There's actually a pretty simple explanation behind it.
Last month, around Valentine’s Day, a North Korean named Kim Jong-nam, believed to be the half-brother of North Korean dictator Kim Jong-un, was assassinated at KLIA2.
Less than a week later, Japanese broadcaster Fuji TV released a grainy CCTV footage showing a woman covering the victim’s face with something from behind before she hurriedly left the scene. Within a short timeframe, the perpetrator was identified and then detained with much praise to the local authorities.
Now, this begs the question: why are CCTV footages always so grainy and in low quality?
With the advancement in mobile camera technology - dual lens, optical zoom, 41 megapixels - can't we just replace CCTV cameras with mobile phones?
Though many question the poor quality of security footage in an age of 4K video cameras, we must first address the most important misconception that mobile cameras are better than CCTV cameras.
Sure, colours and vividness of images from our smartphones are pretty but within the context of surveillance, prettiness isn’t at the highest of the list of important factors.
Here are four main reasons why we will never replace common CCTV cameras with smartphone cameras:
CCTV CAMERA SENSORS ARE SOPHISTICATED
You might’ve seen them in shopping malls, banks and cinemas; CCTV cameras with cute LEDs round the lens. Surveillance cams lately are equipped with infrared (IR) illuminators designed to capture video in low or no light environments. Powered by banks or arrays of IR LEDs, the environment is flooded with IR light (invisible to the naked eye) and details are then picked up by special sensors within the camera unit.
CCTV CAMERAS HAVE A WAY MORE POWERFUL OPTICAL ZOOM
Depending on the complexity and price , many modern CCTV cameras have very powerful optical zoom. Traditionally, smartphone cameras only have one prime lens (iPhones have two) where users will need to believe digital zoom to urge the image they need . With digital zoom, pictures get noisy and grainy.
IT REQUIRES TONS OF MEMORY SPACE
The storage system within the CCTV is additionally very complex. With a mess of cameras feeding footage into the central system, videos from A DAY’S worth of surveillance in decent resolution can easily chew through 1TB of storage! CCTVs record and store videos and pictures on to Digital Video Recorders (DVRs). Meanwhile, we’re deleting our pictures to form space on our smartphones to snap your OOTD pictures.
SMARTPHONES DON'T HAVE THE PROCESSING POWER
With many video feeds from different cameras, computers work round the clock alongside cameras to compress videos, timestamp them and sometimes even directly feeding footage live via network connections.
So, the big reveal is this: contrary to popular belief, smartphone cameras are actually not better than CCTV cameras!
So why are we still seeing blurry CCTV footage if they’re so much better than smartphone cameras, you ask?
This is because of image/video cropping on low resolution video.
Yes, that cropping. Just like what you do on Instagram.
Cropping a neighborhood during a low resolution video like 320 X 240 with low frames per second (FPS) affects the standard of the video as you're only selecting a coffee ‘X’ number of pixels therein area.
So, once you crop a particular footage from a coffee resolution video, what you'll get may be a very noisy picture like this:
According to a piece of writing on Quora, if an institution uses a low quality CCTV camera, only 25% of the image's resolution is recorded. Add cropping into the equation and you will get a super grainy, low quality footage.
Also, there are other factors that affect a CCTV footage, like compression when the recording is fed into a DVR set to be stored.
So, just in case you TL;DR, CCTV footages aren't bad quality in nature, it only happens once you want to crop a particular area out of the footage.
Oh, and just in case you're wondering: noise may be a sort of visual distortion produced either by low light, pixel density, exposure and sensor size. Blur, on the opposite hand, happens when the sample video is recorded in low FPS and still image is captured from a frozen image frame.
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