Hey guys, just wanted to say thank you to everyone here for helping me understand LPR cameras better, and for making my attempt at it even possible. I just got a Dahua Z12E, and was wondering if anyone has tried it at night with color instead of B/W? I have it aimed at an intersection roughly 230 feet away, and the B/W settings are just past their limits (anything closer is fine). Since I can reach this distance during the day just fine, I switched over to color last night to try it out. My street has plenty of lights, so thought it might work. The auto settings are readable on parked cars, but not cars in motion, which I already knew would be the case from y'all. I tried messing around with the manual settings a bit, but just seemed to make it worse. I remember someone else stating it would be nice to have color night pictures for either this or the Z4E, but could not find if they ever tried it out. Anyway, I was just wondering if anyone had dialed this in at some point, or had some suggestions for me to try.
Color Night Settings for Dahua Z12E
- Thread starter Madhatter2k
- Start date
The same techniques apply - you need a fast shutter. If you can't get it with infrared at 230 feet I doubt you have enough light for color and motion.
The reason infrared works is because we need fast shutters to capture freeze frame and we are taking advantage of the reflective properties of the plate with the blast of infrared. If you slow the shutter too much with infrared then the plate is all white.
So once you try a 1/1000 or 1/2000 shutter to capture moving plates, you probably don't have enough light for a color image.
Most of us don't have enough light to get color motion of plates. The few that do have lighted streets and capturing at a stop sign so they can slow the shutter to 1/250 or 1/500.
The reason infrared works is because we need fast shutters to capture freeze frame and we are taking advantage of the reflective properties of the plate with the blast of infrared. If you slow the shutter too much with infrared then the plate is all white.
So once you try a 1/1000 or 1/2000 shutter to capture moving plates, you probably don't have enough light for a color image.
Most of us don't have enough light to get color motion of plates. The few that do have lighted streets and capturing at a stop sign so they can slow the shutter to 1/250 or 1/500.
Yeah, I noticed 1/1000 and 1/2000 didn't work well at all, so I tried slower settings. i think I left it on 1/250 overnight, but they will probably be streaky. I will check the results when I get home. What about setting it to 1/1000 (or maybe 1/750 through custom settings), but cranking the gain and/or the iris up much further than if you were working with B/W?
The problem is cranking gain and iris will introduce ghosting and artifacts.
Maybe you will surprise us, but I think if you can't get it with infrared then color is out of the question.
Believe me we would all prefer to capture color and in many instances just for observations and not plates people don't have enough light to run in color.
LPR adds another wrinkle in that you have to run. Even faster shutters and faster shutters mean more light is needed.
I hate to burst the bubble, but if you can't get plates with IR, I think in color is out of the question. You would need to add supplemental IR like an axton unit.
Or get the camera closer. 230 feet is stretching the limits without additional light.
Maybe you will surprise us, but I think if you can't get it with infrared then color is out of the question.
Believe me we would all prefer to capture color and in many instances just for observations and not plates people don't have enough light to run in color.
LPR adds another wrinkle in that you have to run. Even faster shutters and faster shutters mean more light is needed.
I hate to burst the bubble, but if you can't get plates with IR, I think in color is out of the question. You would need to add supplemental IR like an axton unit.
Or get the camera closer. 230 feet is stretching the limits without additional light.
Thanks wittaj for your reply, and for confirming that the normal rules still apply in this situation.
I just checked out the videos from last night, and none of the plates are visible at 230 feet as expected, but were fine closer up (about 100 feet). I had the shutter set to 0 ~ 3, gain 50 - 70, and HLC at 100. I can actually clearly see the plate (it is visible, but can't make out the numbers). I will change my settings tonight, and try again.
Quick Question if you don't mind. When you set the shutter to "1/1000" it is constant, but what happens when you set a custom range (Example: 1 ~ 2 ms). Does it choose the average speed (ie 1.5 ms), or does it logically choose the best speed within that range?
I just checked out the videos from last night, and none of the plates are visible at 230 feet as expected, but were fine closer up (about 100 feet). I had the shutter set to 0 ~ 3, gain 50 - 70, and HLC at 100. I can actually clearly see the plate (it is visible, but can't make out the numbers). I will change my settings tonight, and try again.
