Xerox DocuColor 40 Reference Manual page 25

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1-11 Optimizing files for processing and printing
The resolution of a raster image, along with its bit depth and physical dimensions,
determine its file size. The following table shows the file sizes of color raster images at
different dimensions and resolutions.
Image size
x
3" 4"
x
5" 7"
8.5" x 11"
x
11" 17"
In this table, the shaded areas indicate that 200 ppi is typically the best trade-off
between image quality and file size. However, higher resolutions (e.g., 250 to 300 ppi)
may be needed for offset printing, when quality is of the utmost importance, or for
images containing sharp diagonal lines.
To find the best image resolution for your purposes, make test prints of some raster
artwork at different resolutions. Start with a high-resolution image (400 ppi) and save
versions at progressively lower resolutions, down to 100 ppi, using a pixel-editing
application such as Photoshop. Always save a copy of the original high-resolution
version in case you need to revert to it. The high-resolution data cannot be recreated
from a lower resolution version.
100 ppi 150 ppi
RGB/CMYK RGB/CMYK
0.4/0.5 MB 0.8/1.0 MB
1.0/1.3 MB 2.3/3.0 MB
2.7/3.6 MB 6.0/8.0 MB
5.4/7.1 MB 12.0/16.1 MB
File size at:
200 ppi
RGB/CMYK
1.4/1.8 MB 5.5/7.3 MB
4.0/5.3 MB 16.0/21.4 MB
10.7/14.3 MB 42.8/57.1 MB
21.4/28.5 MB 85.6/114.1 MB
400 ppi
RGB/CMYK