Map Brush Size to Stylus Tilt in GIMP

Configuring GIMP to adjust brush size based on stylus tilt allows digital painters to create natural, calligraphic, and shading effects similar to traditional media. This guide explains how to use GIMP's Paint Dynamics Matrix to link your graphics tablet's tilt sensor directly to the brush size property, covering dynamic preset creation, matrix mapping, and tool application.

1. Ensure Hardware and Driver Support

Before configuring GIMP, confirm that your graphics tablet and stylus support tilt sensitivity (often listed as ±60° tilt). Ensure your tablet drivers are installed and functioning, and verify under Edit > Input Devices in GIMP that your stylus is recognized and set to Screen mode rather than disabled.

2. Create a Custom Paint Dynamic

Default paint dynamics in GIMP are locked and cannot be edited directly, so you must create a new preset:

  1. Open the Dynamics dock by navigating to Windows > Dockable Dialogs > Paint Dynamics.
  2. Click the Create a new dynamics icon (the blank sheet icon) at the bottom of the dialog, or right-click an existing dynamic and choose Duplicate Dynamics.
  3. Name your dynamic something descriptive, such as "Tilt Size Control".

3. Configure the Dynamics Matrix

Once the new dynamic is created, the Paint Dynamics Editor will open automatically (or can be opened by double-clicking your new preset):

  1. Locate the Paint Dynamics Matrix, which displays tablet inputs (Pressure, Velocity, Direction, Tilt, Wheels, Random) along the horizontal axis and brush outputs (Opacity, Size, Angle, Color, Hardness, Force, Aspect Ratio, Spacing, Rate, Flow, Jitter) along the vertical axis.
  2. Find the row labeled Size.
  3. Trace across to the column labeled Tilt.
  4. Check the box at the intersection of Tilt and Size.

4. Adjust the Response Curve

By default, the mapping uses a linear curve. To customize how aggressively the brush scales relative to the stylus angle:

  1. In the Paint Dynamics Editor, expand the Size section at the bottom to view the mapping curve.
  2. Ensure the dropdown menu is set to Tilt.
  3. Click and drag the curve line to adjust the sensitivity:
    • A straight diagonal line provides a direct 1:1 proportional scaling.
    • Raising the curve increases size faster at shallow angles.
    • Inverting the line makes the brush larger when the pen is upright and smaller when tilted.

5. Apply the Dynamic to Your Brush Tool

  1. Select the Paintbrush, Airbrush, or MyPaint Brush tool from the Toolbox.
  2. Go to the Tool Options dock.
  3. Locate the Dynamics section.
  4. Click the dynamic icon and select your newly created "Tilt Size Control" dynamic from the list.
  5. Set your base brush size in the Tool Options. When you draw, tilting the stylus will dynamically adjust the active stroke size relative to this base value.