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Working with Color
Optimizing files for processing and printing
Resolution of
raster images
62
The following sections provide tips on how to create image files that
produce the highest possible print quality while minimizing the processing
time and disk space they require.
While a 72 ppi raster image appears sharp on a monitor, the same image
would likely appear pixelated when printed to the KX-P8420. Color print
devices are capable of much greater detail than monitors, and require
correspondingly higher resolution image files. However, high-resolution files
can be large, and therefore cumbersome to transmit over a network,
process for printing, store on disk, and edit.
Beyond a certain threshold, a higher image resolution greatly increases file
size while having a minimal effect on output quality. The optimal image
resolution depends on the resolution of the final print device. Aim for the
resolution that optimizes both file size and output quality.
The resolution of a raster, 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
100 ppi
size
RGB/CMYK
3" x 4"
0.4/0.5 MB
5" x 7"
1.0/1.3 MB
8.5" x 11" 2.7/3.6 MB
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.
File size at
150 ppi
200 ppi
RGB/CMYK
RGB/CMYK
0.8/1.0 MB
1.4/1.8 MB
2.3/3.0 MB
4.0/5.3 MB
6.0/8.0 MB
10.7/14.3 MB
400 ppi
RGB/CMYK
5.5/7.3 MB
16.0/21.4 MB
42.8/57.1 MB
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