Scanning Basics
by Ginger Rosenkrans
Scanning Resolution
The resolution for a scanned image is determined by the
capability of the output device. Inkjet printers can produce a 75 line screen
for halftones, so you can scan your images at 150 dpi. For high-end output
devices, if you want a 133 line screen in the final printed piece, then scan at
300 dpi. For black and white or color photos, you should choose the resolution
based upon two factors: what you plan on doing with the photo and if you plan on
enlarging the photo. If you are printing the image, you should scan at 150-200 ppi. If you plan to enlarge an image after it is scanned, then scan at a higher
resolution to provide enough detail. If you are scanning for a Web page, you
should scan around 72-75 dpi.
Scanning for
print: scan about 300 ppi/dpi
Scanning for
Web: scan around 72-75 dpi
How to scan in
Photoshop:
position image in scanner, face down
be sure glass on scanner is clean
close all application programs so you can reserve enough
RAM for Photoshop
start scanning process: File>Acquire/Twain>
it automatically does a prescan
for Type, choose “color photo” “B&W” or B&W
drawing
select path—select dpi
crop if necessary
press Final to scan image
opens directly in Photoshop
NOTE: best to scan for IBM PC instead of for MAC
unless you know for sure the final print job will done on a MAC. MAC can read an
IBM PC file but IBM PC file cannot read a MAC’s.
Adjustments
in Photoshop
1. Change mode (mode menu)
2. RGB for color photos and on monitor (RGB uses less
memory than CMYK. You can convert to CMYK before printing)
3. Bitmap for line drawings
4. Grayscale for B&W photos
5. If you want to adjust/resize image
--use
Edit>Transform>Scale (remember, to execute the transform you need to click
on move tool and then the transform will ask you to apply)
--use crop tool
--use image menu “image size” but make sure constrained
box is checked
6. If you want to adjust color, brightness/contrast, to
make clear if blurry, and more, then use Image>Adjust and select the mode
(e.g., hue and saturation)
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