Choice
of screen rulings for different papers and types of press
Paper type
Litho presses
Bookwoves
120 lpi
Opaque/Offset Papers
120 – 133 lpi
Coated Cartridges
120 – 150 lpi
Art Papers
120 – 175 lpi
Reproduction
examples of line screen/half-tones/tint values
Line screen and half-tone image
60 lpi
100 lpi
120 lpi
150 lpi
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
Supplying halftones for our digital web press
Our Nipson digital web press prints using a technique called magnetography which fuses toner to the paper. The toner is very dense and black and so the dot gain appears
much higher than that of a conventional litho press.
Therefore our digital web press requires a unique
halftone screen pattern to accuratly render shades of grey.
This halftone screen pattern needs to be one of a low lpi, but also contains a white-out screen within
the screen to further reduce the dense appearance of the toner:
However this is only in the case of photographic images which contain a large number of grey-levels.
With simple graphic images, such as grey text, pie-charts, and logos, the number of grey-levels are
far fewer, and so a tighter line-screen can be used.
To take advantage of this, the RIP automatically evaluates and segments the imposed pages sent to
press, and uses a different, tighter line-screen for segments of graphics to those of photographics:
Guidelines to supplying files for use on our digital web:
Most pictures and graphics need no special handling by the supplier. Use vector graphics for best
reproduction. To get the quality of raster graphics as good as possible, please follow these tips:
Ensure any line-art images are 600dpi, 1-bit (black & white) and not grey-scale
If graphics include any text, try to not anti-alias the text. Use threshold in Photoshop to make textblack and white (you may wish to increase the resolution to 600dpi).
Try to ensure logos etc that are supposed to be solid grey only actually contain 1 grey-level.
(Posterise in Photoshop). If the RIP detects many grey-levels it will screen as a photograph (75lpi).
Do not compress graphic images, as this will increase the number of grey-levels.
If graphics include any text, try to not anti-alias the text. Use threshold in Photoshop to make text
