threshold

Usage

Used for image binarization. It compares the pixel values in an image with the specified threshold and creates a binary image that contains only two values based on the comparison result.

Interface

double threshold(InputArray src, OutputArray dst, double thresh, double maxval, int type);

Parameters

Parameter	Description	Value Range	Input/Output
src	Input image.	Not null	Input
dst	Output image.	Mat class	Output
thresh	Threshold.	(-inf, inf)	Input
maxval	Maximum value to be assigned to pixels that satisfy the threshold condition.	(-inf, inf)	Input
type	Threshold type.	THRESH_BINARY, THRESH_BINARY_INV, THRESH_TRUNC, THRESH_TOZERO, and THRESH_TOZERO_INV	Input

Return Value

Threshold

Example

#include <opencv2/opencv.hpp>
#include <iostream>

int main() {
    // Create a 5x5 grayscale image.
    cv::Mat src = (cv::Mat_<uint8_t>(5, 5) << 50, 50, 50, 50, 50,
                                               50, 150, 150, 150, 50,
                                               50, 150, 200, 150, 50,
                                               50, 150, 150, 150, 50,
                                               50, 50, 50, 50, 50);

    // Apply the binarization threshold. Set the threshold to 100 and the maximum value to 255.
    cv::Mat dst;
    cv::threshold(src, dst, 100, 255, cv::THRESH_BINARY);

    // Output image
    std::cout<< dst << std::endl;

    return 0;
}

Output:

[[  0   0   0   0   0]
 [  0 255 255 255   0]
 [  0 255 255 255   0]
 [  0 255 255 255   0]
 [  0   0   0   0   0]]

Parent topic: Interface Definition