Sticker turns any image into a floating, click-through desktop sticker with its
background removed by a local AI matting model — no uploads, no API keys, fully
offline after the one-time model download. Right-click an image in Explorer and
choose "Open as sticker": the subject peels off and hovers on your desktop, you
can drag it anywhere, transparent areas pass clicks through, and your stickers
come back exactly where you left them after a reboot.
README
Sticker
Turn any image into a floating desktop sticker with the background magically removed
✨ Why Sticker?
🖱️ One click
Right-click any image → Open as sticker. No extra apps, no export steps.
🧠 AI-powered
Background removal runs 100% locally on your GPU (or CPU).
👻 Click-through
Click pass-through on transparent layers.
💾 Remembers everything
Close your laptop, reboot, whatever - stickers come back where you left them.
> Every release is built in the open by GitHub Actions straight from this source, so you can verify exactly what's in it.
Build from source yourself
You'll need: Windows 11 • .NET 10 SDK • Developer Mode turned on (Settings → System → For developers)
Then just run:
.\setup_modern_menu.ps1
That's it! You'll see "Open as sticker" in your right-click menu on any image file.
> 💡 No Developer Mode? No problem — use the classic menu fallback instead:
>
>
>
> The entry will appear under "Show more options" in the context menu.
The first time you create a sticker, the AI model downloads automatically (~180 MB, one-time). After that, everything is instant and fully offline.
To uninstall, run .\setup_modern_menu.ps1 -Uninstall.
> 🧪 Contributing?dotnet test Sticker.slnx builds both projects and runs the unit tests (matte cache-key derivation, tolerant session parsing, the bilinear resize math, and the model registry). CI runs the same on every push/PR, and also checks that the version and the supported-image-extension list stay consistent across the installers and the MSIX manifest.
🎮 Using Stickers
Your cursor needs to be over the visible subject (transparent areas pass clicks through). Here's what you can do:
Action
What it does
🖱️
Drag
Move the sticker around
⬆️
Arrow keys
Nudge position 1px (Shift = bigger steps)
🔍
Scroll / +-
Resize (hold Ctrl for fine-tuning)
🌫️
Shift + scroll
Adjust opacity
🔄
R / Shift+R
Rotate 15°
↔️
F
Flip horizontal
👁️
D / double-click
Toggle between cutout and original
💾
S
Save cutout as PNG
❌
Esc / middle-click
Close sticker
📋
Right-click
Full menu (pin, always-on-top, re-matte…)
Tray Menu
Sticker lives in your system tray with quick access to:
Paste as sticker (Ctrl+Alt+V) — screenshot something, hit the hotkey, instant sticker
Open images… — pick files manually
Restore last session — bring back all your stickers from last time
Unpin sticker — release one pinned (click-through) sticker by name, or Unpin all stickers for the lot
Clear matte cache… — free up disk by deleting cached cutouts (open stickers and downloaded models are untouched)
Start with Windows — your stickers are always there when you log in
Not every background removal is perfect on the first try — so Sticker ships with three models you can swap between from a sticker's right-click menu (the "Matte: …" entries):
Model
Best for
Speed
Size
isnet-general-use
Everything (default)
⚡ Fast
~180 MB
u2net_human_seg
People & portraits
⚡ Fast
~180 MB
birefnet-general
Maximum quality
🐢 Slower
~900 MB
Each model's result is cached separately (~/.sticker_cache, keyed by image + model). Switching to a model you've already run loads instantly from that cache — no re-inference; a model you haven't tried yet runs once, then it's cached too. If you ever want a genuinely fresh pass, use "Re-process current (ignore cache)." Set a different default model with --model or the STICKER_MODEL environment variable. Restoring a session brings each sticker back with the model it was matted with when that cutout is still cached; otherwise it falls back to the default, so --resume never triggers a slow re-matte at login.
> 🐢 BiRefNet is heavy. It runs at 1024×1024 through a transformer backbone, so peak memory is several GB and it's much slower than the others. Two things can make it fail with an ONNX Runtime "out of memory" / "Failed to allocate" error even on a capable card:
>
> 1. DirectML is selecting the wrong GPU. This is the most common cause on machines with switchable graphics — see GPU selection in Troubleshooting. Fix that first; it's usually the whole problem.
> 2. DirectML genuinely overflows VRAM. DML's memory planning is less efficient than CUDA, so BiRefNet can need more than its nominal footprint. If you've confirmed the right GPU and it still won't fit, you can shrink the input resolution with STICKER_BIREFNET_SIZE=768 (or 512) to trade some edge detail for a smaller footprint, or accept the retry-on-CPU prompt (same result, just slower). STICKER_FORCE_CPU=1 always skips the GPU.
