Image Processing Reference

In-Depth Information

Example

Figure 2.37

Scaling factor = desired size/original size

For
screen output
, you should initially aim for a target resolution of 100

dpi (rounded up from 96 dpi):

1.

In the example, the worker in the miniature slide measures 0.8 inches

in the original image. Let's say that you want him to be 8 inches in the

screen output. This means you have a scaling factor of 10, so you would

select 2 as your scanning factor.

2.

The house measures 10 inches in the original, and you want it to be 8

inches in the new image. So you reduce it, obtaining a scaling factor of

0.8. Again, you can choose a scanning factor of 2.

Calculation by the formula
:

• Resolution (desired) for 1 is 100 dpi; for 2 it's 100 dpi

• Scaling factor for 1 is 8 in: 0.8 in = 10; for 2 it's 10 in: 8 in = 0.8

• Scanning factor (selected) for 1 is 2; for 2 it's 2

• Scanning resolution for 1 is 100 dpi × 10 × 2 = 2000 dpi

• Scanning resolution for 2 is 100 dpi × 0.8 × 2 = 160 dpi

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