Assertion Failed (Size.Width>0 && Size.Height>0)

Assertion failed (size.width0 && size.height0)

I tried your code and for me it works (it visualizes the current webcam input)!

I ran it on Visual Studio 2012 Ultimate with OpenCV 2.4.7.

...

The error occurs because the image is empty, so try this:

while (true) {
    cap >> image;

    if(!image.empty()){
        imshow("window", image);
    }

// delay 33ms
waitKey(33);        
}

Maybe the first image you receive from your webcam is empty. In this case imshow will not throw an error. So hopefully the next input images are not empty.

OpenCV Error: Assertion failed (size.width0 && size.height0) simple code

This error means that you are trying to show an empty image. When you load the image with imshow, this is usually caused by:

1. The path of your image is wrong (in Windows escape twice directory delimiters, e.g. imread("C:\path\to\image.png") should be: imread("C:\\path\\to\\image.png"), or imread("C:/path/to/image.png"));
2. The image extension is wrong. (e.g. ".jpg" is different from ".jpeg");
3. You don't have the rights to access the folder.

A simple workaround to exclude other problems is to put the image in your project dir, and simply pass to imread the filename (imread("image.png")).

Remember to add waitKey();, otherwise you won't see anything.

You can check if an image has been loaded correctly like:

#include <opencv2\opencv.hpp>
#include <iostream>
using namespace cv;

int main()
{
    Mat3b img = imread("path_to_image");

    if (!img.data)
    {
        std::cout << "Image not loaded";
        return -1;
    }

    imshow("img", img);
    waitKey();
    return 0;
}

Assertion failure : size.width0 && size.height0 in function imshow

The image fails to load (probably because you forgot the leading / in the path). imread then returns None. Passing None to imshow causes it to try to create a window of size 0x0, which fails.

The poor error handling in cv probably owes to its quite thin wrapper layer on the C++ implementation (where returning NULL on error is a common practice).

OpenCV(4.2.0) error: (-215:Assertion failed) size.width0 && size.height0 in function 'cv::imshow'

Basically, this error tells you that you are trying to show an empty / non existent image. Please do check:

• The path: I think the problem comes from cv2.imread(). If the path is incorrect, the img variable will be empty.

The way you tried to read the image is almost right:

img = cv2.imread(C:\Users\someone\Documents\python\____The Useless Installer____\PY\colorpic)

The way it should be:

• double backslash for escaping the "\" character which has a special meaning in programming languages
• you do need to enter the format of the picture (jpeg, png, etc..).
• you need to pass this argument as a 'string' or "string"

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Therefore try img = cv2.imread("C:\\Users\\someone\\Documents\\python\\____The Useless Installer____\\PY\\colorpic.jpg")

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