Unwanted camera features

When you configure cameras for LPR, note the following:

Automatic gain adjustment: One of the most common types of image interference caused by cameras is gain noise.

Automatic enhancement: Some cameras use contour, edge or contrast enhancement algorithms to make images look better to the human eye. Such algorithms can interfere with the algorithms used in the LPR process. Milestone recommends that you disable the cameras’ contour, edge and contrast enhancement algorithms whenever possible.

Automatic compression: High compression rates can have a negative influence on the quality of license plate images. When a high compression rate is used, more resolution is required in order to achieve optimal LPR performance. If a low JPEG compression is used, the negative impact on LPR is very low, as long as the images are saved with a JPEG quality level of 80% or above, and images have normal resolution, contrast and focus as well as a low noise level.

License plate image saved with a JPEG quality level of 80% (i.e. low compression); acceptable.

License plate image saved with a JPEG quality level of 50% (i.e. high compression); unacceptable.

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