无法在画布上正确绘制

Question

<Window x:Class="ShelfMapping.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Shelf Mapping" Height="1080" Width="1920"
        Loaded="Window_Loaded" Unloaded="Window_Unloaded">
    <Grid>

        <Image Name="camera" />
        <Image Name="depthOut"/>
        <Canvas Name="canvas"/>

        <Grid Style="{StaticResource GridButtonsStyle}">
            <StackPanel Style="{StaticResource StackPanelButtonsStyle}">
                <Button Content="Screenshot" Style="{StaticResource ButtonStyle}" Click="buttonScreenshotClick" />
                <Button Content="OCR" Style="{StaticResource ButtonStyle}" Click="click_OCR" />
                <Button Content="Back to stream" Style="{StaticResource ButtonStyle}" Click="click_backToStream" />
                <TextBox Name="txtCode" Height="50" Width="150"/>

            </StackPanel>
        </Grid>

    </Grid>
</Window>

这是我的XAML文件。

Ellipse ellipse = new Ellipse();
                ellipse.Width = 20;
                ellipse.Height = 20;

                SolidColorBrush blueBrush = new SolidColorBrush();
                blueBrush.Color = Colors.Blue;
                SolidColorBrush redBrush = new SolidColorBrush();
                redBrush.Color = Colors.DarkRed;

                // Set Ellipse's width and color
                ellipse.StrokeThickness = 4;
                ellipse.Stroke = redBrush;
                // Fill rectangle with blue color
                ellipse.Fill = blueBrush;

                Canvas.SetLeft(ellipse, infoInt[0] - ellipse.Width / 2);
                Canvas.SetTop(ellipse, infoInt[1] - ellipse.Height / 2);

                canvas.Children.Add(ellipse);

这是我绘制点的地方。根据绘制在画布中其他位置的图像像素，点的输出是正确的。椭圆应该精确地绘制在数字上，但它是在其他地方绘制的。我不知道如何解决它。帮助我解决这个问题。