Using the Smudge Tool in GIMP

The Smudge tool in GIMP picks up the color under the cursor and drags it in the direction you paint - like smearing wet ink. It is useful for softening harsh edges, blending colors in digital paintings, creating hair or fur textures, and smoothing rough selections. Here is how to use it well.

Activating the Smudge Tool

Press S to activate the Smudge tool. Click and drag on the canvas to smear pixels in the drag direction.

The Smudge tool does not use the foreground color. It only moves existing pixels. If you drag from a blue area into a white area, the blue spreads into the white. The longer you drag in one direction, the further the color pulls.

The Rate Setting - Most Important Control

In Tool Options, the Rate slider controls how strongly pixels are pushed:

• Low rate (10-30%): Gentle, subtle smudge. Moves pixels only a little. Good for softening transitions.
• Medium rate (50-70%): Obvious blending effect. Colors pull visibly into each other.
• High rate (80-100%): Aggressive smear. Pushes color far in one direction. Good for painting hair strands or creating streaks.

Start at 50% and adjust from there. Very high rates can over-smear and destroy detail. Very low rates can be too subtle to see. The Rate works together with your stroke speed - slower strokes at the same rate smear more than fast strokes.

Blending Colors and Edges

The Smudge tool is useful for:

• Softening selection edges: After cutting out a subject with a hard selection, use Smudge with a low rate to blend the edge pixels into the new background more naturally.
• Blending paint strokes: In digital painting, Smudge can merge two adjacent color strokes into a smooth gradient, similar to blending oil paints.
• Hiding seams: When cloning or retouching a photo, small visible seams between the original and patched areas can be blended with a light Smudge pass.

Use a soft brush (low hardness) for smoother smearing and a hard brush for more directional color pushing with defined edges. For edge softening specifically, the edge cleanup guide covers the Smudge tool alongside other techniques for refining cutout edges.

Creating Hair and Fur Effects

The Smudge tool with a small, hard, slightly oval brush at high rate creates convincing hair strand effects:

1. Set brush size to 2-4px with high hardness.
2. Set Rate to 70-85%.
3. Make short, quick strokes at the edge of a hair or fur area, pulling outward from the subject.

Each quick outward stroke creates a thin hair-like streak. Vary the stroke length and direction slightly for a natural result. This is especially useful for improving background removal on portraits where the original selection cut off some hair strands.

Smudge vs. Blur - When to Use Each

Smudge preserves more of the pixel color information by moving it rather than averaging it. Blur makes everything softer but can look unnatural on features with directional detail like hair or fabric weave. For portrait retouching, Smudge is better for hair and Blur is better for skin.