Detect text orientation

Question

How to detect text orientation in an image? It doen't matter if the orientation is upside down (180 deg).. But if the text lines is vertical (90 or 270 deg) I need to rotate it 90 degrees. I hope its possible without OCR because it takes too much resources to process OCR on 4 different orientations of the same image The reason is that I use scantailor on images from a digital camera or smart phone and if the text orientation is 90 or 270 degree sometimes the image is cropped and text is lost JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

You can use the Hough Transform to detect the longest lines in your image and then find the predominant slope of those lines. If the slope is close to zero, your text is horizontal; if it's close to infinity, your text is vertical. You don't mention if you're using a library to do this, but in OpenCV you could use HoughLinesP. I used this tutorial on an image found on wikimedia: to get this image: Then I rotated the original image: to get this: Since you're only interested in horizontal or vertical, you can just test whether the difference in the x-coordinates of the line endpoints is close to zero (vertical) or the difference in the y-coordinates is close to zero (horizontal).