Milestone LPR 1.0 - Manual (Page 17)

Milestone XProtect
®
LPR 1.0 Administrator's Manual
www.milestonesys.com 17 LPR servers, sources and lists
Character Height tab
Here you define the minimum and maximum height of the license plate characters (in percent).
These character settings influence the recognition process as they partly determine the recognition
time. As a rule, the larger the difference between the minimum and the maximum character size:
1. the more complex the LPR process is
2. the higher the CPU load is
3. the longer you have to wait for the results.
You see a shaded area in the test image (see "Select image for test" on page 15) containing ABC 123.
Since this shaded area grows/shrinks proportionally with the current character setting in the min/max
character setting fields to the right, you can use this shaded area to drag the text on top of the license
plate in the captured image, to compare license plate characters in the image.

Minimum character height: Use the arrows to set the minimum hight of characters to be
included for LPR. Any license plates containing characters below this threshold is not included
in LPR.

Maximum character height: Use the arrows to set the maximum hight of characters to be
included for LPR. Any license plates containing characters above this threshold is not included
in LPR.
Reading Direction tab
Here you specify reading direction for the shaded area containing ABC 123 and color inversion for the
test image. The text in the shaded area must follow the direction of the test image, for the recognition
to function correctly.

Do not rotate: Shaded area stays as it is.

Rotate 90 degrees: Shaded area rotates 90° to the right.

Rotate 180 degrees: Shaded area rotates 180° to the right.

Rotate 270 degrees: Shaded area rotates 270° to the right.

Flip: Shaded area is mirrored.

Invert: Colors of the test image is inverted.
Processing tab
Basically, the recognition process can be divided into two major steps: finding the plate(s) and
recognizing the characters on the plates. However, the items on the Processing tab allow a user to
define a trade-off between processing speed and recognition quality.
The general rule states that high recognition quality:

needs the highest computational effort

results in higher CPU load

requires more time to return an answer.