The core Qt Gui library by default supports reading and writing image files of the most common file formats: PNG, JPEG, BMP, GIF and a few more, ref. Reading and Writing Image Files. The Qt Image Formats add-on module provides optional support for other image file formats.

Qt supports several file formats by default, and in addition new formats can be added as plugins. The currently supported formats are listed in the QImageReader and QImageWriter class documentation. Qt's plugin mechanism can also be used to write a custom image format handler.

Qt provides four classes for handling image data: QImage, QPixmap, QBitmap and QPicture. QImage is designed and optimized for I/O, and for direct pixel access and manipulation, while QPixmap is designed and optimized for showing images on screen. QBitmap is only a convenience class that inherits QPixmap, ensuring a depth of 1.

libpng is the official PNG reference library. Used in the qpng image plugin. Configure with -system-libpng or -no-libpng to avoid. The sources can be found in qtbase/src/3rdparty/libpng. Project Homepage, upstream version: 1.6.47

For sizes up to 16 x 16, QIcon uses qt_extended_16x16.png and scales it down if necessary. For sizes between 17 x 17 and 32 x 32, it uses qt_extended_32x32.png . For sizes above 32 x 32, it uses qt_extended_48x48.png .

The Image component is used for adding images to the UI in several supported formats, including bitmap formats, such as PNG and JPEG, and vector graphics formats, such as SVG.

Images can be supplied in any of the standard image formats supported by Qt, including bitmap formats such as PNG and JPEG, and vector graphics formats such as SVG. If you need to display animated images, use AnimatedSprite or AnimatedImage .

Since Qt 6.7, Qt also provides access to the native icon library on macOS, iOS, and Windows 10 and 11. On Android, Qt can access icons from the Material design system as long as the MaterialIcons-Regular font is available on the system, or bundled as a resource at :/qt-project.org/icons/MaterialIcons-Regular.ttf with the application.

For example, the PNG format allows you to embed text into the image's metadata (see text()), and the BMP format allows you to determine the image's size without loading the whole image into memory (see size()).

The : prefix makes it explicit that "/images/cut.png" should be loaded from the Qt Resource System. You can also reference the Qt resource system through a QUrl . Use the qrc scheme in this case: