The results of reading plates depend essentially on the quality of the images that are submitted to the reading engine.
One of the first things the operator performing the image acquisition should pay attention to is the size of the plate characters on the image. These characters should have on the image a size around 25 pixels. Consequently, if during its first rounds, when the plate is very clear on a good quality image, the engine produced aberrant readings, it is doubtless that the plate is too small (taken from too far), or too close (taken too close). This of course depends on the device used and it is a distance that will have to be determined experimentally. On a plate taken too close, the engine risks reading the references of the establishment which placed the plate (they often appear under the characters of a plate), taken too far the engine will not produce a response, or else incomplete.
Another important parameter is the tilt parameter:
• A side shot will overwrite characters on one side of the image:

• A top shot will overwrite the characters vertically

It is therefore advisable to take the shots facing the plate, and holding the camera as much as possible at the height of the plate, and this is all the more true as the resolution of the camera where the car park lighting requires taking the plates fairly close.
Finally, but this is true for all photos, you must move as little as possible when shooting, especially with a camera with a slow shutter speed, in order to avoid the effect of “shake”, which produces a blurred image of the plate.