Awesome C/C++

GUI

Graphic User Interface

• CEGUI - Flexible, cross-platform GUI library.
• FLTK - Fast, light, cross-platform C++ GUI toolkit. [GPL2]
• GacUI - GPU Accelerated C++ User Interface, with WYSIWYG developing tools, XML supports, built-in data binding and MVVM features. [Ms-PL]
• GTK+ - A multi-platform toolkit for creating graphical user interfaces. [LGPL]
• gtkmm - The official C++ interface for the popular GUI library GTK+. [LGPL]
• imgui - Immediate Mode Graphical User Interface with minimal dependencies. [MIT]
• libRocket - libRocket is a C++ HTML/CSS game interface middleware. [MIT]
• MyGUI - Fast, flexible and simple GUI. [MIT]
• QCustomPlot - Qt plotting widget without further dependencies. [GPLv3]
• Qwt - Qt Widgets for Technical Applications. [Own based on LGPL]
• QwtPlot3D - A feature-rich Qt/OpenGL-based C++ programming library, providing essentially a bunch of 3D-widgets. [zlib]
• PDCurses - Public domain curses library with both source code and pre-compiled library available. [PublicDomain]
• Sciter - Sciter is an embeddable HTML/CSS/scripting engine aimed to be used as an UI layer of modern desktop applications. [Free/Commercial]
• wxWidgets - A C++ library that lets developers create applications for Windows, Mac OS X, Linux and other platforms with a single code base. [Own LGPL]

Graphics

• bgfx - A cross-platform rendering library. [BSD]
• Cairo - A 2D graphics library with support for multiple output devices. [LGPL2 or Mozilla MPL]
• GLFW - A simple, cross-platform OpenGL wrangling library. [zlib/libpng]
• Horde3D - A small 3D rendering and animation engine. [EPL]
• Irrlicht - A high performance realtime 3D engine written in C++. [zlib]
• magnum - C++11 and OpenGL 2D/3D graphics engine. [MIT] website
• Ogre 3D  - A scene-oriented, real-time, flexible 3D rendering engine (as opposed to a game engine) written in C++. [MIT]
• OpenSceneGraph - An open source high performance 3D graphics toolkit. [OSGPL]
• OpenSubdiv - Pixar‘s library for evaluating and rendering subdivision surfaces on CPU and GPU. [Modified Apache2]
• OpenVDB - Library and tools for storing, editing, and rendering volumetric datasets. [MPL2]
• Panda3D - A framework for 3D rendering and game development for Python and C++. [BSD]
• Partio - Library for wrangling particle data, with support for most common file formats. [Modified BSD]
• Skia - A complete 2D graphic library for drawing Text, Geometries, and Images. [BSD] webpage
• urho3d - Cross-platform rendering and game engine. [Many different, mostly MIT]

Image Processing

• Boost.GIL - Generic Image Library.
• CImg - A small, open source, C++ toolkit for image processing. [Own LGPL or GPL]
• CxImage - An image processing and conversion library to load, save, display, transform BMP, JPEG, GIF, PNG, TIFF, MNG, ICO, PCX, TGA, WMF, WBMP, JBG, J2K images. [zlib]
• FreeImage - An open source library that supports popular graphics image formats and others as needed by today‘s multimedia applications. [GPL2 or GPL3]
• GD - GD Graphics Library, famously used in PHP for image loading/manipulation & thumbnail generation. [custom permissive license, requires mention in user docs] website
• GDCM - Grassroots DICOM library.
• ITK - An open-source, cross-platform system for image analysis. [Apache2 from ITK 4.0]
• libvips - A fast image processing library with low memory needs. [LGPL] website
• Magick++ - ImageMagick program interfaces for C++. [Apache2]
• MagickWnd - ImageMagick program interfaces for C. [Apache2]
• OpenCV  - Open source computer vision. [BSD]
• OpenEXR - Cross-platform library for high dynamic range imaging. [Modified BSDF]
• OpenImageIO - Powerful image and texture wrangling library with support for a wide number of common lossy and RAW formats. [Modified BSD]
• tesseract-ocr - An OCR engine. [Apache2]
• Video++ - A C++14 high performance video and image processing library. [MIT]
• VIGRA - A generic C++ computer vision library for image analysis. [MIT X11]
• VTK - Open-source, freely available software system for 3D computer graphics, image processing and visualization. [BSD]

http://fffaraz.github.io/awesome-cpp/