What causes these ghost images?

Discussion in 'Dahua' started by Frankenscript, Aug 12, 2019 at 10:18 AM.

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  1. Frankenscript

    Frankenscript Pulling my weight

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    Hi folks,

    I recently tweaked my Dahua 5321R-Z settings, and while generally the images improved, I've noticed ghost images such as these now show. See the images of the tires ghost in repeatedly.
    Ghost images.png
    What do I need to adjust to eliminate or reduce this?

    I record 10 frames/sec on a shutter optimized exposure I think 0-7msec. Minimal noise reduction but NR isn't off. I think I had it set around 18 or so last time I checked.

    Note that the area of interest is actually the mailbox, not the road, but people walking by have similar ghost images... it was just easiest for me to grab this car image which clearly shows the ghosts.

    Thanks
     
  2. Walrus

    Walrus Pulling my weight

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    Does it do it during the day too? I get ghosting with newer intel drivers. I have to roll back to old 2016 drivers to get rid of ghosting. This is on a 6th gen i5 with HD 530 GPU.
     
  3. Frankenscript

    Frankenscript Pulling my weight

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    No, it's only at night. Or more to the point, it only impacts recordings made using the night settings of the camera. Everything looks great on daytime recordings.



    Sent from my ONEPLUS A6013 using Tapatalk
     
  4. Frankenscript

    Frankenscript Pulling my weight

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    Oh, and for clarity, I see the ghosting if I view the recording via mobile app too. It's not just an artifact of UI3 or some such... It seems to be in the recording itself (which is direct to disc) so I presume it has to do with camera configuration in Dahua's camera web interface.

    I'm using BI version 4.

    Sent from my ONEPLUS A6013 using Tapatalk
     
  5. Walrus

    Walrus Pulling my weight

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    In the camera settings, do you have the iframe interval set the same as the FPS? eg since you mentioned you are running 10FPS, set the iframe interval to 10 if you don't.
     
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  6. Frankenscript

    Frankenscript Pulling my weight

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    Hmmm. Iframe was set to 20. I changed it to 10 on one of the pair of cameras I'm seeing this on, and will look into this after I capture night images with the new setting. I'm away for a few days but will follow back up on this upon my return. Thank you.
     
  7. Walrus

    Walrus Pulling my weight

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    Whenever you change the frame rate on Dahua cameras, it automatically sets the iframe interval to double the frame rate. Some have suggested this can cause ghosting.
     
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  8. fenderman

    fenderman Staff Member

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    The ghosting seen here is due to noise reduction, wdr, and/or insufficient lighting. Issues seen with iframe intervals is tearing sometimes also called ghosting but appears differently.
     
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  9. bug99

    bug99 Pulling my weight

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    You need either more light on the target for the same shutter time (10x to 100X more, not 2x more) or you need to reduce the shutter time (which will darken the image, so you will need more light anyway). Don't increase the gain. It appears to be in B&W, so simply adding an external IR illuminator or two will likely fix the issue.
     
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  10. wopi82

    wopi82 Getting comfortable

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    It's a noise reduction ghosting. Nothing else. If you turn it off, ghosting will disappear. Try to lower it by half.
     
  11. Frankenscript

    Frankenscript Pulling my weight

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    Right, the iFrame change didn't eliminate the ghosting, so I will work on noise reduction minimization, as well as increasing IR illumination of the area. Thanks all.
     
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