GIMP Layer Effects for GIMP 3

Layer styles for GIMP 3, as in other image editors: drop shadows, glows, bevels, satin, strokes and overlays, each built as a layer of its own with its own blend mode and opacity, next to the layer it belongs to. The settings stay with the effect, so that the effects can be rebuilt after the layer has changed (a text edited, a shape repainted).

This is a port of GIMP Layer Effects by Jonathan Stipe (layerfx.2.8.py, 2008 to 2012), from the old GIMP Plugin Registry (registry.gimp.org/node/186, mirrored at github.com/earl-kent/layerfx), to GIMP 3 and Python 3. The original is kept unchanged in original/layerfx.2.8.py. Like it, this port is free software under the GNU General Public License, version 3 or later.

The effects

All are in Layer > Layer Effects and in the context menu of the Layers dialog (Layer Effects):

Effect	Makes	Mode
Drop Shadow	a shadow below the layer, moved away from the light	Multiply
Inner Shadow	a shadow inside the layer's edge, from the edge or the centre	Multiply
Outer Glow	a glow around the layer, in a colour or a gradient	Screen
Inner Glow	a glow inside the edge, in a colour or a gradient	Screen
Bevel and Emboss	a highlight and a shadow layer: outer and inner bevel, emboss, pillow emboss, with a texture	Screen, Multiply
Satin	satin like shading inside the layer	Multiply
Stroke	an outline inside, centred on or outside the edge, in a colour, a gradient or a pattern	Normal
Color Overlay	a colour over the layer's shape	Normal
Gradient Overlay	a gradient over the layer's shape	Normal
Pattern Overlay	a pattern over the layer's shape	Normal
Reapply Effects	rebuilds all effects of the layer with their settings

Mode is the default blend mode. The options are those of the original: opacity, blend mode (21 modes), size, spread or choke, contour (12 curves), noise, angle and distance, knockout, and Merge with layer, which merges the effect into the layer instead of making a layer of its own (it cannot be reapplied then). Preview in each dialog builds the effect in the image while the dialog is open.

How the effects are built

The layer and its effect layers go into a layer group named <layer>-with-effects, in Pass Through mode, so that each effect blends with the image below it: a Multiply shadow darkens the background, a Screen glow lightens it. (GIMP 3's own filters have a blend mode too, but it blends the filter's result with the layer the filter is on: GIMP 3.2's Drop Shadow filter in Multiply mode leaves the background as it was.) Effect layers are ordinary layers that can be painted on, masked, hidden or moved.

Inside the group the effects are kept in this order, top to bottom: Bevel and Emboss (highlight, then shadow), Stroke, Inner Shadow, Inner Glow, Satin, Color Overlay, Gradient Overlay, Pattern Overlay, the layer, an outside Stroke, Outer Glow, Drop Shadow. An effect applied again replaces the old one where it is, also if you moved it.

The settings of each effect are stored on its layer (a parasite named layerfx-effect, as JSON), and are saved in XCF files. Opening an effect's dialog for a layer that has that effect shows its settings. Reapply Effects rebuilds every effect of the layer with them, for example after editing a text layer. Any of the layer, its group or one of its effect layers can be selected for this, or for adding an effect.

The effects work on RGB and grayscale images of every precision (8, 16 and 32 bit integer, 16 and 32 bit floating point, linear or perceptual), on layers with offsets, with layer masks (the mask is part of the shape) and on text layers. Drop Shadow, Outer Glow, Bevel and Emboss, Satin and Stroke need a layer with an alpha channel, as in the original; for a layer without one they say so and change nothing.

Differences from layerfx 2.8

• One group per layer. 2.8 wrapped the layer and the new effect in a new group (Normal mode) for each effect applied, so several effects nested groups in the order they were applied. Here there is one Pass Through group per layer, in a fixed order (see above).
• Ramps without steps, in one go. 2.8 built the gradual edges of shadows, glows and bevels by growing or shrinking the selection one pixel at a time and filling each step with the next grey, which is slow for large sizes and gives an 8-bit staircase. Here the same ramps come from a Euclidean distance transform of the layer's alpha (gegl:distance-transform), computed in floating point in the plug-in and written to the image once. They are straight lines through the corners of the old staircase: on discs and rectangles they are within 0.22 of a step of the original on average, 0.66 of a step at most (tests/cases/15-ramp.py). An effect on a 12 megapixel layer takes about 3 to 5 seconds. The effects are not clipped to the canvas, as the selection was.
• Contours in floating point. The contour curves are the original's points and tables; the smooth ones are computed with GIMP's curve algorithm (identical to GIMP 3.2's Curves, tested) and applied to the plain mask values, as 2.8 applied them to 8-bit masks. (GIMP 3's Curves would apply them to perceptual values instead.)
• GIMP 3 means for the removed procedures. gegl:bump-map replaces plug-in-bump-map, gegl:noise-hsv plug-in-hsv-noise, gegl:gaussian-blur plug-in-gauss-rle (with the same radius), Gimp.GroupLayer gimp-layer-group-new, and the bounds of the satin are computed instead of plug-in-autocrop-layer. Gradient glows map the gradient's colours (and alpha) directly instead of plug-in-gradmap.
• Blend modes. The 21 modes of the original are GIMP 3's modes of the same names (not the "legacy" ones); they blend in linear light, so results can look slightly different from GIMP 2.8.
• Arguments. Procedures are named python-layerfx-drop-shadow and so on (2.8: python_layerfx_drop_shadow, and a copy python_layer_fx_drop_shadow for the Layers dialog; GIMP 3 has one procedure with both menus). The blend mode, contour, source, style, direction, gradient type, repeat and interpolation are choices by name ("multiply", "gaussian", ...) instead of numbers. 2.8's colour argument that could also be a gradient name (glows) or a tuple (strokes) is split into fill-type, color, gradient, gradient-type and so on; these new arguments come after the old ones. The interpolation "Sinc (Lanczos3)" is NoHalo, which replaced Lanczos in GIMP 2.10.
• Semi-transparent layers. 2.8's partly selected fills gave uneven results for layers that are partly transparent throughout. Here the shape's edges are those of its alpha divided by its local maximum, and the effects that reach outside the layer take its alpha level: a layer at 50 % gets a shadow at 50 %. Knockout removes the shadow or glow under the whole layer (2.8 filled black through the layer's alpha, which only halves it under a layer at 50 %). For opaque layers with antialiased edges nothing changes.
• Fixes. A pattern stroke outside the layer is not cut off at the layer's bounds; a shaped gradient (angular, spherical, dimpled) in the Gradient Overlay is not applied twice to the alpha at the edges; merging keeps effects that reach out of the layer (GIMP 3 would clip Screen or Multiply layers to the layer below when merging down).
• Reapply finds the effects in the group by their parasites. 2.8 stored the effect layer's name on the layer and looked it up among the image's top-level layers. Reapply keeps hidden effect layers hidden and the order you gave them; the group and the effect layers take the layer's new name (text layers are renamed after their text). The parasites are saved with the image (2.8's were not persistent).
• Preview starts off each time (it builds the effect, which takes a moment on large layers); the undo history is frozen meanwhile, and the preview layers are removed on Cancel. The whole effect is one step in the undo history.
• Refusals are messages, never tracebacks: an indexed image, a layer group that is not an effects group, a channel, or a layer without alpha for the effects that need one. A layer mask selected stands for its layer.
• Noise comes from gegl:noise-hsv, with a new random pattern each time the effect is built, as in 2.8.

