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It is not a coincidence that the overwhelming majority of text you see is printed in black on 
white paper. Text in black on white is highly legible and is not fatiguing to read for extended 
periods. For many color materials, using black text on a white background and confining 
color to graphic elements and headings is a good choice.

When used skillfully, color text can add flair to documents printed on paper. This technique is 
widely used in presentations. When using color text, avoid dazzling text and background 
combinations created from primary complements, especially red and cyan or red and blue. 
They are visually fatiguing and hard to read. Color text is more legible when distinguished 
from its background by a difference in lightness, for example, dark blue text on a light beige 
background. In addition, using many different colors in a string of text makes for a confused 
appearance and is hard to read. However, using a single highlight color is an effective way to 
draw the reader’s eye to selected words. For color text samples, see the following figure.

When using color text, keep in mind that small font sizes typically do not print in color with 
the same sharpness as in black. In most applications, black text prints exclusively in black 
toner, while color text usually prints with two or more toners. Any misregistration between 
the different toners on paper causes color text to lose definition. You can make test prints to 
find the smallest point size at which color text prints clearly. When using high-end graphics 
applications that allow you to specify color as percentages of cyan, magenta, yellow, black, you 
can create pure cyan or pure magenta text that prints with the same sharpness as black text. 
(Pure yellow text is extremely hard to read on anything but a dark or complementary 
background.)

Exceptio 

probat

regulam de rebus
non exceptis.

De 

gustibus

 

non 

est

 

disputandum

.

Two broad categories of artwork can be printed from a personal computer to a color printer:

 and 

.

A raster image, also referred to as a bitmap, is composed of a grid of 

, each assigned a 

particular color value (as illustrated in example a in the following figure). The grid, when 
sufficiently enlarged, resembles a mosaic made from square tiles. Examples of raster images 
include scans and images created in painting or pixel-editing applications, such as Photoshop 
and Corel Painter.

. The 

resolution of a raster describes the compactness of the pixels and is specified in pixels per inch 
(ppi). The bit depth is the number of bits of information assigned to each pixel. Black and 
white raster images require only one bit of information per pixel. Grayscale images require 8 
bits per pixel. For photographic quality color, 24 bits of RGB color information are required 
per pixel, yielding 256 levels of red, green, and blue. For CMYK images, 32 bits per pixel are 
required.

When printing raster artwork, the quality of the output depends on the resolution of the 
source raster. If the raster resolution is too low, individual pixels become visible in the printed 
output as small squares. This effect is sometimes called “pixelation.”

In 

, picture objects are defined mathematically as lines or curves between 

points—hence the term “vector” (see example b). Picture elements can have solid, 

or patterned color fills. Vector artwork is created in illustration and drawing applications, such 
as Illustrator and CorelDRAW. Page layout applications, such as QuarkXPress, also allow you 
to create simple vector artwork with their drawing tools. PostScript fonts are vector-based, 
as well.

Vector artwork is resolution-independent. You can scale it to any size and resolution without 
danger of pixels becoming visible in printed output.

The following sections provide information about 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 Color Server. Color printers are capable of much greater detail 
than computer 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 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.

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 (for example, 250 to 300 ppi) may be 
necessary 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 must revert 
to it. The high-resolution data cannot be recreated from a lower resolution version. 

3"

x

4"

0.4/0.5 MB

0.8/1.0 MB

1.4/1.8 MB

5.5/7.3 MB

12.4/16.5 MB

5"

x

7"

1.0/1.3 MB

2.3/3.0 MB

4.0/5.3 MB

16.0/21.4 MB

36.1/48.1 MB

8.5"

x

11"

2.7/3.6 MB

6.0/8.0 MB

10.7/14.3 MB

42.8/57.1 MB

96.4/128.5 
MB

11"

x

17"

5.4/7.1 MB

12.0/16.1 MB

21.4/28.5 MB

85.6/114.1 
MB

192.7/256.9 
MB

Print the files and examine the output. You will likely begin to see a marked deterioration in 
output quality at resolutions below 200 ppi, while above 200 ppi the improvement may be 
very subtle. 

Raster images prepared for offset printing may need to be at higher resolutions than necessary 
for proofing on your Color Server.

Ideally, each raster image should be saved at the actual size, and it will be placed in the 
document at the optimal resolution for the printer. If the image resolution is correct for the 
printer, there is no quality advantage to be gained by scaling an image to a percentage of its 
actual size. If you scale a large image to a percentage of its actual size, you incur unnecessary 
file transfer time, because the image data for the entire large image is sent to the printer. If an 
image is placed multiple times at markedly different sizes in a document, save a separate 
version of the image at the correct size for each placement.

If you must place an image at greater than 100% in a document, remember that the output 
image resolution is affected. For example, if you scale a 200 ppi image to 200%, the image is 
printed at 100 ppi.