private ImageSource _imageSource;
    public ImageSource ImageSource
    {
        get => _imageSource;
        set => SetProperty(ref _imageSource, value);
    }

// 加載圖片方法
    public void LoadImage(string path)
    {
        var bitmap = new BitmapImage();
        bitmap.BeginInit();
        bitmap.UriSource = new Uri(path, UriKind.Absolute);
        bitmap.CacheOption = BitmapCacheOption.OnLoad; // 非常關鍵
        bitmap.EndInit();
        bitmap.Freeze(); // 讓圖片可以跨線程訪問，性能好
        ImageSource = bitmap;
    }

前臺顯示
<ImageBrush ImageSource="{Binding ImageSource}"/>