>
> The lighter isnet/u2net models run at 320–1024 px and rarely hit any of this.
🏗️ How It Works
sticker/
├── StickerApp/ → WPF tray app (the main show)
├── StickerShell/ → Explorer right-click menu integration
└── prototype/ → Original Python version (still works!)
StickerApp is a WPF app where each sticker is a borderless, transparent window with per-pixel alpha hit-testing — your clicks pass through transparent pixels for free. Background removal uses ONNX Runtime with DirectML (GPU acceleration on any DX12 graphics card, automatic CPU fallback). A single tray process keeps the model warm so subsequent stickers open instantly.
StickerShell is a COM server (IExplorerCommand) that puts "Open as sticker" in the top-level Windows 11 context menu — no "Show more options" submenu needed. Registered via a sparse package.
prototype/ is the original Python version (rembg + PyQt6). It shares the model folder (~/.u2net), matte cache (~/.sticker_cache), and session file with the C# app — useful as a test bench or if you prefer Python.
🛠️ Troubleshooting
Common fixes
Problem
Fix
NU1100 on first build
Your SDK is missing the NuGet feed. Run: dotnet nuget add source https://api.nuget.org/v3/index.json -n nuget.org
Package registration fails
Developer Mode is off. Turn it on in Settings → System → For developers.
Menu entry does nothing
Set env var STICKER_SHELL_LOG=1, restart Explorer, try again, then check %TEMP%\sticker-shell.log
Re-run .\setup_modern_menu.ps1 — the registration points at publish\, so don't move that folder
Stickers die when terminal closes
Don't use dotnet run — use the published exe (or launch via the context menu)
Model download stalls / corrupt
Delete the offending .onnx in %USERPROFILE%\.u2net and re-create a sticker to re-download (downloads are SHA-256-verified, so a corrupt file is auto-rejected)
Cutout looks stale after re-matte
Use the tray's "Clear matte cache…" (deletes only cached cutouts, keeps your session + models). Or use "Re-process current (ignore cache)" on the sticker itself.
Menu only shows for some image types
Old versions registered the classic menu under the image PerceivedType, which .webp (and others) often lack. Re-run install_context_menu.ps1 / reinstall — it now registers per-extension (.jpg .jpeg .png .webp .bmp .gif).
BiRefNet "out of memory" / "Failed to allocate"
Usually DirectML on the wrong GPU — see GPU selection. If the right GPU still won't fit: STICKER_BIREFNET_SIZE=768, take the CPU retry prompt, or STICKER_FORCE_CPU=1.
Heavy model fails, then lighter models fail too
Fixed in current builds — a failed session used to hold its VRAM. Update; if on an old build, restart Sticker to clear it.
Context menu placement (top-level vs. "Show more options")
Sticker can install its right-click entry two different ways, and which one you get depends on how you installed:
Install method
Where "Open as sticker" appears
How it's registered
.exe installer / winget
Under "Show more options" (classic)
A plain HKCU registry verb
setup_modern_menu.ps1 (build from source)
Top-level Win11 menu
An unsigned sparse app package (needs Developer Mode)
install_context_menu.ps1 (classic fallback)
Under "Show more options" (classic)
A plain HKCU registry verb
Why the difference? Windows 11 only lets an entry into the top-level context menu if it comes from an app package that implements IExplorerCommand (Microsoft deliberately closed the top-level menu to the old registry verbs to stop the Win10 clutter). That package has to be code-signed to install normally — an unsigned package only registers via Add-AppxPackage -Register with Developer Mode on, which is a developer convenience, not something you can ship to end users.
Sticker isn't code-signed yet (solo project, certs are pricey), so:
The shippable installers (the .exe and winget) fall back to the classic registry verb → lands under "Show more options". Installs cleanly for everyone, no Developer Mode needed.
The top-level menu currently only works via setup_modern_menu.ps1, which registers the unsigned package locally and therefore needs Developer Mode.
This is a limitation of not being signed, not a deliberate choice — both menus launch the exact same app. If/when Sticker ships a signed MSIX (e.g. via the Microsoft Store, which signs packages for you), the top-level menu can be the default everywhere.
If you've installed the .exe and want the top-level entry too, you can run setup_modern_menu.ps1 alongside it; the two registrations are independent (you'd then see both entries until you remove one).
GPU selection (hybrid graphics)
Sticker auto-selects the highest-VRAM adapter for DirectML, so hybrid-graphics machines should use the discrete GPU without any setup. (Earlier builds blindly used DXGI adapter 0 — and whichever GPU drives your primary display is normally adapter 0 — so on switchable-graphics systems they'd land on a low-memory integrated GPU and heavy models would OOM while the real card sat idle. That's now handled automatically.)
