Image quality issue with still captures
  • Hi, I am running SS successfully monitoring vehicle movements in the road - I have iGeek IP Cameras 1080 HD streaming via WiFi. I have a fairly fast frame rate within the camera to freeze movement of vehicles that are unavoidably close to the camera. This has an impact on low light performance of the camera - that's a compromise I am happy with. My SS motion capture is set for stills only Frequency 1 and post capture 1. The stills are OK recorded to my iMac locally. However when compared with still captures directly from the same camera's software (very basic Chinese IP Camera software) sent directly to FTP on my own domain (avoiding SS completely) the SS captures are noticeably softer, a lot of the detail is lost in trees. The file sizes are slightly greater in the SS jpegs. (I can post a link to comparison images if useful)

    So my question is where can I tweak the still capture settings in SS to improve IQ? Are they dictated by the SS video settings? (currently H.264RTSP video and audio) Would I have to up the bit rate leaving the camera to give me equivalent IQ of the stills taken in SS?

    Note: I am not using audio - does the codec still compress audio as well even though there is no signal?
  • FYI these are my IP Software settings:
    Brightness, Gamma, Sharpness all at default
    WDR: = OFF
    Aemode: = AUTO
    Imgmode: = Illuminance (can't see difference between Frame Rate and Illuminance)
    IR LED Control: = ON
    Shutter: (1-10000) = 50 (default is 10000, but I deduce this is a max shutter level, 50 gives sharper, frozen stills)
    IRCut: (1-1024,the late value,the greater the switching time) = 150 stops switching too early at dusk, and prevents switching from IR to colour when headlights overexpose
    Noise: (0-100,Lower according to the work) = 0

    Video Settings:
    Video format: 50Hz
    Video Coding: highprofile (I record to a iMac)
    First stream  Resolution: 1920x1080
    Bit rate: kbps (32-8192) = 2000
    Maximum frame rate: = 8 fps (balance between sharp images and reactiveness)
    Key frame interval: (2-150) =16
    Bit rate control:  VBR
    Image quality: = 1 (best)
    Audio Off

    In Security Spy I have used:
    H.264 RTSP
    Motion Capture (masked):
    One movie per event, 8fps, PreCap 1, Post Cap 1
    Still Cap: Freq:1 Post Cap:1
  • I would normally advise VBR encoding at a high quality setting, but you already seem to have this set. With VBR, the camera should adjust its bit rate automatically to give you the visual quality specified, so it's possible that in this circumstance the bit rate control does nothing, although it could also indicate the maximum bit rate that the camera is allowed to provide. So there is a chance that increasing the bit rate setting may give you a bit more quality.

    When SecuritySpy captures a still JPEG image, it has to re-encode this from the H.264 stream, which does involve a slight loss in quality. Perhaps the other software you mention is instead receiving a JPEG stream? I'm not sure. If you can email us examples of the different images we'll take a look.
  • Hi Ben,

    I use VBR but I wonder if the instant presence of a big vehicle (from a static image previously) is just too much change in compression required for the VBR to respond.. so the VBR is still on a low compression rate when the capture occurs. I will experiment with CBR at 3000kbs and see if that improves.

    Here is the direct from camera to FTP image:
    https://duaw26jehqd4r.cloudfront.net/items/3p1Y0w3c3w2T1m2O2A01/iGeek to FTP A18123009010011.jpg?v=4f7ec621

    Here is the SS image: (note the lack of detail in foliage)
    https://duaw26jehqd4r.cloudfront.net/items/1l2108272r0N161Y0i3P/Sec Spy 30-12-2018 09-00-59 East.jpg?v=9603a846

    Note: there is a slight over exposure issue too... a large dark mass of foliage is then dominated by a white truck and the autoexposure is unable to clamp down exposure in time. It is almost impossible to trigger motion detect accurately so trying to tweak the exposure response is unlikely to help. For oncoming traffic at night, even with IR illumination the exposure is dominated by the headlights so the captures are useless. Views of the rear of cars still require to under expose to get reg. plates readable. For the future it would be good to be able to have two exposure modes - one for IR and one for day.

    Note: the Motion capture in camera is basic Lo/med/high, without masks, so I'd prefer to use SS for captures (especially if it can pre-capture stills)
  • Yes I think you have a good point there with the VBR perhaps not being able to compensate fast enough for sudden movement - so try CBR with a high bit rate to see if that works better for you.

    The difference in quality does appear to be down to the encoding - whether this is the H.264 encoding provided by the camera, or the JPEG encoding performed by SS. First, try CBR with the maximum bit rate to test the camera's encoding, and then try increasing SecuritySpy's JPEG encoding quality to see if this makes a difference.
  • Thanks for the quick response Ben. I have put video bit rate up to 3000 and CBR. I had SS JPEG quality on 72 - I will up it to 82
  • I have now run it at 3000kbs date rate and CBR. The results seem much sharper in the trees.
    https://duaw26jehqd4r.cloudfront.net/items/3F2b0G1D102X0H1b423e/31-12-2018 11-38-00 East to Dunsfold.jpg?v=022b8f7f

    I have been tweaking the shutter speed - as fast moving objects will be blurred unless the shutter is fast.. and that reduces the camera's capability in lower light.
  • Thanks for following up - yes at 3000 kbps the sharpness seems much better.

    Out of interest, what shutter speed are you finding that works well for you?
  • It is difficult to say. The iGeek software has a shutter speed range of 1-10,000 The setting of 20 or 50 seems best compromise of still image capture of fast moving close vehicles, but at the cost of under exposing in poor light / dusk. I run the second camera at 1000 setting as that is on the front of the house with only humans in shot. So I am deducing the range is something like 10,000=1/10th sec and 50=1/2000th sec. The igeek iCam software has no support nor instructions.

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