Haystack uses the world's most reliable OCR algorithm to read the text on the paper business cards you scan. When taking a good photo, we expect the scan to capture the text on that card about 98-99% accurately.
If you consistently get lower results, here are some tips & tricks that can help you get better results:
Make sure the text on the card is clear and not blurry (if you can't read it, the OCR can't read it either)
Make sure there is no reflection on the card itself - if you see a reflection, consider taking the photo in a bit of an angle, so the reflection is not on the card
Try to avoid shadows across the card - if you see the phone's shadow over the card, consider taking the photo in a bit of an angle so the shadow does not go over the card
Note: If you hold the camera and the card text is blurry, pull the phone away from the card until the point the text becomes clear - don't worry if the card is further away from the camera - modern phones have great resolution, so the distance should not impact the scanning results.