How to Set Screen Angles in GIMP Newsprint

This guide explains how to configure the screen angle for individual color channels using the Newsprint filter in GIMP. Adjusting distinct screen angles for separate channels is essential for replicating authentic commercial halftone printing and avoiding visual interference known as the moiré effect. Following the steps below, you will learn how to access the filter, switch color models, and assign precise angles to each channel.

1. Open the Newsprint Filter

Open your image in GIMP, then navigate to the top menu and select Filters > Distorts > Newsprint. This opens the GEGL-based Newsprint dialog window with real-time preview capabilities.

2. Choose Your Color Model

In the Newsprint dialog settings, locate the Color model dropdown menu. Choose the model that matches your desired output:

  • RGB: Best for digital art or standard screen displays (Red, Green, Blue).
  • CMYK: Best for simulating physical four-color process printing (Cyan, Magenta, Yellow, Key/Black).

Selecting a multi-channel model activates independent control tabs or selectors for each respective channel within the dialog.

3. Select and Configure Channel Angles

Once your color model is chosen, the filter organizes channel properties under separate tabs or a channel selection menu (such as Channel 1, Channel 2, Channel 3, and Channel 4):

  1. Click on the first channel (e.g., Cyan or Channel 1).
  2. Locate the Angle slider control.
  3. Input or drag the slider to your desired degrees.
  4. Switch to the next channel tab and enter a different degree value. Repeat this process for all available channels.

4. Standard Halftone Angles for CMYK

To minimize moiré patterns when using the CMYK model, industry-standard offset printing angles are typically configured as follows:

  • Cyan (Channel 1): 15°
  • Magenta (Channel 2): 75°
  • Yellow (Channel 3): 0° (or 90°)
  • Black / Key (Channel 4): 45°

If working in RGB mode, space the three angles roughly 30° apart (such as 15° for Red, 45° for Green, and 75° for Blue) to maintain a balanced visual distribution.

5. Finalize the Output

Fine-tune other channel-specific parameters if needed, such as Period (dot size) or Pattern (line, circle, diamond), to complement your angle configurations. Click OK to apply the halftone screen effect across the separate color channels.