I am working on an OCR project and I wonder how I can calculate the confidence score of my OCR system.
I have digital multi meter images. There are some measurement results on the screens of devices in images. I want to recognize those values. However, according to my research, I am not sure which OCR confidence calculation technique is fit for my system.
As I understand OCR confidence scores can calculate in character, word and sentence wise. Actually, the last two methods build on character confidence scores. In my case, character wise calculation might be wrong or not sufficient.
For example, I have "40.245 V" text. I got two different recognition result like "40.247 V" and "70.245 V". If I am not wrong both of the result will have same or close confidence scores. Yet "40.247 V" prediction is acceptable and "70.245 V" is not acceptable in my case.
Is there any idea how to calculate confidence score for this case?