Fix Overexposed License Plates at Night on Viewtron LPR Cameras

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  • How do I fix overexposed / washed-out license plates at night on a Viewtron LPR-IP7 or LPR-IP4 connected to a Viewtron NVR?

    If night captures look too bright and the plate letters are hard to read, check mounting first, then lower night brightness, enable Plate Exposure, shorten Max Shutter, and zoom so the plate fills enough of the frame. These steps apply to the Viewtron LPR-IP7 and Viewtron LPR-IP4 when they are connected to a Viewtron NVR.

    Night LPR capture showing an overexposed / washed-out license plate

    Mounting comes first

    NOTE: Mounting and camera position matter a lot for LPR. Before you change image settings, confirm the camera follows the mounting guidelines for your model:

    If the camera is already mounted correctly, work through the NVR settings below in order.

    1. Lower night brightness (Image Settings)

    On the Viewtron NVR:

    1. Go to Start > Settings > Image Settings (under Camera).
    2. Select the LPR camera.
    3. Click Advanced.
    4. Set Config File to Night (use the Night & Day config as shown).
    5. Set Brightness to 3. If it is already 3, try 1 or 2.
    Viewtron NVR Image Settings Advanced night brightness set to 3 for an LPR camera

    2. Enable Plate Exposure (LPR settings)

    If night plates are still washed out:

    1. Go to Start > Settings > LPR (under AI / Event).
    2. Check the box next to Plate Exposure.
    3. Set Plate Exposure to 8. If needed, work back toward 6.
    Viewtron NVR LPR settings with Plate Exposure enabled and set to 8

    3. Shorten Max Shutter at night

    Next, tighten the night shutter:

    1. Go to Start > Settings > Image Settings (under Camera).
    2. Select the LPR camera.
    3. Click Advanced.
    4. Set Config File to Night.
    5. Set Max Shutter to 1/750. If plates are still overexposed, try 1/1000.
    Viewtron NVR Image Settings Advanced night Max Shutter set between 1/750 and 1/1000

    4. Zoom so the plate fills enough of the frame

    If you are covering a wide area (wider than about two lanes), zoom the camera in. Ideally the license plate should account for at least 6% of the entire video frame.

    From Live View:

    1. Click the LPR camera tile.
    2. Select the Image Adjust icon (it looks like a camera).
    Viewtron NVR live view with Image Adjust camera icon highlighted on an LPR camera

    Then open the Lens Control tab and hold Zoom + to optically zoom in.

    Viewtron NVR Lens Control tab with Zoom plus button for optical zoom on an LPR camera

    Quick checklist

    • Confirm LPR-IP7 / LPR-IP4 mounting before changing settings.
    • Image Settings > Advanced > Night > Brightness = 3 (or 1–2).
    • AI / Event > LPR > Plate Exposure on, start at 8 (try down to 6).
    • Image Settings > Advanced > Night > Max Shutter = 1/750 (try 1/1000).
    • Zoom so the plate is at least ~6% of the frame (Live View > Image Adjust > Lens Control > Zoom +).

    Related

    Questions on a live Viewtron LPR install? Email support@viewtron.com or call / text 1-561-433-8488.