Please accept a fact is that C++ is a programming language. Just like any natural language like English. Libraries, toolkits, frameworks can provide ready made or programmable solutions for the problem which are made using the programming languages like C++.
Image processing is a vast subjects and people make solutions themselves to an extend. Just to open an image, you can use Windows APIs or classes to load the image file. But if you really wanted to do some image processing (Ain't sure to what extend you're doing 'image processing'), it's better to rely on some libraries like OpenCV