Request - Add the ability to put bounds around where you want to try to perform OCR on your image source

[SoulManGG]

I have found that the way to do that is via the following command

// tf->tesseract_model->SetRectangle(left, top, width, height);
tf->tesseract_model->SetRectangle(0, 490, 300, 100); // <- for Example

What I cant figure out how to do is how to make all the changes to support this. This would be great for me. Thank you! I will probably keep working to figure out how to make it work but I am struggling with the github make system and how to make an install or even just compile this stuff to test the changes I made in my fork.