CRTBender

Software geometry correction for CRT monitors on Windows. Your monitor bends the picture; CRTBender bends it back before it gets there. No hardware mods, no service menu. Separate builds support Windows 10/11 and Windows XP.

Features

• Corrects the whole picture, on every connected monitor.

• A 15x15 grid on top of that, for anything the sliders cannot reach.

• Sliders for the usual things first: rotation, pincushion, trapezoid, size, position, and separate top and bottom edge bows.

• Convergence correction, for coloured fringes on sharp edges.

• Remembers a separate setting for every monitor and every resolution.

• Built-in test grid to calibrate against.

• English and Hungarian.

Hotkeys

• Ctrl+Alt+B - correction on/off. Also the panic key.
• Ctrl+Alt+G - test grid on/off.
• Ctrl+Alt+E - open the calibration window.
• Esc - hide the test grid.

System Requirements

Requirement	Windows 10 / 11 Version	Windows XP Version (Legacy)
Operating System	Windows 10 (1809+) or Windows 11 (64-bit)	Windows XP SP2 (32-bit / x86)
Graphics API	Direct3D 11 (DXGI Desktop Duplication)	Direct3D 9 (GDI Capture)
GPU Hardware	DirectX 11 compatible GPU (Intel HD 4000+, GTX 400+, HD 5000+)	DirectX 9.0c GPU with Pixel Shader 2.0 support (e.g., Radeon 9000+, GeForce FX / 6 series+)
RAM	512 MB	128 MB
Dependencies	None (Portable, single .exe)	None (Portable, single .exe)

Note on Performance: The pixel shader transformation overhead is practically zero on any dedicated GPU (including GCN 1.0+ Radeon cards using CRT Emudriver at high resolutions like 1920x1440). Legacy pre-DX9 hardware without Pixel Shader 2.0 support is not supported.

Getting Started

1. On Windows 10/11, run CRTBender.exe. On 32-bit Windows XP SP2/SP3 with DirectX 9, use CRTBender-WinXP-x86.exe. Both live in the tray.
2. Press Ctrl+Alt+G to show the test grid.
3. On the Basic geometry tab, drag the sliders until the lines look straight. This does most of the work.
4. Use the Grid tab for whatever is left. Drag a point, or select one and nudge it with the arrow keys.
5. Press Ctrl+Alt+B a few times to compare before and after.
6. Close the window. Everything is saved automatically.

Double-click any slider or grid point to put it back to default, so an experiment is never a one-way trip.

Known Limitations

• Cannot draw over exclusive fullscreen games. Borderless windowed works.
• On Windows 10/11, CRTBender steps aside automatically for protected video.
• The XP build uses GDI capture and D3D9. It is lighter on old hardware but limited to bilinear filtering and usually runs at 30-60 FPS.
• The mouse cursor is not bent, so it can sit a pixel or two off in heavily corrected areas.

Building from Source

Requirements

• Visual Studio with Desktop development for C++
• For XP: the v141_xp toolset and a Win32 generator
• CMake 3.20+

Windows Build

# Windows 10/11 x64
cmake -B build -A x64
cmake --build build --config Release
# Output: build\Release\CRTBender.exe

# Windows XP x86
cmake -B build-xp -A Win32 -T v141_xp -DCRTB_XP=ON
cmake --build build-xp --config Release
# Output: build-xp\Release\CRTBender-WinXP-x86.exe

On Linux, ./tools/build.sh cross-builds and packages both editions.

Roadmap

• Per-corner RGB convergence controls
• Auto-calibration via photo / webcam with test pattern recognition
• Linux port (GLSL shader / Vulkan layer / Gamescope integration)
• Preset library for specific CRT models / TVs
• Linux port (GLSL shader / Vulkan layer / Gamescope integration) [High Interest]

About

Made by SubCoderHUN - https://github.com/SubCoderHUN/CRTBender