Troubleshooting outdoor exposure issues for the SharpZ3 ALPR camera - SharpZ3 | SharpOS 13.1

SharpZ3 Administrator Guide 13.1

series
SharpZ3 | SharpOS 13.1
revised_modified
2020-07-14

You can resolve exposure adjustment issues that result in under-exposed or over-exposed license plate images in SharpZ3 installations.

Procedure

If ALPR images (or some specific plate models) are always too dark at night:

  1. Perform the exposure calibration at night.
  2. Increase the maximum Shutter time value until you are satisfied with the ALPR images.
  3. If you reach the maximum Shutter time level and the ALPR images are still too dark, increase the maximum Gain value.

    If ALPR images are often too dark at night:

    In this case, the exposure setting range might be too large, causing exposure to be too low. To reduce the range, start by increasing the minimum values. Because higher minimum values might lead to over-exposure for daytime reads, perform the adjustment during the day.

    In this case, the exposure setting range might be too large, causing exposure to be too low. You can reduce the range by increasing the minimum values, but you should do this carefully because increasing the minimum values can cause over-exposure during the day. Therefore, this adjustment should be done during the day.

  1. Make the adjustment under sun illumination.
  2. Increase the minimum Exposure time value as much as possible without compromising image quality.
  3. If the minimum Exposure time value reaches its maximum value, then you can increase the minimum Gain value. Test to make sure image quality is still satisfactory.

If ALPR images (or some specific plate models) are always too dark even under sunlight:

  1. Increase the maximum Exposure time level as much as possible without over-exposing the plate.
  2. If the maximum Exposure time reaches its maximum value and the plate is still under-exposed, increase the maximum Gain value one step at the time until you are satisfied with the images.

If ALPR images (or some specific plate models) are always too bright under sunlight:

  1. Make the adjustment under sun illumination.
  2. Decrease the minimum Gain value until you are satisfied with the plate images.
  3. If you reach the minimum Gain level and the ALPR images are still too bright, decrease the minimum Exposure time value.

    If ALPR images are often too bright under sunlight:

    In this case, the Exposure time range might be too large, causing exposure to be too high. You can reduce the range by decreasing the maximum values, but you should do this carefully because decreasing the maximum values can cause under-exposure at night. Therefore, this adjustment should be done during the night.

  1. Make the adjustment at night.
  2. Decrease the maximum Gain value as much as possible without compromising image quality.
  3. If the maximum Gain value reaches its minimum value, then you can decrease the maximum Exposure time value. Test to make sure image quality is still satisfactory.
  4. If you reach the minimum Exposure time level and you are still not satisfied with the image quality, perform the complete day and night exposure adjustment again.