android-ocr | Experimental optical character recognition app | Computer Vision library

Starting with this sample project [ https://github.com/googlesamples/android-vision/tree/master/visionSamples/ocr-reader ], I have been able to implement filtering in the OcrDetectorProcessor.receiveDetections() method.

This works, but com.google.android.gms.vision.text.TextRecognizer appears to search the the entire screen for characters.

I presume that the receiveDetections() method could be called more frequently if a smaller portion of the screen were being scanned for characters instead of the entire screen.

Is it possible to specify a smaller portion of the screen to be scanned? It should be straight-forward to direct the user, through a change to the graphic overly, to position their camera so that this smaller portion of the screen contained the target text, but I'm unsure as to how to tell the processor to use just a small portion of the frame when doing it's OCR processing.

What would need to be altered to specify that the OCR should operate on a subset of the frame?

ADDITIONAL INFORMATION:

I tried to subclass TextRecognizer, but it's marked final, and the source appears to be closed.

So I'm expanding the question to how the functionality of the ocr-reader sample could be replicated using Tesseract.

I found this link, but haven't explored converting the concepts there into camera frames as opposed to a single image file.