can't eliminate glare on license plates/signs on Dahua IPC-HFW8232 using Blue Iris

[LeeZ]

HI Dahua IPC-HFW8232 experts,
I've been trying to eliminate the glare on license plates at night as in the attached picture on the license plate of the car closest to camera. I turned on smart IR, and I zoomed in enough so as not to include the corner of the eave of the corner of the roof that the camera is mounted under within the field of view but this does not help.



Can someone please help with how I can modify settings so that this can be eliminated, as license plate recognition was one of purposes of purchasing this camera.

Thank you,
Lee

 

[looney2ns]

HI Dahua IPC-HFW8232 experts,
I've been trying to eliminate the glare on license plates at night as in the attached picture on the license plate of the car closest to camera. I turned on smart IR, and I zoomed in enough so as not to include the corner of the eave of the corner of the roof that the camera is mounted under within the field of view but this does not help.

View attachment 32578

Can someone please help with how I can modify settings so that this can be eliminated, as license plate recognition was one of purposes of purchasing this camera.

Thank you,
Lee

Read the Lpr section of this board. Your cam for one is at too sharp an angle to plate. And you need more zoom.

 

[J Sigmo]

And realize that license plates use paint loaded with tiny glass spheres that behave as retroreflectors, sending light back towards the source of the light to make them more visible (like reflectors). In this case, because your camera seems to have built-in IR LEDs, and the camera's auto exposure is averaging the brightness of the entire scene, the license plate is far brighter in the scene than the average. So the license plate and other reflectors end up, as photographers would say, "Blown Out" (grossly over exposed) in order to get reasonable exposure over most of the scene.

http://www.virginiadot.org/business/resources/materials/mcs_study_guides/bu-mat-pavemarkch2.pdf

If you don't mind making everything else in the scene appear very dark, you may be able make a manual adjustment to the exposure for that camera, optimizing the exposure for the highly-reflective license plates. You'd then want a separate camera set up like you already have this one, to show the overall scene since the one adjusted for the reflective license plates would be pretty much black everywhere else.

You could make manual exposure adjustments and see what it takes to get good visibility for license plates and then see how dark that makes everything else, but I do think you'd end up needing two cameras because the dynamic range is just too great to capture it all at once.

Some digital SLRs have adjustments for their auto exposure or flash exposure that will make them very "protective of highlights". That's usually not what you want, but there are situations where it's an advantage. I doubt that there is a setting like that for your security camera, but this would be a case where it might prove handy!

 

[looney2ns]

Almost always have to dedicate a cam to LPR.