Created a bitmap variable to get a pixel colour, how do I stop using the file so I can file.delete it

Question

I have a simple alert form which pops up, and I'm trying to have different messages depending on a colour of a pixel in an image, the alerts' load code is is:

        private void Alert_Load(object sender, EventArgs e)
        {
            Bitmap myBitmap = new Bitmap(Properties.Settings.Default.AlertFile);
            Color pixelColor = myBitmap.GetPixel(50, 50);
            File.Delete(Properties.Settings.Default.AlertFile);

            if (pixelColor == Color.FromArgb(255, 237, 28, 36))//red
            {
                AlertMessage.Text = "Test Message 1: It is Red";
            }
            else
            {
                AlertMessage.Text = "Test Message 2: It isn't Red";
            }

            TopMost = true;
        }

Regardless of where the File.Delete line is, I get the message that the file is in use, and can't be deleted.

I've had this issue before using FileSystemWatcher where I couldn't delete the file as it was still being used, and I had to stop the watcher, but in this situation I don't know how to solve it.

The file starts being used here:

        Bitmap myBitmap = new Bitmap(Properties.Settings.Default.AlertFile);

I've tried adding:

myBitmap.Dispose();

But I still get the message it is in use.

Edit:

Fixed with Using

            Color pixelColor;
            using (var AlertImage = new Bitmap(Properties.Settings.Default.AlertFile))
            {
                pixelColor = AlertImage.GetPixel(50, 50);
                AlertImage.Dispose();
                File.Delete(Properties.Settings.Default.AlertFile);

                if (pixelColor == Color.FromArgb(255, 237, 28, 36))
                {
                    AlertMessage.Text = @"It was Red :)";
                }
                else
                {
                    AlertMessage.Text = @"It was not Red :(";
                }
            }

Answer 1

Try adopt Using Statement that provides a convenient syntax that ensures the correct use of IDisposable objects like File or Bitmap .

This is the correct syntax: you don't need to call .Dispose on AlertImage .

Color pixelColor;

using (var AlertImage = new Bitmap(Properties.Settings.Default.AlertFile))
{
    pixelColor = AlertImage.GetPixel(50, 50);
}

File.Delete(Properties.Settings.Default.AlertFile);

if (pixelColor == Color.FromArgb(255, 237, 28, 36))
{
    AlertMessage.Text = @"It was Red :)";
}
else
{
    AlertMessage.Text = @"It was not Red :(";
}