def detect_text(path):
    """Detects text in the file."""
    
    import io, os
    from google.cloud import vision
    import json
    
    os.environ['GOOGLE_APPLICATION_CREDENTIALS'] = './GoogleVisionKeys.json'        # Autentykacja klienta
    client = vision.ImageAnnotatorClient()

    with io.open(path, 'rb') as image_file:
        content = image_file.read()

    image = vision.Image(content=content)

    response = client.text_detection(image=image)
    texts = response.text_annotations
    
    print(float(texts[0].description))

    if response.error.message:
        raise Exception('{}\nFor more info on error messages, check: ' 'https://cloud.google.com/apis/design/errors'.format(response.error.message))
    
    return float(texts[0].description)
        
detect_text('meter_digits_only.png')			# obrazek do detekcji cyferek