Building an Image Viewer

Computer vision is the technology that enables computers to achieve a high-level understanding of digital images and videos, rather than only treating them as bytes or pixels. It is widely used for scene reconstruction, event detection, video tracking, object recognition, 3D pose estimation, motion estimation, and image restoration.

OpenCV (open source computer vision) is a library that implements almost all computer vision methods and algorithms. Qt is a cross-platform application framework and widget toolkit for creating applications with graphical user interfaces that can run on all major desktop platforms, most embedded platforms, and even mobile platforms.

These two powerful libraries are used together by many developers to create professional software with a solid GUI in industries that benefit from computer vision technology. In this book, we will demonstrate how to build these types of functional application with Qt 5 and OpenCV 4, which has friendly graphical user interfaces and several functions associated with computer vision technology.

In this first chapter, we will start by building a simple GUI application for image viewing with Qt 5.

The following topics will be covered in this chapter as follows:

• Designing the user interface
• Reading and displaying images with Qt
• Zooming in and out of images
• Saving a copy of images in any supported format
• Responding to hotkeys in a Qt application