2MP v/s 8MP if resolution is configured for 1920x1080

[kdsteele]

If you had a IPC-HDW3241T-ZAS 2MP which has a native resolution of 1920x1080 and a IPC-HDW3841T-ZAS 8MP and manually configured the latter to 1920x1080 resolution, would there be any appreciable difference in image quality? Both models feature a 1/2.8 CMOS image sensor.

 

[wittaj]

Reducing the resolution from 8MP to something less does't reduce the pixels of the screen on the sensor - the pixel count stays the same in the camera as that is a fixed "pixel screen", so the only thing you are reducing is the amount of storage space needed by dropping the resolution.

At night, the image quality of the 2MP will usually beat the 8MP that are both on the same sensor size as the 8MP needs 4 times the light of the 2MP and downrezing the 8MP to 2MP doesn't defy the law of physics...

 

[kdsteele]

Thanks - but I'm not clear on this. 1920 x 1080 = 2,073,600 (roughly 2 million) which explains why the camera is referred to as 2MP. When I configure a 8MP camera to output 1920 x 1080 is it effectively not using 6 million pixels? If so, wouldn't the image quality be about the same as a 2MP? (except for the lighting issue you mentioned)

 

[IAmATeaf]

The camera will down sample the 4K image down to 1080p so the result would depend on the quality of the engine or code used to produce the final image.

Much like a 4K TV doing the reverse and up sampling say a 1080p image to 4K, the end result varies between TV with Sonys engine for doing this regarded as amongst the best.

So wether it would be the same, better or worse will entirely depend on the cam.

 

[Bitslizer]

It depends on the camera. Fancy one can do pixel binning. Ie combine 4 pixels into 1 simulated big pixel. But I'm not aware of any CCTV camera that do this

 

[wittaj]

It is still using the 6 million pixels - the camera doesn't change the "pixel resolution screen" on the camera when you go from 8MP to 2MP. The sensor still needs 4 times the light going from 8MP to 2MP, so the native 2MP camera will result in a better image at night. The firmware will make some attempt at downrezing it, but it could be a complete crap image or a usable image, but if there is a concern that the 8MP isn't performing or wouldn't perform well at night, then it is better to go with the 8MP.

I have a 4MP and 2MP on the same 1/2.8" sensor and the picture quality is quite different between the two and the 2MP kicks it's butt. The difference between 8MP and 2MP is even greater.

In most instances, you want to get a camera that will perform at your location for the worse situation, which for most of us is at night when it is dark and there is little to no light. If a camera performs at night, it is easier to tweak settings to make it work during the day than it is the other way around.

My 2MP cameras outperform my neighbors 4K (8MP) cameras....why....because they are both on the same size sensor.

When we had a thief come thru here and get into a lot of cars, the police couldn't use one video or photo from anyone's system but mine. Not even my other neighbors $1,300 8MP system provided useful info - the cams just didn't cut it at night.

My neighbor tried the "I will just downrez the 8MP to 2MP" and the image was a soft dark mess.

His system wasn't even a year old and after that event has started replacing with cameras purchased from Andy here based on my recommendation and seeing my results. He is still shocked a 2MP camera performs better than his 4k cameras and he cannot figure out why downrezing from 8MP to 2MP doesn't work properly... It is all about the amount of light needed and getting the right camera for the right location.

It is simple LOL do not chase MP - do not buy a 4MP camera that is anything other than a 1/1.8" sensor. Do not buy a 2MP camera that is anything other than a 1/2.8" sensor. Do not buy a 4K (8MP) camera on anything smaller than a 1/1.2" sensor. Unfortunately, most 4k cams are on the same sensor as a 2MP and thus the 2MP will kick its butt all night long as the 4k will need 4 times the light than the 2MP... 4k will do very poor at night unless you have stadium quality lighting (well a lot of lighting LOL).

 

[bigredfish]

^^^^^
THIS

I’m quite sure there are better more complex technology details, but bottom line, no, downscaling your 8MP cam to 2MP won’t provide a better image.

 

[The Automation Guy]

You have to understand that you have capture resolution and playback resolution. Even if your playback resolution is low, the system is capturing/recording all the pixels. This is important when it comes time to export the footage when you need to use it for identification purposes.

In high light environments, a 8mp camera will be better than a lower resolution camera (if all other things are equal). This is because there will be more pixels per inch available for identification purposes. Now that being said, that 8mp camera takes 16 times the amount of light to produce the same image as that 2mp camera, so in low light environments the lower resolution camera will perform better (if all other things are equal).

You have to decide which camera fits your goals and your environment. If you have an environment where you have plenty of light all the time, a high resolution camera with a properly spec'd sensor size is probably better. If you have an environment where the light will vary and be low at times, then a camera with a large sensor and lower resolution is going to out perform high resolution options.

Then you have plenty of differences in image quality between brands even if the resolution and sensor size are comparable. This makes choosing cameras pretty hard. The best way is to buy a recommended camera and test it in your environment to see if it will work (this is when using something like Amazon with free returns can be very helpful) before you buy a bunch of cameras. There is no "one size fits all" camera out there and you have to find what is going to work well for your situation unfortunately.