CHAPTER 6 GETTING YOUR PIX ONSCREEN 77- This example “scales” properly: a 1×1.5-inch print easily scales to 10× 15
inches. But what if the output doesn’t match the aspect ratio of the negative
or print? You will need to crop either the input or the output. For example, if
the image to be scanned is 3×3, you could crop the dimensions of the scan to
2 ×3. This will crop some of the image, but later it will print properly.
Table 6.2 shows some typical requirements for scanner samples per inch.Table 6.2 Typical Requirements for Scanner Samples Per Inch
Final Output Scanner Sample
Final Output Pixels Per Inch Rate Required
An image in a print 8 magnifications × 250 pixels per inch 2,000 samples per inch
An image on a monitor 4 magnifications × 95 pixels per inch 384 samples per inch
A poster size image 48 magnifications × 50 pixels per inch 1280 samples per inch
Offset (magazine) 8 magnifications × 300 pixels per inch 2400 samples per inch
printing at 120 screen
lines per inch- If the image scales naturally or after cropping, determine what the output
requires in ppi (pixels per inch). A photo printer can handle from 150–300
ppi. Most Web sites assume images are 72 ppi or 96 ppi. Assuming your goal
is a print from a photo printer, 200 ppi is adequate. - Finally, multiply the magnification factor by the number of pixels per inch.
For example, a magnification of 10 for a print with 200 pixels per inch
requires a scan of 2,000 samples per inch. Set the scanner to 2000 samples
per inch. Most scanners use the term dpi(dots per inch) instead of samples
per inch. If your scanner does not allow custom settings such as 2000, set the
scanner to the highest number around this amount, such as 2400 dpi.
The following sections explain further preparation for scanning for a specific type of
output.Scanning for Internet Output
If the image is for the Internet (or any multimedia presentation), it must look as
sharp as possible. Computer monitors only display between 70 and 100 pixels per
inch, so even a small amount of unintentional blurring is easily noticed and results
in an unprofessional-looking image.