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Editorial Team
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Asked: 2026-05-27T05:04:23+00:00

I have this gray video stream: The histogram of this image: The thresholded image

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I have this gray video stream:
enter image description here

The histogram of this image:

enter image description here

The thresholded image by :

  threshold( image, image, 150, 255, CV_THRESH_BINARY );

i get :

enter image description here

Which i expect.

When i do adaptive thresholding with :

adaptiveThreshold(image, image,255,ADAPTIVE_THRESH_GAUSSIAN_C, CV_THRESH_BINARY,15,-5);

i get :

enter image description here

Which looks like edge detection and not thresholding. What i expected was black and white areas . So my question is, why does this look like edge detection and not thresholding.

thx in advance

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1 Answer

  1. Editorial Team

    Adaptive Threshold works like this:

    The function transforms a grayscale image to a binary image according
    to the formulas:

        THRESH_BINARY

    THRESH_BINARY

        THRESH_BINARY_INV

    THRESH_BINARY_INV

    where T(x,y) is a threshold calculated individually for each pixel.

    Threshold works differently:

    The function applies fixed-level thresholding to a single-channel array.

    So it sounds like adaptiveThreshold calculates a threshold pixel-by-pixel, whereas threshold calculates it for the whole image — it measures the whole image by one ruler, whereas the other makes a new “ruler” for each pixel.

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