Quick Question if you don't mind. When you set the shutter to "1/1000" it is constant, but what happens when you set a custom range (Example: 1 ~ 2 ms). Does it choose the average speed (ie 1.5 ms), or does it logically choose the best speed within that range?
It would be nice if it were that simple LOL.
For LPR it is best to have a constant shutter. HLC at 100 can also cause issues. Try 50
What happens with a range is that if the sensor sees more light, the shutter goes faster and less light, the shutter goes slower.
With a range, the camera is going to tend to go with what will give it the brightest image, which means slower shutter and cranking gain and other range parameters higher.
For plates where the image is black except for the headlight and plates, that shutter adjusting to the headlights could be the difference between getting a plate or not. The car just isn't in the field of view long enough so the shutter and all the parameters are adjusting to try to get a bright image based on the parameters given to it. And that is how plates are missed.
Here is a representative sample of plates I get at night of vehicles traveling about 45MPH at 175 feet from my Z12E at 1/2000 shutter. I have no street lights or neighbor lights. Just my house and the infrared from the camera.
For LPR it is best to have a constant shutter. HLC at 100 can also cause issues. Try 50
What happens with a range is that if the sensor sees more light, the shutter goes faster and less light, the shutter goes slower.
With a range, the camera is going to tend to go with what will give it the brightest image, which means slower shutter and cranking gain and other range parameters higher.
For plates where the image is black except for the headlight and plates, that shutter adjusting to the headlights could be the difference between getting a plate or not. The car just isn't in the field of view long enough so the shutter and all the parameters are adjusting to try to get a bright image based on the parameters given to it. And that is how plates are missed.
Here is a representative sample of plates I get at night of vehicles traveling about 45MPH at 175 feet from my Z12E at 1/2000 shutter. I have no street lights or neighbor lights. Just my house and the infrared from the camera.
I had some luck with the color, but switched back to B/W for now. However, I can't seem to dial in the settings like I want. Unfortunately I don't have a lot of traffic to work with, and when I tried to park down the street to do it myself, it was not welcomed. Anyway, I was just wondering if you could share your order of changes. It looks like everyone starts with the shutter (1/2000 seems to work best for me), but then some people go to the Gain next, where others mess with the Iris, then to the 3D settings, and finally to the normal display settings, which are just post processed. What order do you go in?
For a Dahua 7442-Z4 (8-32mm lens) the settings that work for my use are in the attached PDF. Your settings will depend on your local lighting conditions.
Hey guys, I had a breakthrough last night right before I went to bed. I think my biggest problem was I have been fighting the bright lights on my street instead of using them. Believe it or not, I wound up actually using "aperture priority" (I think it was called). When I first set this up, I thought it looked too good, and it was going to fail like when you get parked cars perfectly, but not cars in motion. However, after messing with it for just a few passes, I got it working really well. This is obviously not going to work for those of you who are working with no street lights, but if you have them give it a try. The settings I can remember are below. Basically what I did was enable the mode, set the Iris number low, and matched the Exposure Compensation setting. Then I turned HLC to 100, since headlights are harder in this mode (note: LCD are fine, but Halogen are bad), and then tweaked the Illumination settings until the license plates had no reflections. Once I actually dial in my settings, I will post my final findings, and some pictures. All of my results were from 150 - 300 feet looking down my road (not across). For me, it is basically like having night vision mode, but without the streaks and overwhelming headlight glare. The best part is you can tell what make/model the car is instead of just getting the license plate.
Iris: 25
Exposure Comp: 25
HLC: 100
Illumination Near: 0
Illumination Far: 25
Iris: 25
Exposure Comp: 25
HLC: 100
Illumination Near: 0
Illumination Far: 25
Thanks for your reply. It is always good to hear what others are having luck with. However, I found a different method that seems to work well. I am hoping to dial that in, and be able to get the results you are having in pitch black with my street light setup. I posted my first attempt. See what you think.
Please post pics to show results.
Flintstone61
Known around here
You can make a range of Shutter speed if you want. Esp. if you use just a DAY or NIGHT setting in the Camera webUI. If you choose both you might want to make a range of Gain.....for twilight, sunset and NIGHT and daybreak lighting changes.
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Flintstone61
Known around here
On the Condo z12e, I went straight B&W 24/7 IR on all the time. no fairy dust, no focus fuckeroo, no finetuning shit...just plates. 24/7...ONE JOB.
everytime you try to extend a camera into a second function you have compromises.
everytime you try to extend a camera into a second function you have compromises.
