Image Acquisition from 8K Monochrome line scan camera - 8 tap mode - Scrambled image from Marathon VCL

  • Dear SISO & Members,

    We have built an applet to capture image from 8K monochrome line scan camera which is running in Full mode 8K 8 tap based on Encoder (50KHz) and Image trigger. Attaching the VA file for your reference.

    Foil_8K_V1.3_Marathon.va

    Most of the captured images are ok. But randomly the pixels are getting jumbled as shown below:

    pasted-from-clipboard.png


    We are doubting that the issue is with the mage Buffers. Can anyone help us out what is wrong with the Image acquisiton part in the attached VA?

    Thanks in advance,

    Arjun

  • Hi Arjun,


    do you have a specific reason to use two SignalGate operators?

    Do you use that for your tap sorting?

    I wouldn't recommend that, because for the signal based paths there is no internal synchronisation.


    If I'm right with tap sorting: what camera do you use?


    Greetings,

    Simon

  • Dear Simon,

    We are not using 2 nos of Signal Gate operators for tap sorting. In our application, the frame triggers can have jitters such a way that the 2 nd trigger might come when the Signal Gate operator is busy with the 1 st trigger. So the triggers are split into odd and even, sent to separate Signal Gate and separate Images Buffers and later sequenced using Insert Image operator.


    Thanks,

    Arjun

  • Thank you for your reply.

    I can't find something obvious, which may cause your Problems.

    Have you double checked with the standard acquisition applet?

    Maybe there is a problem with your CL cabling, or your encoder debounce is to short.


    Do you have simulation images?


    Greetings,

    Simon

  • Dear Simon,

    The issue doesn't happen with standard acquisition applet. It happens only with this applet and as I said earlier, it doesn't happen always. It is random in nature.


    I am doubting the way ImageBuffer operator is handled in the background by VA. Because in the sample image I shared, there are two images overlapped (may be previous and current - I am not sure) in alternative columns.


    Hope will get a response from VA technical team to clarify this.


    Thanks,

    Arjun

  • Hello Arjun


    so you are saying the SignalGate operators switch between whole frame and not lines. So the error will be very unlikely at this position. Even though you have to be very careful that you get an even distribution of even and odd images for the buffers.


    Could you check the fill levels at all ImageBuffer operators during acquisition? Is any of the operator fill level > 50%?


    I think there is an error in module DocID. PulseCount will generate a pixel with every clock cycle. SYNC operator will perform a 0D to 2D synchronization. So for both inputs one pixel is required. This will most likely generate blocking signals at the SYNC input and cause ImageBuffer overflows. However you are saying it is working sometimes. I would assume it cannot work at all. So my assumption might be incomplete.

    pasted-from-clipboard.png


    I changed the design. See attached.


    Let us know your results.


    Johannes

  • While I was thinking about this again I figured out that my assumption is wrong.

    This will most likely generate blocking signals at the SYNC input and cause ImageBuffer overflows.

    The blocking signals will be generated at the second input. So PulseCounter is stopped while being unstoppable. So the implementation might cause a wrong synchronization but cannot explain the errors you see.


    Anyway please comment my first two phrases.

    ... so you are saying the SignalGate operators switch between whole frame and not lines. So the error will be very unlikely at this position. Even though you have to be very careful that you get an even distribution of even and odd images for the buffers.


    Could you check the fill levels at all ImageBuffer operators during acquisition? Is any of the operator fill level > 50%?

    Johannes

    Johannes Trein
    Teamleader Applications and Development
    SiliconSoftware GmbH
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