ft — Fourier space exploration

A Qt6-based interactive viewer for images and their 2D Fourier transforms. Supports MRC, TIFF, JPEG and PNG image formats.

Features

• Load and display images with pixel-coordinate axes
• Compute and display the 2D FFT with animated progress
• Four display modes: cosine/sine, amplitude/phase, power spectrum, complex (phase-colored) Fourier transform
• Axis labels in both pixel and physical units (Angstrom / reciprocal Angstrom)
• Mouse-wheel zoom on any displayed image, with axes that update to the visible region
• Grey-value histograms below each displayed image
• Live pixel-value readout under the mouse cursor
• MRC file support with automatic byte-order detection and header debug output
• Optional center-masking of the Fourier transform for display

Requirements

• C++17 compiler (GCC >= 8, Clang >= 7, or MSVC >= 2017)
• CMake >= 3.16
• Qt 6 (Widgets module)

Installing dependencies

macOS

Install Qt 6 and CMake via Homebrew:

brew install qt@6 cmake

If CMake cannot find Qt, point it to the Homebrew prefix:

export CMAKE_PREFIX_PATH="$(brew --prefix qt@6)"

Ubuntu (22.04 / 24.04)

sudo apt update
sudo apt install build-essential cmake qt6-base-dev

On Ubuntu 22.04, if qt6-base-dev is not available in the default repositories, add the official Qt PPA or install from the Qt online installer.

Windows

1. Install Qt 6 using the Qt online installer. During installation, select the Qt 6.x component matching your compiler (MSVC or MinGW). Note the installation path (e.g. C:\Qt\6.8.3\msvc2022_64).

2. Install CMake from cmake.org or via winget install Kitware.CMake. Make sure CMake is on your PATH.

3. Install a C++17 compiler — either:

   • MSVC: Install Visual Studio 2019 or later with the "Desktop development with C++" workload, or
   • MinGW: Use the MinGW build shipped with Qt (selected during Qt installation).

Building

macOS / Linux

mkdir build
cd build
cmake ..
cmake --build .

The executable ft will be created in the build/ directory.

Windows with MSVC

Open a Developer Command Prompt for Visual Studio (or "x64 Native Tools Command Prompt") and run:

mkdir build
cd build
cmake .. -DCMAKE_PREFIX_PATH=C:\Qt\6.8.3\msvc2022_64
cmake --build . --config Release

Replace the CMAKE_PREFIX_PATH with the actual path to your Qt installation. The executable ft.exe will be created in build\Release\.

Windows with MinGW

Open a terminal and make sure the MinGW bin directory shipped with Qt is on your PATH:

set PATH=C:\Qt\Tools\mingw1310_64\bin;%PATH%
mkdir build
cd build
cmake .. -G "MinGW Makefiles" -DCMAKE_PREFIX_PATH=C:\Qt\6.8.3\mingw_64
cmake --build .

The executable ft.exe will be created in the build\ directory.

Running

On macOS or Linux:

./build/ft

On Windows:

build\Release\ft.exe

If ft.exe cannot find Qt DLLs at runtime, either add the Qt bin directory to your PATH or copy the required DLLs next to ft.exe. Qt provides the windeployqt tool to automate this:

C:\Qt\6.8.3\msvc2022_64\bin\windeployqt.exe build\Release\ft.exe

Use the Load image button to open an image file, then click the FT arrow to compute the Fourier transform.

WebAssembly (WASM) build

To build and deploy the application as a WebAssembly app that runs in a browser, see WASM_SERVER.txt for full instructions on installing Emscripten, the Qt WASM kit, and running a local web server.

License

See LICENSE for details.