If a heavy model still fails with "out of memory" while your GPU clearly has free VRAM, the auto-pick may have chosen wrong — here's how to take control:
Force a specific adapter with STICKER_DML_DEVICE (the DXGI adapter index). Find the index of the GPU you want and set it explicitly — try 1 if 0 is the iGPU:
> Note the adapter index can change when your display setup changes. For example, after moving a monitor onto the dGPU, the dGPU becomes adapter 0 — so a previously-needed STICKER_DML_DEVICE=1 would then point back at the iGPU. Clear the variable once the dGPU is your primary display.
Environment variables
Variable
Effect
STICKER_MODEL
Default matting model for new stickers (e.g. birefnet-general). Same as --model.
STICKER_DML_DEVICE
Override the auto-selected DirectML adapter (DXGI index). Normally unnecessary — Sticker picks the highest-VRAM GPU automatically.
STICKER_FORCE_CPU
1 = skip the GPU entirely and run matting on the CPU (slow, but unlimited memory).
STICKER_BIREFNET_SIZE
BiRefNet input resolution (e.g. 768, 512); lower = less memory, less edge detail. Default 1024.
U2NET_HOME
Override the model download folder (default %USERPROFILE%\.u2net).
STICKER_SHELL_LOG
1 = write Explorer context-menu diagnostics to %TEMP%\sticker-shell.log.
Where Sticker keeps its files
Everything is per-user, under your profile folder — nothing is written to Program Files or HKLM. Paste these straight into Explorer's address bar:
What
Location
Notes
AI models
%USERPROFILE%\.u2net
One .onnx per model. Override the folder with the U2NET_HOME env var. Safe to delete — re-downloads on next use.
Matte cache
%USERPROFILE%\.sticker_cache
Cached cutout PNGs, keyed per image+model. Prefer the tray's "Clear matte cache…" over deleting by hand — the same folder also holds your session and clipboard captures (the latter auto-pruned to the most recent few).
Session
%USERPROFILE%\.sticker_cache\session.json
Positions/sizes of your open stickers — what --resume restores. Shared with the Python prototype. (Don't delete the whole .sticker_cache folder to clear cutouts — you'd lose this.)
Shell debug log
%TEMP%\sticker-shell.log
Only written when STICKER_SHELL_LOG=1 is set.
Registry entries
Sticker touches very little of the registry, and everything lives under HKEY_CURRENT_USER (no admin, no machine-wide keys). Open regedit and paste a path into its address bar to inspect.
Classic context-menu verb (only present if you used install_context_menu.ps1 / the classic fallback):
The \command subkey holds the exact launch line ("...\Sticker.exe" "%1") — handy for confirming the menu points at the right executable. Delete the OpenAsSticker key to remove the classic verb by hand.
Modern (Windows 11) context menu is not a plain registry verb — it's a sparse MSIX package registering an IExplorerCommand COM server. So you won't find it under shell\. Instead:
The COM registration is owned by the package and disappears with it — don't hand-edit it.
Autostart is deliberately not a ...\CurrentVersion\Run key (that location is malware's favourite, so Defender scores writes to it harshly). Instead it's a plain shortcut in your Startup folder:
The shortcut launches Sticker.exe --resume. To toggle it: use the tray menu's "Start with Windows", or just create/delete that .lnk yourself (type shell:startup in Explorer to open the folder).
Deeper diagnostics
Right-click menu misbehaving? Set the user env var STICKER_SHELL_LOG=1, restart Explorer (taskkill /f /im explorer.exe & start explorer.exe), reproduce, then read %TEMP%\sticker-shell.log — it traces each IExplorerCommand call.
Verify the modern package is actually registered:Get-AppxPackage *Sticker* | Format-List Name, PackageFullName, InstallLocation. If InstallLocation no longer exists (e.g. you moved/deleted publish\), the menu silently breaks — re-run setup_modern_menu.ps1.
GPU vs CPU matting: Sticker uses ONNX Runtime with DirectML and falls back to CPU automatically. If matting is unexpectedly slow, your GPU path may be falling back — check the tray app's console/output, and confirm a DX12-capable GPU and current drivers.
Force a model from scratch: delete its .onnx from %USERPROFILE%\.u2netand clear %USERPROFILE%\.sticker_cache so no stale cutouts are served.
Full reset (nuke everything user-side): uninstall the app, then delete %USERPROFILE%\.u2net, %USERPROFILE%\.sticker_cache, the Sticker.lnk startup shortcut, and (if you used the classic menu) the HKCU\...\OpenAsSticker registry key.
