OMR sheet reader for mobile app

I'm looking for an experienced Freelancer to develop an OMR sheet reader for a mobile app. The OMR sheets used will be customized and the accuracy required for reading the OMR sheets will be high (above 95%). The mobile app should be able to read and process the OMR sheets (example sheet is attached). No cloud processing is allowed. The result is a JSON with the answers. Programming language compatible with Flutter. If you have the ability to develop this kind of technology and provide a quality service, I would like to hear from you. Thank you.