Designers

//...
using AvlNet;
using AvlNet.Designers;
//...


    public partial class Form1 : Form
    {
        Region roi;
        /// <summary>
        /// image being thresholded
        /// </summary>
        Image image;

        public Form1()
        {
            InitializeComponent();
        }

        /// <summary>
        /// Loads an image
        /// </summary>
        private void image_Click(object sender, EventArgs e)
        {
            Image newImage = null;
            Image dummyImage = null;
            if (sender == lenaRgbBtn)
                AVL.TestImage(TestImageId.Lena, out newImage, out dummyImage);
            else if (sender == fromFileBtn)
            {
                if (openImageDialog.ShowDialog() == DialogResult.OK)
                {
                    try
                    {
                        AVL.LoadImage(openImageDialog.FileName, false, out newImage);
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show(ex.Message, "Loading error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                }
            }

            if (newImage != null && image != null && !image.IsDisposed)
                image.Dispose();

            if (newImage != null)
                image = newImage;

            if (dummyImage != null)
                dummyImage.Dispose();

            if (roi != null && (roi.FrameHeight > image.Height || roi.FrameWidth > image.Width))
            {
                AVL.CropRegion(
                    roi,
                    new Box(0, 0,
                        Math.Min(roi.FrameWidth, image.Width),
                        Math.Min(roi.FrameHeight, image.Height)),
                    out roi);
            }

            UpdatePreview();
            UpdateThresholdResult();
        }

        /// <summary>
        /// Performs image thresholding either in defined ROI or of a cropped image.
        /// </summary>
        private void UpdateThresholdResult()
        {
            if (image == null)
            {
                resultPreview.Image = null;
                return;
            }

            Image thresholdedImage = null;

                AVL.ThresholdImage(image, roi, minTrackBar.Value, maxTrackBar.Value, 1.0f, out thresholdedImage);

            if (thresholdedImage != null)
            {
                resultPreview.Image = thresholdedImage.CreateBitmap();
                thresholdedImage.Dispose();
            }
        }

        /// <summary>
        /// Updates loaded image miniature with drawn either a ROI or a box into with image is cropped
        /// </summary>
        private void UpdatePreview()
        {
            if (image == null || image.IsDisposed)
            {
                imagePreview.Image = null;
                return;
            }

            Image miniature = new Image(image);

            if (roi != null)
                AVL.DrawRegion(ref miniature, roi, Pixel.Blue, 0.5f);

            imagePreview.Image = miniature.CreateBitmap();

            miniature.Dispose();
        }

        /// <summary>
        /// Opens a RegionDesigner to edit a ROI within which an image will be thresholded.
        /// </summary>
        private void regionButton_Click(object sender, EventArgs e)
        {
            using (RegionDesigner designer = new RegionDesigner())
            {
                if (image != null)
                    designer.Backgrounds = new Image[] { image };

                designer.Region = roi;
                if (designer.ShowDialog(this) == DialogResult.OK)
                {
                    roi = designer.Region;
                }
            }

            UpdatePreview();
            UpdateThresholdResult();
        }

        private void trackBar_ValueChanged(object sender, EventArgs e)
        {
            UpdateThresholdResult();
        }