
|
Inkjet Printer |
Look up default resolution in manual |
Scan at no more than one-third of set resolution to prevent over-saturation |
Part of the table adapted
from: Cohen,
Sandee, and Robin Williams. Non-Designer's Scan and Print Book.
Berkeley: Peachpit Press, 1999. p.91.
A scan made from a printed work (magazines, books) is likely to exhibit blotches or dot patterns known as moirZ, which is due to the use of halftone screens used in the printing process. To minimize moirZ, scan at 2x the desired resolution with the ÒdescreenÓ option selected. The resulting scan can then be resampled to half the image size in Photoshop before saving the file.
Case Study 2: Optimize viewing quality of a page with color imagesIt is possible to adjust the exposure of the scanned image to obtain a clean white background for text legibility while retaining the color balance of graphics on the same page.
Within PhotoShop, go to Image ^ Adjust ^ Auto levels ( to set the white and black point automatically). Then select Auto Contrast under the same menu. To further adjust the exposure, use Brightness and Contrast option under the same menu.
When you are happy with the change, File ^ Save or Save as (another file format)