Draw a black bounding box on output image

[nikhilcms]

Hi @jasonlfunk,
It's a great repo which done decent job on most of the images, I observed that for some color images , it will make black bounding box(inside this text is present), may happen due to size of contour , instead of ((img_x * img_y) / 5) this if I set it to fixed number i.e 10,000(250dpi img) above problem were solved but if text height(colour heading) exceed above threshold and it will not make correct thresholding of that portion
Please let me know is there any robust way to solve above issue.
Thanks