IP MEGAPIXEL RESOLUTION…… What???
The CCTV market has mostly shifted to IP cameras. The Network camera offerings were pretty lame years ago. Expensive, complicated and poor performance in low light. Well, most of that has changed. The price is down, resolution is up and the low light performance has gotten better. So what does all this mean when it comes to picking an IP camera? Lets get an understanding of IP camera resolution and aspect ratio. They go hand in hand.
Resolution – the number of pixels that the image contains and is expressed in a horizontal quantity and a vertical quantity. i.e. 640×480 is an image that is 640 pixels wide and 480 pixels high. A pixel is an individual dot with a color value and brightness controlled by the system.
Aspect ratio – this is the shape of the image or the ratio of the quantity of horizontal pixels to the quantity of vertical pixels. The US TV standard for many years was exclusively 4 to 3 aspect ratio (expressed as 4:3). This image is therefore 4 units wide by 3 units high. Take a VGA resolution image: 640×480. If you divide the 640 by 4 you get 160. Multiply 160 by 3 and you get 480 thus you can see with some simple math that this is an image with a 4:3 aspect ratio. Now for some dumb reason, in the past few years, there has been a big shift to the 16:9 ratio. This format is widely used for cinematic theater. Great for movies, not so much for security in my opinion.
Now lets go over common resolutions and aspect ratios for security cameras.
VGA (Video Graphics Array)
VGA resolution comes from an older computer display format and generally means a camera with an image that is 640 pixels wide by 480 pixels high. VGA by today’s standards is a low resolution image. Fine for a back door camera where you can get a big close-up of the person entering. Not sufficient for detailed viewing of larger areas. VGA cameras have all but disappeared.
1280×1024. This is a resolution widely used for IP cameras a couple of years ago and is now fading for higher resolutions. Most cameras of this type allow you to choose between a 4:3 aspect ratio and a 16:9 ratio in the settings. The 16:9 ratio has a pixel layout of 1280×720 and is also called 720P high definition. If you multiply the two numbers, you will get 1,310,720 total pixels (thus 1.3 megapixel or 1.3MP resolution). You can usually get away with using a quality CCTV lens made for standard analog video on your 1.3MP camera without degrading the image. Don’t use an off-brand junk lens though. Stick with a Tamron, Fujinon, or Computar brand and you will be safe.
“Full HD”, 1080P or “High Definition”, is considered to be 1920×1080 pixels (16:9 ratio) in size and has been adopted hook, line and sinker for consumer HD TV for several years now. This resolution is still widely used for a majority of cameras as of this writing. You have heard the term 1080 or 1080P? This is where it comes from (not to be confused with 720P, 1280×720, which is not “full HD” – about half the number of pixels). Just about all 2MP cameras can output a smaller size image like those from a 1.3MP camera. But why? Bigger is more fun. You paid for those pixels, why not use em! Just kidding. Outputting a smaller size image may be advantageous if the shape of the scene you are capturing is better suited with the 4:3 ratio. Thus, less date traffic is put on the network and storage devices. NOTE: Don’t use a standard lens on your 2MP and 3MP cameras. Use a lens that has sharper optics made for megapixel cameras. You will be wasting your money if you don’t.
3MP (2048×1536) is a pure 4:3 ratio and has 1/3 more pixels capturing the video than the high definition format. Wow! I have been joking about “more is better”, but that can also get you into trouble. First is bandwidth (simply put is the amount of data that can flow through a network system without bogging down). A 3MP image frame is about twice as large as that from a 1.3MP camera. That uses up your storage space twice as fast and eats into your available bandwidth and processor power quickly. 3MP cameras are beginning to fade. Get a 3MP lens if you want a box camera, no exceptions.
Now we are talking! Twice the pixel count as full HD – 2592×1520 size. As of today, I really think this is the sweet spot. Plenty of pixels for even demanding applications, a reasonable price compared to 4K and a file size that is manageable with most NVRs. My favorite camera as of this writing is the Samsung QNO-7080R. Sharp as a tack and decent low light capability. Still the 16:9 format. If you have the network and NVR capacity. Go with a 4MP and don’t look back. You will be glad you did.
Coming in a roughly 12 megapixels – 4072×3046, this is the highest resolution we have currently available to the everyday security industry. A couple notes of caution: First, the price is up there. Between one and two thousand dollars for a fixed format camera. Yes, the price will come down. Be cautious when pairing 4K cameras with an NVR. Only a few NVRs have the horsepower to be able to handle the recording bandwidth needed for 4K. Read the fine print as other NVRs will limit the recording resolution or the frame rate severely to handle a 4K image size. Currently, the best options for 4K are the XRN series from Samsung or an appropriately equipped Exacqvision system (or similar from ONSSI, Milestone etc.). Now from the practical viewpoint: we compared a 4K camera to a high quality 4 megapixel camera. The difference was somewhat noticeable, but not major. My recommendation is to stick to a good 4 megapixel camera until the price of 4K comes down. But, it’s your money….
I am often asked what size monitor to get with my IP based CCTV system. As you probably gathered, I’m not a big fan of the 16:9 format for security. Watching movies yes. In my opinion after 30 years of doing this, most typical scenes just fit better in a 4:3 ratio frame (i.e. looking down hallways, looking down the outside of a buildings, doorways, parking lots etc). There are lots of 1920×1080 monitors on the market. If you put a 1.3MP image on that monitor, expanding the image to fit will yield about a 30% smaller viewed image than the real estate that is available for you to use. If you set your viewer to fit the horizontal pixel space of the monitor, you will have to scroll to see the top/bottom of the image. Not a deal breaker but awkward nonetheless. I like the 1920×1200 monitors. This is a nice compromise for security use between the 4:3 and the 16:9 ratios. I have several and love them. Generally by the math, 2MP and 4MP cameras fit better on a 16:9 ratio screen and 1.3MP and 3MP cameras fit better on a 4:3 ratio screen if you use the full resolution output. As I said, the 1920×1200 is a nice in-between.
Hope you like my explanation of resolution and aspect ratio with respect to security applications. Please come visit us at Pro Security Warehouse