Sandy-P FAQ

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What are the advantages of Sandy-P compared with other screen dot shapes ?

Due to its unique shape Sandy-P has a late dot closure (at around 95% to 98%). By this the visible differenciation of gray levels increases in the dark areas. The dot remains open until the end and ensures the visibility of dark shades of gray.
Due to the dot geometry the screen frequency can be increased without changing the resolution. A stable production print can easily be achived with screen frequency of  56 l/cm (142 lpi) at 1270 dpi on standard newspaper paper.
Due to the smooth dot gain and not having a double dot closure (as it happens with eliptical dots) continuous shades along the whole tonal range without tonal jumps are achived
Compared to FM screening Sandy-P has the advantage that the dot gain is less. This is because the free perimeter length of Sandy-P is far less than that of FM. Due to this it is more easy to stabilize the dot gain - especially in web offset printing.

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Does Sandy-P have a bigger dot gain compared with other screen dot shapes ?

No, the dot gain of Sandy-P is comparable with an eliptical dot shape. Compared to FM screening it is even much less and more predictable. Due to this a rip calibration based on test prints can easily be done.

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Does the specific dot shape increase the risk for moiré ?

No, usually moiré is independent from the dot shape. Moiré usually occurs through the combination of specific structures in the subject and the screening. In this case it works best to move all screen angles by 7.5 degrees.

Example:
Cyan = 15° => 22,5 °
Magenta = 75° => 82,5°
Yellow = 0° => 7,5°

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Which screen angles are used with Sandy-P ?

Sandy-P can be used with all common screen angles. We recommend, however, especially when subjects are used with skin tones, switching the angle between magenta and black.

Example:
Magenta = 75° change to 45°
Black = 45° change to 75°

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Can I use HPS (Halequin precision screening) with Sandy-P ?

Yes, HPS is recommended for accurate screen angles and frequencies.

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Which RIP can be used with Sandy-P ?

Sandy-P is developed for Haelquin based RIPs. Currently Harlequin is the only RIP manufacturer that provides an open interface for screening.

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Which screen frequencies can be used with Sandy-P

Any screen frequency can be used (limited by the resolution of plate- or imagesetter)
We recommend the following settings:

  • with 1200 – 1270 dpi newspaper printing
    • on "normal" paper:
      starting with 48 L/cm = 122 lpi to max. 56 L/cm = 142 lpi
    • on higher-quality papers:
      to max 60 L/cm = 152 lpi
  • from 2400 – >2540 dpi commercial printing
    • on web offset:
      beginning with 80 L/cm = 200 lpi to max. 100 L/cm = 254 lpi
    • on sheet-fed offset:
      to max 150 L/cm = 380 lpi