Thanks for the explanation, I do see where you are going with this.
Ignition can certainly do what you need it to do, but I would recommend at looking into other avenues. Specifically, I would consider leveraging cloud services such as Azure or AWS to offload the image processing outside of your Ignition Gateway.
There are already tools within these platforms to do OCR; one example is Amazon Rekognition (https://docs.aws.amazon.com/rekognition/latest/dg/text-detection.html). You can interface from Ignition using their API endpoints and get your data into historian (if historian is were you need them to go ultimately)
Exciting project! Keep me posted on the progress.
Cheers,
Oscar.