Cam Tweak

Cam Tweak reads your real webcam, edits the picture and hands the result to Teams and other video apps as the camera "CamTweak".

• Size and position: scale the picture down (50–100 %, anchored at the bottom center) and move it, with sliders or by dragging in the preview.
• Background: cut out the person (AI, locally on the graphics card) and blur the background, fill it with a solid color (e.g. green for chroma key) or replace it with your own picture.
• Empty room: record the room once without yourself in it; this makes the edges of the cut-out more accurate and keeps the blur free of "ghost images".
• Color: brightness, contrast, saturation, color temperature.

Everything runs locally, without a cloud and without an account.

Install

Open PowerShell and paste this line:

powershell -c "irm https://applirado.github.io/camtweak/install.ps1 | iex"

It downloads the setup of the latest release and runs it; Windows asks once for admin rights, because the virtual camera is registered for the whole PC. Run the same line again to update. Remove Cam Tweak under Settings > Apps.

You can also download CamTweak-<version>.msi from the releases page, for example to distribute it with Intune. It is not signed yet, so when you open it from the browser, SmartScreen asks first: choose More info > Run anyway.

Requirements: Windows 11 (64-bit), a webcam, about 40 MB of disk space. The cut-out runs on a DirectX 12 graphics card or, more slowly, on the CPU.

Usage

• Cam Tweak runs in the notification area of the taskbar (next to the clock).
• Left-click the icon: preview and settings in three tabs (Picture, Color, Background). Double-clicking the preview centers the picture, double-clicking a slider resets it. Ctrl + Plus/Minus/0 or Ctrl + mouse wheel zooms the window.
• Right-click: "Start with Windows" and "Exit".
• In Teams, select "CamTweak" under Settings → Devices → Camera. If you use Cam Tweak's cut-out, turn off the background effect in Teams.
• The real camera is only open while a program uses "CamTweak" or the preview is open.
• The UI follows the Windows display language (German, otherwise English).

Tip: For the empty room, set the camera's exposure, white balance and focus to manual and record the room the way it normally looks (chair in its place, just without yourself).

Building

Prerequisites: Visual Studio 2022 with Desktop development with C++ (toolset v143), Windows 11 SDK.

MSBuild.exe CamTweak.sln -t:restore -p:RestorePackagesConfig=true
MSBuild.exe CamTweak.sln -p:Configuration=Release -p:Platform=x64

Output in bin\Release: CamTweak.exe, CamTweakSource.dll, ONNX Runtime (onnxruntime*.dll), DirectML.dll and models\selfie_segmenter_landscape.onnx.

For development, scripts\install.cmd installs the build output from bin\Release like the setup does (as administrator), and scripts\uninstall.cmd removes it again. Don't mix them with the setup on one machine.

Setup

Prerequisite: .NET SDK 8 or later (WiX Toolset v5 is restored from NuGet). After the Release build:

dotnet build installer -c Release

Output: bin\Release\installer\CamTweak-<version>.msi. One package for English and German; Windows picks the language from the display language. It installs to C:\Program Files\CamTweak, registers the virtual camera and creates a Start menu shortcut. Uninstalling also removes the autostart entry and the settings of the uninstalling user; installing a newer version replaces the old one and keeps the settings.

Releases

The version is set in src\Shared\Version.h, for the binaries and the setup; raise it for every release. Pushing a tag v<version> runs release.yml: it builds the setup from the tagged code, tests installing and removing it on a clean Windows and attaches it to a draft release. Write the release notes, then publish the draft. The website in website/ is published by pages.yml on every push to main.

Structure

Part	Purpose
src/CamTweak	Tray app (Win32, C++20): reads the camera (Media Foundation), cut-out, background, color, size/position, UI, starts the virtual camera (MFCreateVirtualCamera)
src/CamTweakSource	Media Foundation source (COM DLL) loaded by the Windows camera service; delivers the frames to Teams & co. (NV12/RGB32, 1080p/720p/360p, 30 fps)
src/Shared	Exchange format between the two (file mapping at %ProgramData%\CamTweak\frame.bin with a sequence lock), image functions and the version
models	MediaPipe Selfie Segmenter as ONNX
installer	MSI setup (WiX v5)
install.ps1	The one-line install: downloads and runs the setup of the latest release
website	The project page at https://applirado.github.io/camtweak/

Important files in src/CamTweak:

File	Contents
CameraPipeline.cpp	Opening the camera, per-frame image processing, compositing, handing over to the virtual camera
Segmenter.cpp	AI cut-out with ONNX Runtime (DirectML, otherwise CPU)
RoomMatte.cpp	Refining the mask with the recorded empty room
ColorAdjust.h	Brightness, contrast, saturation, color temperature
Popup.cpp	Window with preview, tabs and sliders
Strings.h	All texts (German/English)

The DLL runs in the camera service (session 0, LOCAL SERVICE) and cannot see named objects of the user session; hence the exchange through a shared file mapping. Settings are stored in HKCU\Software\CamTweak, the recorded empty room in %LOCALAPPDATA%\CamTweak\room.png.

Troubleshooting

• Intermediate images: create an empty file %LOCALAPPDATA%\CamTweak\dump.flag while the camera is running. Cam Tweak then saves the camera picture, AI mask, comparison with the empty room, final mask and result as PNGs next to it, plus info.txt (model, GPU/CPU, timing).
• Outliers: %LOCALAPPDATA%\CamTweak\events.log logs gaps in the camera stream, very slow frames and camera and cut-out errors.
• Camera DLL: writes ETW traces (provider GUID e43fec3f-98a3-438b-a7ba-45a7aa8ced45), readable e.g. with WpfTraceSpy. Detailed traces are only available in the Debug build.

License

Cam Tweak is released under the MIT License. For the components it builds on and ships, see third_party/NOTICES.md.