/// <summary>
/// Compares two images and highlights the comparison result with red color.
/// </summary>
/// <param name="image1Filename">The filename of first image.</param>
/// <param name="image2Filename">The filename of second image.</param>
/// <param name="resultFilename">The filename of result image.</param>
public void CompareImages(string image1Filename, string image2Filename, string resultFilename)
{
    // open the first image
    using (Vintasoft.Imaging.VintasoftImage image1 = new Vintasoft.Imaging.VintasoftImage(image1Filename))
    {
        // open the second image
        using (Vintasoft.Imaging.VintasoftImage image2 = new Vintasoft.Imaging.VintasoftImage(image2Filename))
        {
            // create the image comparison command
            Vintasoft.Imaging.ImageProcessing.ImageComparisonCommand imageComparison =
                new Vintasoft.Imaging.ImageProcessing.ImageComparisonCommand(image2);
            
            // get the grayscale result of comparing two images
            using (Vintasoft.Imaging.VintasoftImage differences = imageComparison.Execute(image1))
            {
                // creates the colors for the differences palette with the red color as main color
                int[] colors = CreateDifferencesPaletteColors(System.Drawing.Color.Red);
                differences.Palette.SetColors(colors);
            
                // if pixel format of image1 is not Bgr24 or Bgr32 or Bgra32
                if (image1.PixelFormat != Vintasoft.Imaging.PixelFormat.Bgr24 && 
                    image1.PixelFormat != Vintasoft.Imaging.PixelFormat.Bgr32 && 
                    image1.PixelFormat != Vintasoft.Imaging.PixelFormat.Bgra32)
                {
                    // change pixel format of image1 to Bgr24
                    Vintasoft.Imaging.ImageProcessing.ChangePixelFormatCommand changeFormat = 
                        new Vintasoft.Imaging.ImageProcessing.ChangePixelFormatCommand();
                    changeFormat.PixelFormat = Vintasoft.Imaging.PixelFormat.Bgr24;
                    changeFormat.ExecuteInPlace(image1);
                }
            
                // if image1 and the comparison result image have different sizes
                if (image1.Width != differences.Width || image1.Height != differences.Height)
                {
                    // crop image1 to the comparison result image size
                    Vintasoft.Imaging.ImageProcessing.CropCommand crop = 
                        new Vintasoft.Imaging.ImageProcessing.CropCommand();
                    crop.RegionOfInterest = 
                        new Vintasoft.Imaging.RegionOfInterest(0, 0, differences.Width, differences.Height);
                    crop.ExecuteInPlace(image1);
                }
            
                // draw the comparison result on the top of image1
                System.Drawing.Graphics differencesGraphics = image1.OpenGraphics();
                differences.Draw(
                    differencesGraphics, 
                    new System.Drawing.Rectangle(0, 0, differences.Width, differences.Height)); 
                image1.CloseGraphics();
            
                // save the processed image to the new file
                image1.Save(resultFilename);
            }
        }
    }
}
            
/// <summary>
/// Creates the colors for the differences palette.
/// </summary>
/// <param name="color">Main color for the differences palette.</param>
/// <returns>The colors for the differences palette.</returns>
private int[] CreateDifferencesPaletteColors(System.Drawing.Color color)
{
    int[] colors = new int[256];
    for (int i = 0; i < 256; i++)
    {
        byte alpha = (byte)i;
        colors[i] = (alpha << 24) | (color.R << 16) | (color.G << 8) | color.B;
    }
    return colors;
}