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TDA4VM: Output of threshold node is blank

Prithvi Kambhampati
Prodigy 235 points
Part Number: TDA4VM

Hi,

For our application we are using the following pipeline:

capture->viss->ldc->gaussian_filter->threshold->erode->dilate->display. We converted the output of LDC to VX_DF_IMAGE_U8 which is what the GaussianNode takes as input. We are able to view the output of gaussian on the display as well. When I try to view the output of threshold (binary) I get a blank screen with the border flashing. The performance statistics show that all the nodes are running. We also tried 'capture->viss->ldc->mosaic->gaussian->threshold->erode->dilate->display` but with the same output.

Are there any examples on using the threshold node?

Is there something we are missing? Let me know if you need further information from me.

The output is as below:

  • 0
    TI__Guru**** 477995 points

    Prithvi,

    That's expected, isn't it?

    The output of the threshold node is just binary, ie true or false. So depending on the threshold (or range), the output is just 0 or 1. This is just too less value for the display..

    You could find more information about threshold node from 

    And also example for the threshold node in conformance test in the file tiovx\conformance_tests\test_conformance\test_threshold.c

    Rgds,

    Brijesh

  • 0 in reply to Brijesh Jadav
    Prodigy 235 points

    Hi Brijesh,

    Thank you for the info. The documentation you attached is the information we used to build our node. We tried different threshold values (10, 50, 150, 200) with the camera pointed at different scenes but the output of threshold is not changing from the video attached above. Let me know if you need further information.

    Regards,

    Prithvi

  • 0 in reply to Prithvi Kambhampati
    TI__Guru**** 477995 points

    Hi Prithvi,

    do you mean you just see white pixels on the border of the image? 

    In the graph, after threshold node, i also erode and dilate nodes, i am not sure if they are configured correctly. 

    Just for this experiment, can you try connecting threshold directly to display and see if the output changes when scene changes?

    Regards,

    Brijesh 

  • 0 in reply to Brijesh Jadav
    Prodigy 235 points

    Hi Brijesh,

    Sorry for the delayed response. I tried to display the threshold node output but it is similar to the video attached previously. The display image is black with a white border coming up once in a while. I also removed the threshold node and used erode, dilate, and minmaxloc nodes and the output is as expected for them. I am able to see the output of dilate node and print the maxvalcount (last output of the minmaxloc node) on the terminal.

    Regards,

    Prithvi 

  • 0 in reply to Prithvi Kambhampati
    TI__Guru**** 477995 points

    Hi Prithvi,

    I am surprised by the white border line than the black display. Display would be black because threshold node will just output o or 1, which is very less value for 8bit display.. So threshold output will just look black.. 

    One thing to note is, are the display and threshold output resolutions same? 

    Also Can you save the output frame threshold node and analyze it offline, especially around the border? 

    Regards,

    Brijesh