...
The OCR is trainable in order to support even special fonts (embossed, dotted, etc.), rotated texts, good performance on more variable backgrounds, and other things which general pre-trained OCR models can't usually offer.
...
Training
Annotations
For training, you draw rectangles in the image and can rotate them using the dot square connected to the top side of the rectangle. When a rectangle is selected, you can write the text it contains to the text field on the right.
...
You can also extend an already trained model.
...
Evaluation
Evaluation is done based on regular expressions (regex) - each found word/letter is tested, whether it matches the regex. If the regex is found at least in one word/letter, the image is marked as True.