Tensorflow Api How can I make it detect only the text shown in the frame in real-time object detection?

[ruzgarkanar]

Hi guys, Help me please Hi I will read text with the model I trained in tensorflow, but I don't want it to read the text I hold in the rectangle and detect it everywhere, how can I do it? for example look at picture. I want to do the same as when reading Whatsapp qr code. So I want to have such a rectangle in the real time camera and I want it to detect only when I bring the text on the paper to that square.