UMAX Technologies Astra 2000U Owner's Manual page 44

The table below gives you an idea of the file sizes you can expect
based on the original image size and the resolution setting you
specify. These values are based on scanning images in 24-bit, True
Color RGB mode. Image sizes shown below are given in
MegaBytes.
Table 1. Resolution/File-Size Guidelines
Resolution
(dots per inch)
72
100
200
300
400
600
800
1200
NOTE: Choosing the True Color RGB 36-bit setting captures more
data than the 24-bit setting. This means that the file sizes listed
above will be larger if you scanned images using the True Color 36-
bit RGB setting.
Choosing the Best Resolution for Your Scanning Project
To choose the best resolution for scanning, determine what you are
going to do with the image once it is scanned. Matching your
scanning resolution to the image use will give you the best image
for that purpose and will keep the file sizes to the minimum needed.
Table 2. Recommended Resolutions
Image Use
Printing
Viewing on the Screen
Viewing on the Web
OCR, B/W
Pre-Press
Enlarging or reducing
* Depending on the resolution of your printer
44
Image Size: Image Size:
4x5 5x7
0.30 0.53
0.58 1.00
2.29 4.01
5.15 9.01
9.16 16.00
20.60 36.10
36.60 64.10
82.40 144.20
Image Size:
8.5x11
1.39
2.68
10.70
24.10
42.80
96.30
171.20
385.20
Recommended Resolution
300 – 600*
72
72
300
600
600