This sample shows how to use mask images.

You can add a transparent image to your PDF document using PdfDocument.AddImage method with a mask image as a parameter. Mask image must have the same width and height as an image to be made transparent and their pixel data must be encoded using 1 bit per pixel.

All pixels in the resulting image that correspond to the black pixels of a mask image will be drawn unchanged. All pixels in the resulting image that correspond to the white pixels of a mask image will not be drawn. Black pixels in a mask image are encoded using '0' bits. White pixels in a mask image are encoded using '1' bits.

C#
using System.Diagnostics;
using System.Drawing;

namespace BitMiracle.Docotic.Pdf.Samples
{
    public static class ImageMasks
    {
        public static void Main()
        {
            // NOTE: 
            // When used in trial mode, the library imposes some restrictions.
            // Please visit http://bitmiracle.com/pdf-library/trial-restrictions.aspx
            // for more information.

            string pathToFile = "ImageMasks.pdf";

            using (PdfDocument pdf = new PdfDocument())
            {
                PdfCanvas canvas = pdf.Pages[0].Canvas;
                canvas.Resolution = 150;

                canvas.Brush.Color = new PdfRgbColor(0, 255, 0);
                canvas.DrawRectangle(new RectangleF(50, 450, 1150, 150), PdfDrawMode.Fill);

                PdfImage image = pdf.AddImage("Sample data/pink.png", "Sample data/pinkMask.tif");
                canvas.DrawImage(image, 550, 200);

                pdf.Save(pathToFile);
            }

            Process.Start(pathToFile);
        }
    }
}
VB
Imports System.Diagnostics
Imports System.Drawing

Imports BitMiracle.Docotic.Pdf

Namespace BitMiracle.Docotic.Pdf.Samples
    Public NotInheritable Class ImageMasks
        Public Shared Sub Main()
            ' NOTE: 
            ' When used in trial mode, the library imposes some restrictions.
            ' Please visit http://bitmiracle.com/pdf-library/trial-restrictions.aspx
            ' for more information.

            Dim pathToFile As String = "ImageMasks.pdf"

            Using pdf As New PdfDocument()
                Dim canvas As PdfCanvas = pdf.Pages(0).Canvas
                canvas.Resolution = 150

                canvas.Brush.Color = New PdfRgbColor(0, 255, 0)
                canvas.DrawRectangle(New RectangleF(50, 450, 1150, 150), PdfDrawMode.Fill)

                Dim image As PdfImage = pdf.AddImage("Sample data/pink.png", "Sample data/pinkMask.tif")
                canvas.DrawImage(image, 550, 200)

                pdf.Save(pathToFile)
            End Using

            Process.Start(pathToFile)
        End Sub
    End Class
End Namespace