GeoVision LPR User Manual

GV-LPR

Qualified Image Criteria

© 2010 GeoVision, Inc. All rights reserved.
All GeoVision Products are manufactured in Taiwan.

2010/11

English

LPR-QG-A

To increase the license plate recognition accuracy, you need to install the LPR
camera in the proper way to capture the qualified plate images. When you
install the LPR camera, there are certain criteria to meet, including the plate
size, the lighting condition and the angle of the camera. In this document, we
provide the qualified image examples, and the unqualified image examples,
which are generated when the LPR camera is set in an improper way. We also
provide the easy installation instructions on how to fix those unqualified plate
images.

The qualified image examples

You should capture and fill the image with a full width of vehicle. In this way,
the height of the captured plate characters would approximately fall between
30 and 35 pixels.

Day

Example

Night

Example

The unqualified image examples

The plate is the hollow-letter type:

Example

Try to:

Reduce the illumination.

The image is unclear:

Example

Try to:

Adjust the focus or the shutter speed of the camera.

The image is overexposed:

Example

Try to:

Reduce the illumination, or adjust the angle or the setup direction of the
camera.

The image is interfered by the headlight:

Example

Try to:

Use the professional LPR camera to avoid the headlight interference.