UMAX Technologies Astra 2000U Owner's Manual page 50

You can scale the image using any of the scale factors listed below:
200%
150%
100%
50%
25%
10%
Custom
You can also specify a custom scale factor by choosing the Custom
option from the Scaling drop down menu. See the Using Custom
Scaling Settings section that follows for more information about
specifying a custom scale factor.
Using Custom Scale Settings
You can specify custom scaling settings that you can use when you
scan. To define the custom scaling settings:
1.
Choose the Custom... option from the Scaling drop down
menu. The Custom Scaling window opens.
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