- IMAGE PREPARATION
- IMAGE RESOLUTION
- HALFTONE
REPRODUCTION
- BLACK & WHITE
HALFTONE REPRODUCTION
- MECHANICAL
SPOT COLOR
IMAGE
PREPARATION
In order to achieve optimum newspaper reproduction, certain guidelines
and specifications need to be considered when preparing your digital
files. The following information will help you optimize your files
for reproduction in the Mercury News.
IMAGE
RESOLUTION
Factors for input and output resolutions must be taken into consideration
to ensure best quality reproduction. For best results, scans should
be made at final size and crop. Although reducing or cropping an
image after scanning does not adversely effect the image quality,
enlarging the image reduces overall resolution and quality. Planning
ahead and scanning for the largest anticipated output size minimizes
the need to rescan an original for satisfactory resolution.
Continuous Tone
Images:
For good quality scans, the general rule is to scan images at a
resolution of 2 times the output line screen ruling. Since the Mercury
News prints at 100 lpi, the equation would be 2 x 100 = 200 dpi.
Scanning at a higher resolution than needed does not necessarily
improve the quality of an image and could adversely effect processing
time and storage space requirements.
NOTE: It is
not a good idea to scan an image which has already been converted
into a halftone (i.e.printed media). This will most likely lead
to a moiré in the printed image.
Line Art:
Scanning line art requires considerably more input resolution than
continuous tone images. Ideally, elements should be scanned in at
the same resolution they will be output. For newsprint, 1200 dpi
is the recommended output resolution for quality reproduction. This
minimizes jagged or stair-stepped edges and results in smooth, sharp
images.
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HALFTONE
REPRODUCTION
A halftone is a continuous tone image that has been converted into
various size dots for print reproduction. An important aspect which
must be compensated for in press reproduction is dot gain. Because
of the highly porous characteristic of newsprint, newspaper reproduction
incurs a significant amount of dot gain. With an 85 line screen,
halftone dots gain 12-15% in size for highlights and shadows, and
28-34% in the midtones. For example, a 50% dot grows to approximately
an 80% dot on the press. Dot gain adjustments must be made to avoid
muddy reproduction and dirty colors. Below you will find guidelines
to help you compensate for dot gain in your halftones.
BLACK
& WHITE HALFTONE REPRODUCTION
Newspapers
usually cannot print less than a 5% dot and "plug up" at about 85%.
Dot gain averages 30-34% in the midtone, meaning that a 50% dot
will grow to as much as an 84% dot on press. Typical dot gain values
are:
| Dot
Size (%) |
05 |
10 |
15 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
90 |
| Dot
Gain (%) |
13 |
16 |
21 |
25 |
32 |
34 |
34 |
25 |
22 |
16 |
10 |
Resulting
Dot (%) |
18 |
26 |
36 |
45 |
62 |
74 |
84 |
85 |
92 |
96 |
100 |
Our available
range of tones is about 80 percentage points. The secret behind
good tonal reproduction is distributing the original image's grays
over these remaining tones. This is done through the application
of transfer functions to your scanned images.
MECHANICAL
SPOT COLOR
The Mercury News has printed a NAA Ad-Litho color chart to insure
predictable printed results when using spot colors in your ad. All
of our spot colors are created with process color inks. Please contact
your sales representative to get our most current chart of spot
color mixes.
When producing
spot color mechanically with process color inks, it is important
to take dot gain and secondary color contamination into consideration.
This follows the same logic applicable to the subtle color corrections
needed in separating continuous tone originals.
To reproduce
a lighter shade of the spot color, reduce the specified screens
by the desired tint shade value.
Example: A 50%
tint of NAA Ad-Litho 0740 Red
Specified screen
breakdowns for 100% 0740 Red are 70% magenta, 40% yellow.
Breakdowns for
50% tint shade are 35% magenta, 20% yellow.
Please set up
your files to output spot colors as process (CMYK) colors.
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