Install

The plug-in is the folder layerfx/ with the Python file layerfx.py in it. It needs GIMP 3 with Python 3 plug-ins; it is tested with GIMP 3.2.6, the Flatpak org.gimp.GIMP from Flathub, which has them.

GIMP 3 installed natively: copy the folder into the plug-ins folder of your GIMP profile and make the file executable, then restart GIMP:

mkdir -p ~/.config/GIMP/3.2/plug-ins
cp -r layerfx ~/.config/GIMP/3.2/plug-ins/
chmod +x ~/.config/GIMP/3.2/plug-ins/layerfx/layerfx.py

On Windows the folder is %APPDATA%\GIMP\3.2\plug-ins\, on macOS ~/Library/Application Support/GIMP/3.2/plug-ins/. Edit > Preferences > Folders > Plug-ins in GIMP shows the folders it reads.

The Flatpak (org.gimp.GIMP): it uses the same profile folder, ~/.config/GIMP/3.2/plug-ins, so the commands above work for it too.

The folder name and the file name must stay layerfx. Uninstall by removing the folder.

Tests

tests/run.sh

runs GIMP without a window, with a throwaway profile in tests/output/ (your own GIMP profile and plug-ins are not used or changed), and prints PASS or FAIL for each case; it exits non-zero if a case fails or the plug-in printed a traceback or a warning. It needs no network and no display. The cases (in tests/cases/) check:

• that every procedure is registered with the arguments of the original, in its order, with its ranges, defaults, menus and image types;
• the ramps against the original's grow-by-one-pixel loop, run with GIMP 3's own Grow and Shrink, and the contour curves against GIMP's Curves;
• each effect on an opaque disc on a transparent layer: the layers made, their order, blend mode, opacity and size, and their pixels (the direction and distance of shadows, glows outside only and inner effects inside only, the three stroke positions, knockout, spread, contour, noise, satin, overlays only over the shape, the highlight and shadow of each bevel style on the right sides for the light, and effects blending with the image below);
• Merge with layer for every effect, with and without a layer mask;
• Reapply after the layer changed (the same settings, the new shape, the order kept), from the layer, its group or an effect layer, and after saving and loading an XCF;
• every precision in RGB and grayscale against a floating point result, layers with offsets, layers with masks (also switched off), layers in layer groups;
• every blend mode, contour, gradient type, repeat and interpolation, and every effect with its settings at the ends of their ranges;
• the preview (without the dialog): built, and the image exactly as before afterwards;
• the refusals, the selection and context being left as they were;
• a text layer, whose text is changed before Reapply (in a second GIMP that loads fonts: GIMP 3.2 can hang loading fonts, so a hang there is reported as SKIP);
• the time taken on a 1200 x 800 layer.

When a headless Chrome (or Chromium) and node 22 are there, run.sh also runs tests/gui/gui-test.sh: GIMP on a Broadway display, driven through gimp-devtools' gui/cdp.mjs (expected next to this folder, or in $GIMP_PLUGIN_DEVTOOLS). It opens the Drop Shadow dialog, turns Preview on and presses OK (one shadow is made) or Cancel (the preview is removed), opens it on a layer that has a drop shadow (the dialog shows that shadow's settings), and presses Ctrl+Z after an effect (the image is as before, after one undo). On Broadway the keys of a GIMP session sometimes reach none of its windows; the undo session is then repeated (up to 6 times), while a wrong result after an undo fails at once. Screenshots are left in tests/output/gui/. tests/gui/look.sh <effect> opens any effect's dialog and takes a screenshot of it.

LFX_ONLY=stroke tests/run.sh   only the cases whose names contain "stroke"
LFX_GUI=0 tests/run.sh         without the Broadway tests
GIMP_FLATPAK=0 tests/run.sh    with a native gimp-console-3.2 or gimp-console

License

GPL version 3 or later, see COPYING.

GIMP Layer Effects
Copyright (c) 2008 Jonathan Stipe
Copyright 2026 David, port to GIMP 3