Skip to content
opencv-wasm

findNonZero

Core and matricesfunctionOpenCV 5.0.0
import { findNonZero } from '@banou/opencv-wasm'

Use after await initOpenCV(). See the initialization and named imports guide.

ARGUMENTSsrc, idx
FUNCTIONfindNonZero
RETURN TYPEvoid
Call structure. A void return can still write to destination arguments. The parameter descriptions define inputs, outputs and ownership.

Returns the list of locations of non-zero pixels

Given a binary matrix (likely returned from an operation such as threshold(), compare(), >, ==, etc, return all of the non-zero indices as a cv::Mat or std::vectorcv::Point (x,y) For example:

    cv::Mat binaryImage; // input, binary image
    cv::Mat locations;   // output, locations of non-zero pixels
    cv::findNonZero(binaryImage, locations);

    // access pixel coordinates
    Point pnt = locations.at<Point>(i);

or

    cv::Mat binaryImage; // input, binary image
    vector<Point> locations;   // output, locations of non-zero pixels
    cv::findNonZero(binaryImage, locations);

    // access pixel coordinates
    Point pnt = locations[i];

The function do not work with multi-channel arrays. If you need to find non-zero elements across all the channels, use Mat::reshape first to reinterpret the array as single-channel. Or you may extract the particular channel using either extractImageCOI, or mixChannels, or split.

Note: - CV_16F/CV_16BF/CV_Bool/CV_64U/CV_64S/CV_32U are not supported for src.

  • If only count of non-zero array elements is important, countNonZero is helpful.
  • If only whether there are non-zero elements is important, hasNonZero is helpful.

See: countNonZero, hasNonZero

findNonZero(src: Mat, idx: Mat): void;
src

single-channel array

idx

Output destination, filled by the native operation. the output array, type of cv::Mat or std::vector<Point>, corresponding to non-zero indices in the input

Upstream declaration ↗

These signatures describe this package. Upstream documentation can mention optional backends that are absent from this build. Check runtime compatibility before choosing a backend or file format.