Line Screen Frequency Settings in CorelDRAW

Line screen frequency, measured in lines per inch (LPI), dictates how fine or coarse halftone dots appear when printing color separations in CorelDRAW. Selecting the proper LPI setting depends entirely on the target output method, the printing substrate, and the capabilities of the output device. This guide explains how line screen frequency functions within CorelDRAW, outlines standard LPI values for various print processes, and details how to configure these settings directly in the print separations menu.

Understanding LPI in Color Separations

Line screen frequency controls halftone dot distribution. A higher LPI produces smaller, tightly packed dots for finer detail, while a lower LPI produces larger, more visible dots. Setting the frequency too high for your printing method can cause dot gain and ink bleeding, leading to muddy prints. Setting it too low results in visible dot patterns and a loss of image clarity.

Standard Line Screen Settings by Process

Different printing methods require specific frequency ranges based on ink viscosity, substrate absorbency, and transfer mechanisms:

  • Screen Printing (Textiles): 45 to 65 LPI. The general rule is to divide your screen mesh count by 4.5 or 5 to determine the maximum usable LPI (for example, a 230 mesh screen supports approximately 45–50 LPI).
  • Screen Printing (Flat Stock/Signs): 65 to 85 LPI, typically paired with 305 to 355 mesh counts on smooth surfaces.
  • Offset Lithography (Coated Paper): 150 to 175 LPI for high-detail commercial printing.
  • Offset Lithography (Uncoated Paper): 120 to 133 LPI to compensate for dot absorption.
  • Newspaper Printing: 85 to 100 LPI due to high ink absorption on porous newsprint.
  • Flexography: 85 to 133 LPI depending on the plate material and substrate.

Standard Screen Angles for CMYK Separations

When setting screen frequency, complementary screen angles must be assigned to avoid moiré interference patterns:

  • Black: 45° (the most visible color placed at the least noticeable angle)
  • Magenta: 75°
  • Cyan: 15° or 105°
  • Yellow: 0° or 90° (the least visible color placed at the most noticeable angle)

For spot color separations, angles are typically set to 45° if only one or two colors overlap, or adjusted by 30° increments between touching plates.

How to Set Line Screen Frequency in CorelDRAW

Line screen settings require a PostScript-compatible printer driver, a PostScript RIP (Raster Image Processor), or outputting to a Device Independent PostScript file (.prn or .ps).

  1. Open your document in CorelDRAW and click File > Print.
  2. Select a PostScript printer or choose a PDF/PostScript driver.
  3. Go to the Color tab and select the Separations option under Output Color.
  4. Switch to the Separations tab in the Print dialog box.
  5. Check the Use advanced settings checkbox if available for your driver.
  6. Locate the separation plates listed in the window. You can adjust the global Screen (LPI) field, or double-click individual plates (Cyan, Magenta, Yellow, Black, or Spot colors) to manually override the frequency and angle for each ink plate.
  7. Verify that your RIP device is not set to override application screen settings if you want CorelDRAW to dictate the final output values.
  8. Click Print or Print Preview to review the separated plates and halftone simulations.