Flintstone61
Known around here
I am considering going full time B/W with mine.
Mike A.
Known around here
- May 6, 2017
- 4,199
- 7,066
You almost sound like you know what you’re doing now. It’s kinda scary.
Flintstone61
Known around here
Focus Fuckeroo: The bad guys come in the lot at 2:00 AM and camera night focus has gone out of tune, because your set to run DAY color/Night B&W. And now you can forget your call to the Sheriff because you lack evidence worthy of creating a Case#.
@Mike A. Yeah, I didn't know what I was doing, but With somewhat regular events, The weakness in your Cam game is pointed out to you by the criminals/residents everytime you have an event that you can't get corroborative evidence.
They made me look stupid....This pissed me off, So I came in after work and tuned the LPR cam to the choke point in the parking lot and was getting 99.9% of plates. And tuned the back parking lot cams seasonally to see as many plates as possible. While having overview cams to get the big picture.
@Mike A. Yeah, I didn't know what I was doing, but With somewhat regular events, The weakness in your Cam game is pointed out to you by the criminals/residents everytime you have an event that you can't get corroborative evidence.
They made me look stupid....This pissed me off, So I came in after work and tuned the LPR cam to the choke point in the parking lot and was getting 99.9% of plates. And tuned the back parking lot cams seasonally to see as many plates as possible. While having overview cams to get the big picture.
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Hey guys, sorry for the late response, and yes I come with pictures. The settings I am finally set on are below. This seems to work great, except for 1 fatal flaw. If a car has LED or HID headlights it is fine, but if they have Halogen it blows out the image (image below). If they come closer to my house, I can still get them, but if they turn on the road to the left (approximately 250 feet), there is no chance. I included an image during the day, one at night, and one with Halogen headlights for reference.
@Flintstone61: Yes, I knew about the Gain range, but thanks for the suggestion. I tried setting my camera like everyone else, but could not hone in on a good setting to keep it at. I think my best results before were at 1/2000 Shutter and 20 – 60 for Gain with a few other settings tweaked. I think my biggest problem is my circumstances are different than most of you. I am looking down a road (with 250 feet between the foreground and the background) instead of across a road at a fixed distance. I also have street lights, so cars alternate between very dark and vary light settings constantly. I have luckily not had any issues with the day/night switch. I have been using the “DahuaSunriseSunset” tool, and it is working great. However, I do agree with you about compromises. Mine is I get everything, except for cars with Halogen headlights.
Current Settings:
Mode – Aperture Priority
Iris – 25
Exposure Comp – 0
HLC – 100
Near Light – 30
Far Light – 100
If anyone tries this later down the road, you first need to decrease the Iris as far down as you can. Along the way, you will notice it drastically decreases your clarity. I hit this point at 20, and increased it back to 25. Then I matched the Exposure (to start with), and then dropped it until I liked the overall scene. The rest of the settings are pretty obvious, but if anyone needs more explanation, I can tell you what I ran into. If you know of anyone who has this setup, please send them my way. I would be very interested in what they have done.
@Flintstone61: Yes, I knew about the Gain range, but thanks for the suggestion. I tried setting my camera like everyone else, but could not hone in on a good setting to keep it at. I think my best results before were at 1/2000 Shutter and 20 – 60 for Gain with a few other settings tweaked. I think my biggest problem is my circumstances are different than most of you. I am looking down a road (with 250 feet between the foreground and the background) instead of across a road at a fixed distance. I also have street lights, so cars alternate between very dark and vary light settings constantly. I have luckily not had any issues with the day/night switch. I have been using the “DahuaSunriseSunset” tool, and it is working great. However, I do agree with you about compromises. Mine is I get everything, except for cars with Halogen headlights.
Current Settings:
Mode – Aperture Priority
Iris – 25
Exposure Comp – 0
HLC – 100
Near Light – 30
Far Light – 100
If anyone tries this later down the road, you first need to decrease the Iris as far down as you can. Along the way, you will notice it drastically decreases your clarity. I hit this point at 20, and increased it back to 25. Then I matched the Exposure (to start with), and then dropped it until I liked the overall scene. The rest of the settings are pretty obvious, but if anyone needs more explanation, I can tell you what I ran into. If you know of anyone who has this setup, please send them my way. I would be very interested in what they have done.
