New Post: Find subimage

var currentWebpageScreenshot = webPage.TakeScreenshotAsFile();
using (var imageA = new MagickImage(currentWebpageScreenshot))
using (var imageB = new MagickImage(screenshotFile))
using (var differenceImage = new MagickImage())
{
    var comparisonResult = imageA.Compare(imageB, Metric.RootMeanSquareError, differenceImage); // Exception here
    // some logic
}