CCTV camera settings: this is the way to get the best picture

2021-11-25 09:44:48 By : Mr. ben huang

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Those who are willing to work hard for "Wow" can read content that can have a significant impact on their CCTV clarity in the next few minutes.

As we all know, your image needs enough pixels to get the required details. However, many installers and safety management professionals I met did not actually understand this basic concept, which still scared me.

They really mistakenly believe that buying high-definition cameras and relying on the CSI laboratory is enough! No, it won't.

If the faces you want to recognize don't have enough pixels, magic won't make them appear. Let's take a look at some real world shots from the HD cameras I tested.

The Digikin target on the left is 550 pixels high. Zoom out the lens so that the digital gold in the center is only 285 pixels high (about half of the original size).

guess what? Only half of the small details can be resolved. It really is that simple.

The image on the right is a small enlarged image, so you can compare its limitations. The same camera, the same day, the same zoom lens, but the important thing is that the Photoshop fraud we have seen from so many CCTV advertisers does not exist.

If you want to know how to design correctly, check out the previous article "CCTV Guide-Setting Your Goals and Requirements".

Okay, so you have enough "target pixels" to recognize, but what if your target is moving? People often walk. Using one of the UK Home Office’s CCTV test surfaces, we can see that enough details will still be destroyed (see the picture below right).

The camera shutter of the image on the left is 1/30 second, which may apply to all cameras that are installed and retain the factory default camera settings. The picture on the right intentionally shortens the shutter to 1/125 second. See the advantage?

The factory default CCTV camera settings make us motion blur at walking speed, which destroys the identification details that all these pixels are designed to provide us. You need to set the shutter fast enough to freeze the movement.

Almost no one has set this up correctly. Be the one who does. Keep in mind that this will naturally reduce night sensitivity, so make sure that there is sufficient light.

The noise produced by the camera struggling in low light can also destroy the details maintained in good light. Therefore, never believe that the data sheet says that the camera is good at as low as 0.1 lux, because your own proper testing is the only way to discover the truth.

The night images on the left (the two immediately on the right) are not well lit, so the camera relies on its internal AGC (Automatic Gain Control) to enhance weak signals, which also increases noise.

The image on the right hand side has more light, so the camera does not need to enhance the signal, resulting in much lower noise.

The brightness of the two images is similar. Nothing has changed except the light provided. Obviously, noise will reduce the details you think can be achieved. Therefore, you should limit the AGC boost to 24dB and compensate for the lower boost with better lighting.

You will be surprised at the obvious differences between quality lenses and how this affects sharpness.

The pictures below were taken with three examples of the same camera in the same room, each using a different zoom lens from a well-known high-quality manufacturer. The difference in sharpness is surprising. Can you imagine how much sharpness is lost when using cheap lenses?

Any lens needs to be properly focused for good sharpness. How many people lose focus at night, which makes me feel frustrated all the time.

Improper installation and maintenance are to blame. The solution is simple, but this requires another article to be written another day.

Nonetheless, while many modern cameras have built-in autofocus setting tools in their software, let us take an example to consider maximizing sharpness at the widest possible distance.

Suppose your camera observes along a 50-meter-long corridor. It is equipped with a 9mm lens and F1.6 aperture on a 1/3-inch camera.

So, in order to maximize the number of focal points, do we carefully focus on more interesting objects beyond 50m? Do not. We should focus it only 4.65m away from the camera! This is the so-called hyperfocal distance.

By definition, everything farther than the hyperfocal distance is in focus, so almost all the promenades. In addition, when the depth of field of F1.6 is the shallowest in low light, objects as close as 4.25m can also be in focus.

When the iris is closed in brighter light, it will be wider. To calculate the hyperfocal length of any camera and lens, you can try this online calculator or smartphone app on the spot. The widest range of sharpness can be obtained when focusing any lens. This is direct physics.

Although IP and SDI video continue to grow, analog video is still very popular. Because there are so many Cat6 cabling in the world, baluns are still very common in transmitting analog video, but if passive baluns are used according to some manufacturer's recommendations, it may destroy the clarity.

A quick and dirty workshop inspection using an analog camera to view the test card showed the clarity outside the camera, as shown above.

Then use passive baluns on Cat6 cables, and their manufacturer recommends that they fit 400 meters on the packaging. However, after 216 meters, the high-frequency content is too weak (measure the chromaticity burst on an oscilloscope) to meet the ITU-R PAL video standard.

You can see the loss of image detail above, where the horizontal resolution drops from about 450 TVL to 400 TVL. In the entire 400m range they recommend, how severe is this loss of clarity? I dare not think, if you exceed 100m with them, you should do the same.

If you are using a cheap fake "Cat5", that is, real copper-plated aluminum (CCA), the signal will be lost too much when the distance exceeds 60 meters. Try it on your workshop bench. You will see.

The level of light at night is also easy to deceive people. We check our light meter (see picture on the right) under a street light and measure 12 lux, but this is horizontal.

This value is much higher than the lux measured on a vertical face that we are interested in seeing clearly. Instead, measure towards the camera position to get the correct design. There is only 3 lux.

Not only that, but also make sure that the light is not behind our goal. Otherwise, all this light will only create a contour without facial details, because now we are measuring only 0.3 lux with the camera on the target.

If you cannot move the light, try to counteract it by adding frontal lighting from the perspective of the camera. In the final image below, the very bright backlight in the scene is effectively offset by enough infrared rays from the lights near the camera.

I hope these ideas are useful. You may think that each of these factors will not have much impact on the clarity of the image you obtain, but if you use more than one or all of these factors, the result will be multiplied.

This is how to go from "hum" to "wow". The improvement in clarity may be very worthwhile.

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Thanks Dave! There is a brand new article in the Wasp Bucket 😉

Great article Simon, thank you.

