From a user: hi, while testing your service i noticed that your system does not show me -90 in the json result. it always shows “90” and that is no help because I don´t know how I need to rotate the image based on the text. is there any other way to get the information, how I need to rotate the image so a human is able to read the text 
thanks !
The solution is easy: -90° means a counter-clockwise rotation of 90°. In this case the OCR API returns a “TextOrientation” angle of 270°, which is the same as -90°.