private void zielonyToolStripMenuItem_Click(object sender, EventArgs e)
{
savedBitmap.Push(new Bitmap(picture));
if (savedBitmap.Count() >= 0)
{
button1.Enabled = true;
}
PixelOperations pixelmod = new PixelOperations();
Picture = pixelmod.grayscale3(new Bitmap(picture));
}