Ha, ha, the old "I just brought a meter reader" rebuttal, challenging the challenge of wandering outside other people's homes late at night; what a poor CCTV consultant does these days is just to get the job done! Simon's very interesting article, as always, contains a lot of useful tips. Just to quickly solve a few questions you raised. You said at the beginning "people who are willing to work hard for'wow'", which usefully emphasizes one of the biggest problems we have encountered in this industry...Read more »

Simon, I want to know how many so-called CCTV system designers and installers don’t even know what you’re talking about, and there may be fewer people buying these systems. 

Of course, they can install very cheap artificial closed-circuit televisions using plug-and-play products. If only the burden of knowledge is not such a disadvantage in this industry.

Tony Stoynov Thank you for your kind words, Tony.

GuardHome Yes, I think you are absolutely correct. This is a big shame. But let us continue howling at the moon, shall we? 😉

Dr. Jon thank you for taking so much time to reply, Jon. Thank you very much, I agree with everything you say. You hit them in the head as usual. The Golden Mile is perfectly reasonable. I did not deliberately put this label on it, and for the practical reasons you explained, I almost did it in most cases. Oh, in the end, I can completely sympathize with the act of walking on the street with a light meter at night. It is essential to persuade the passing policeman that I am just a nerd lunatic!

SimonLambertConsultant Doktor Jon thanks Simon; the concept of the "golden area" is not surprisingly derived from my earlier thinking about the "golden corner", which at the time seemed to explain to some peepers that almost every aspect of camera positioning has something The simplest method of actual consequences, for good or for bad. For anyone interested in visuals, I have a somewhat cordial "golden zone" page on the Internet, which may make more sense, rather than my nonsense! – Http://www.doktorjon.co.uk/cameraangles2.html Not entirely sure that most police officers will appreciate the irony of taking light meter readings in the dark, but...Read more »

To get the best photos from CCTV, you just need to buy the perfect camera with a high-quality lens. The better your lens, the better the pixels you get when you click. By setting your camera settings in this way, you can take photos not only during the day but also at night. When using a hair dryer or soft brush to clean the CCTV lens and filter. It can even be cleaned with a silk cloth.

In fact, in most cases, the more money you spend on the camera, the better. So pixels are not that important. I mean if it has at least 5 MegaPx then it is already good. The next thing-is the quality of the lens, zoom-if it loses quality while zooming. Most of today's cameras can be controlled remotely, such as-zoom / tilt / two ways of sound-microphone and speaker. Axis is my best choice. This is an online camera live broadcast example-http://www.viralcameras.com/65/posts/5-uncategorized/8-uncategorized/24410-united-states-online-camera-lansdale-watch-cam-.html but big Most things depend on...read more »

What is the impact of increasing the horizontal viewing angle of CCTV cameras

rol0980 If you increase the horizontal viewing angle, the vertical viewing angle will increase by the same ratio. This means that the number of "target pixels" must be reduced, because the camera's sensor is now adapting to the expanded scene. As the angle increases, at some point you may find that there are too few pixels on the target to achieve the purpose of the image. Then it's time to narrow the field of vision to enough to satisfy the CCTV boss's purpose.

Does it also reduce the distance of the coverage area?

My family has just moved into a new house and I want a CCTV system. Thank you for your suggestions on how light can help provide better images and make it easier for people to recognize. I think the easiest way is to ensure adequate lighting and have a reputable company install your system. http://www.barwonsecurity.com.au/cctv

rol0980 If the viewing angle increases, the distance you need to reach the desired pixel on the target will decrease. For example, if you can achieve 250 px/m (pixels per meter) at a distance of 10m in a 20m wide scene, then widening the scene to 40m wide will reduce the 250 px/m distance to only 5m.

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I see this technology is more popular in the retail industry than anywhere else. Nowadays, retail monitoring systems are in great demand because they are helping retailers deal with many challenges. 

Hi everyone, I am using a webcam to take high-quality images in low light. The quality of the live video is very good. But when we take out a snapshot from it, some mosaics may appear on the image. Anyone suggest how to overcome this mosaic or enhance the image. The image quality is 12 MP.

My CCTV DVR has EMI problem. I know this is a DVR unit because I isolate the problem by using a power supply with an EMI filter for the camera and DRV unit, and only use a camera connected to a 10-foot RG6 coaxial cable. Can the DVR be repaired, or do I need to buy new equipment?

How to get the best resolution of 3MP and above HD cameras?

I want to know if anyone can help me solve this problem. I have installed 6 cameras for each, and I have run separate Category 5 cables with a maximum distance of 40 meters. The lines on my monitor are vertical and the picture is very poor in all directions.

This is a very informative article. Would you recommend connecting CCTV cameras to the inverter? I plan to get this http://www.ict-power.com/product/dc-ac-pure-sine-wave-power-inverters/

The problem I encountered was that my camera generated a file named *.264 on the SD card. And there are two different resolution streams, one 640×352 and one 1280×720. Each has its own independent settings. If I tell it to store the high-resolution stream on the SD card, it will not play or convert it with any utilities I have tried, resulting in a bunch of ffmpeg errors. The low resolution stream works fine. I want to know if there are some video parameter sets that I can choose to generate a viewable 1280×720 file. The options are: video format (50hz or 60hz), bit rate, ... read more »

Hello, we are an Anglo-Indian company. We are looking for 4 5 megapixel cameras for security purposes and 1 8 megapixel HD camera compatible with reading workstation screens. Please guide me with the best brand and best configuration, including one-month backup DVR/NVR, with a sufficient budget.

Hi, my name is Amaar, and I need to set the playback on H.265X to play for more than a week. How can I set it up. Please advise? Thanks in advance.

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