Scanning photos

Here is some more specific information on scanning photos.

Scan Mode:

  • Black and white–use 8-bit grayscale
  • Color–use 24-bit RBG mode (if output to commercial printing, convert to CMYK afterwards)

Determining Scan Resolution: Let your final output device be your guide

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.

Case Study 1: Scanning Pictures from a Printed WorkA 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)