private async void btnNegative_Click(object sender, EventArgs e) { btnNegative.Enabled = false; Bitmap resultImg = await Task.Run(() => Contrast.Negative(state.Image)); state.Edit(resultImg); pictureViewer2.Image = state.Image; await pictureViewer2.HistogramView(); await pictureViewer2.GrayBandView(); btnNegative.Enabled = true; }