How to Overlay Images

namespace VObjectsSimpleCS
{
    public partial class Form1 : Form
    {
        string backgroundImageFilname = @"..\..\img1.JPG";
        string overlayImageFilename = @"..\..\img2.JPG";

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // Load the background and overlay bitmaps.
            Aurigma.GraphicsMill.Bitmap backgroundImage = new Aurigma.GraphicsMill.Bitmap(backgroundImageFilname);
            Aurigma.GraphicsMill.Bitmap overlayImage = new Aurigma.GraphicsMill.Bitmap(overlayImageFilename);

            // Load the backgroundImage to the BitmapViewer.
            bitmapViewer1.Bitmap = backgroundImage;

            // Create an image v-object which represents the overlay image.
            Aurigma.GraphicsMill.WinControls.ImageVObject vOverlayImage = new Aurigma.GraphicsMill.WinControls.ImageVObject(overlayImage, false, 0, 0);

            // Add the overlay v-object to a layer.
            vObjectsRubberband1.Layers[0].VObjects.Add(vOverlayImage);

        }

        private void _applyButton_Click(object sender, EventArgs e)
        {
            // Render the overlay v-object to a bitmap.
            Aurigma.GraphicsMill.Bitmap renderedImage = vObjectsRubberband1.RenderWorkspace();

            // Merge the overlay and background bitmaps.
            renderedImage.Draw(bitmapViewer1.Bitmap, 0, 0, bitmapViewer1.Bitmap.Width,
                bitmapViewer1.Bitmap.Height, Aurigma.GraphicsMill.Transforms.CombineMode.Alpha,
                1f, Aurigma.GraphicsMill.Transforms.InterpolationMode.HighQuality);

            // Save the merged bitmap to file.
            bitmapViewer1.Bitmap.Save(@"..\..\imgNew.JPG");

            renderedImage.Dispose();
        }
    }
}

namespace VObjectsMemoryFriendlyCS
{
    public partial class Form1 : Form
    {
        string backgroundImageFilname = @"..\..\img1.JPG";
        string overlayImageFilename = @"..\..\img2.jpg";

        private float _imageScale;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // Load the background image.
            Aurigma.GraphicsMill.Bitmap backgroundImageCopy = new Aurigma.GraphicsMill.Bitmap(backgroundImageFilname);

            // Get an initial width of the background image.
            float backgroundWidth = backgroundImageCopy.Width;

            // Resize the background image proportionally to a doubled BitmapViewer's width.
            backgroundImageCopy.Transforms.Resize(bitmapViewer1.Width * 2, 0);

            // Get the ratio of the initial background image width to the current width.          
            _imageScale = backgroundImageCopy.Width / backgroundWidth;
            
            // Load the overlay image.
            Aurigma.GraphicsMill.Bitmap overlayImageCopy = new Aurigma.GraphicsMill.Bitmap(overlayImageFilename);

            // Resize the overlay image proportionally to a half of the resized background image width.
            overlayImageCopy.Transforms.Resize(backgroundImageCopy.Width / 2, 0);            
            
            // Load the resized background image to the BitmapViewer.
            bitmapViewer1.Bitmap = backgroundImageCopy;

            // Create an image v-object which represents the resized overlay image.
            Aurigma.GraphicsMill.WinControls.ImageVObject vOverlayImage = new Aurigma.GraphicsMill.WinControls.ImageVObject(overlayImageCopy, false, 0, 0);

            // Add the overlay v-object to a layer.
            vObjectsRubberband1.Layers[0].VObjects.Add(vOverlayImage);
        }

        private void _applyButton_Click(object sender, EventArgs e)
        {
            // Load originals of the background and overlay bitmaps.
            Aurigma.GraphicsMill.Bitmap backgroundImageOriginal = new Aurigma.GraphicsMill.Bitmap(backgroundImageFilname);
            Aurigma.GraphicsMill.Bitmap overlayImageOriginal = new Aurigma.GraphicsMill.Bitmap(overlayImageFilename);

            // Get the GDI+ Graphics for the background image.
            System.Drawing.Graphics backgroundGraphics = backgroundImageOriginal.GetGdiplusGraphics();

            // Resize the overlay image proportionally to a half of the background image width.
            overlayImageOriginal.Transforms.Resize(backgroundImageOriginal.Width / 2, 0);

            // Get a matrix which contains all the transformations applied by a user to the overlay v-object.
            System.Drawing.Drawing2D.Matrix transform = vObjectsRubberband1.Layers[0].VObjects[0].Transform.Clone();

            // Since this matrix contains transformations applied to the resized overlay image
            // we should adapt it for use with the original overlay image.

            // During the adaptation we should take into account the following:
            // 1. The difference in sizes between the initial background image and the resized one.
            // 2. The difference in coordinate spaces between v-objects and bitmaps: v-objects coordinates are measured
            //    in points but bitmap dimensions - in pixels.

            // To translate pixels to points we should multiply the value in pixels by 72 and divide it by the current screen resolution.

            // Get a current screen resolution.
            float screenDpi = System.Drawing.Graphics.FromHwnd(IntPtr.Zero).DpiX;
            // Determine the pixels-to-points conversion coefficient.
            float pixelsToPoints = 72 / screenDpi;
    
            // Multiply the _imageScale by the pixels-to-points conversion coefficient to get the scale factor of transformation matrix.
            float scale = _imageScale * pixelsToPoints;

            // Adapt the transformation matrix.

            // Apply scale factor to transformation matrix by prepending.
            transform.Scale(scale, scale, System.Drawing.Drawing2D.MatrixOrder.Prepend);
            // Apply inversed scale factor to transformation matrix by appending.
            transform.Scale(1 / scale, 1 / scale, System.Drawing.Drawing2D.MatrixOrder.Append);

            // Merge the original overlay and background images using the adapted transformation matrix.

            // Apply transformations.
            backgroundGraphics.Transform = transform;
            // Draw the overlay image on the background.
            backgroundGraphics.DrawImage(overlayImageOriginal, 0, 0, overlayImageOriginal.Width, overlayImageOriginal.Height);

            // Save the merged bitmap to file.
            backgroundImageOriginal.Save(@"..\..\imgNew.JPG");

            backgroundImageOriginal.Dispose();
            overlayImageOriginal.Dispose();
            backgroundGraphics.Dispose();

        }
    }
}