This is a very good question. I was always puzzled when seeing some IPC specs where the IRE numbers are included. How do we measure the IRE in an IPC camera?
Could the following two metrics be used to replace the IRE?
2. Gain in AGC
So even if you wanted to use IRE, you cannot.
Unless you really, really wanted to...
Camera ip out to MegaPixel composite decoder, camera set to minimal compression (MJPEG?), 30fps. Probably not what you had in mind, but would it work at all?
IPVMU Certified | 08/04/14 12:47am
Presumably in the past, camera manufacturers would simply connect the composite analog output of their cameras to a waveform monitor to check IRE levels? Assuming that to be true, I think there are a couple of options for checking IRE levels with IP and other non-composite cameras.
The first option is to use software. You could take a video clip recorded by an NVR and open it into a non linear editing (NLE) application such as Final Cut Pro or Premiere Pro. Both of these applications have waveform monitoring scopes which can show luma in IRE units. However I don't like this method for a couple of reasons:
- The first is NLE operators have complained for years about the inaccuracy of the built-in scopes in NLE software. They are only useful to provide an indicative result.
- The second is this method doesn't help with live testing because it is reporting the IRE levels of the video clips recorded from the IP cameras. If I was a camera manufacturer wanting to adjust IRE levels, I would want some way of doing this live.
The second option is to use a hardware waveform monitor which was traditionally very expensive with scopes costing over US$10000. Forgive me if the following reads like an advertisement for Blackmagic Design but I'm intimately familiar with their products. I previously worked at Blackmagic Design where they created their UltraScope and SmartScope Duo products for US$495 to $995. These products include waveform monitoring of standard television signals in SD and HD. Quoting from the UltraScope marketing material, "Composite video is synthesized from the SDI input displayed for a better view for aligning decks and other video equipment. Even though UltraScope is fully digital, the synthesized composite waveform makes it easier for editors who are familiar with composite waveform monitors." Blackmagic Design also has their UltraScope Duo 4K product which includes composite waveform monitoring of SD, HD and Ultra HD 4K television signals for US$995. The waveform monitor on all four products can use IRE units and I think this method may have potential for the purpose you have described.
The only trick will be how to get the live video from the IP camera into the SDI port of the UltraScope or SmartScope Duo. I think some IP cameras have an HDMI output which could be adapted using a US$295 Blackmagic Mini Converter HDMI to SDI 4K. If the camera had no video output, one could set the desired IP camera to display full screen on the VMS workstation or NVR. Then adapt the HDMI or DVI output, of the graphics card, to SDI by using a converter such as US$395 Blackmagic DVI Extender or the Mini Converter HDMI to SDI 4K. This would allow one to perform live waveform monitoring of the IP camera using traditional IRE units all the way from SD up to 4K.
(Why) do you think that a manufacturer's specification such as 1 lux f/1.2 50 IRE, is anymore meaningful than 1 lux?
Since neither gain or S/N is not specified (nor is it easy to specify as you point out), manufacturers can manufacture almost any number they wish. Perhaps the noise at 0 lux could be subtracted from the measurement at 1 lux to normalize the gain, but....
I understand how people 'want a number', but in this case at least, everyone would be better served by the mfr. capturing a standard tvl chart at standard distance at whatever lux they desire, and publishing the picture and the lux number, in the same spirit as you did here: Ranking IP Camera Low Light Performance. Agree?
Apparently someone didn't tell LT Security (Hik) about the demise of IRE for MP cameras:
Though they're probably just using their SD analog output scaled down. Also interesting is the claim of support for an unspecified type of H.264 SVC