The text API implements the algorithm that was proposed by Lukás Neumann and Jiri Matas in the article Real-Time Scene Text Localization and Recognition during the computer vision and pattern recognition (CVPR) conference in 2012. This algorithm represented a significant increase in scene text detection, performing state-of-the art detection both in the CVPR database, as well as in the Google Street View database. Before using the API, let's take a look at how this algorithm works under to hood, and how it addresses the scene text detection problem.
Remember: The OpenCV 4.0 text API does not come with the standard OpenCV modules. It's an additional module that's present in the OpenCV contrib package. If you installed OpenCV using the Windows Installer, you should take a look back at Chapter 1, Getting Started with OpenCV; this will guide you on how to install these modules.