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Tips & Conclusion
Additional Tips to Improve LPR
While there’s plenty that you should do, there’s also plenty that you should not do. Let’s face it. Cameras come with a lot of settings, and it’s easy to switch on a bunch of settings that you either don’t know what they are or don’t need and forget that you’ve activated. Here are some to keep in mind:
Automatic gain control (AGC), digital noise reduction (DNR), autofocus, and backlight compensation (BLC) are all features you want to keep disabled while enabling LPR camera setup. Once again, this is because it will give you the best chance of grabbing that license plate number from a moving vehicle using LPR .
AGC creates issues because the gain itself prompts digital noise and lower recognition in the image. It’s often much simpler just to leave the feature off. DNR is best left alone because it is performed by removing pixels based on comparing two frames. Although this might seem harmless, it’s often not because it can easily remove pixels that could be helpful to you in the future. Next, you can pass on autofocus because adjusting the sharpness often reduces the recognition quality in the image itself. Finally, the BLC can cause issues with the image because it often occurs when a light source enters a frame. When the pixels do not have enough time to properly adjust, the camera will not be able to capture a good image.
And, while this may seem obvious, we see that the best LPR contains images that are in landscape rather than in portrait view. This makes intuitive sense since the license plate itself is often oriented in the landscape than portrait mode. And, just like watching TV, we (and thus our LPR engine) are used to seeing the world in a landscape format.
Following the best practices discussed in this article can be the difference between an LPR accuracy of 55 percent and 99.5 percent. In many cases, it’s just as much about knowing what to do as it is knowing what not to do. Start with camera height, width, and distance and you’ll be able to start updating your LPR camera setup, so your images are usable and accurate for safety and surveillance purposes.