Create Image Mask

//Load the bitmap
Bitmap image = (Bitmap)Image.FromFile("image.png");

//Get the bitmap data
var bitmapData = image.LockBits (
    new Rectangle (0, 0, image.Width, image.Height),
    ImageLockMode.ReadWrite,
    image.PixelFormat
);

//Initialize an array for all the image data
byte[] imageBytes = new byte[bitmapData.Stride * image.Height];

//Copy the bitmap data to the local array
Marshal.Copy(bitmapData.Scan0,imageBytes,0,imageBytes.Length);

//Unlock the bitmap
image.UnlockBits(bitmapData);

//Find pixelsize
int pixelSize = Image.GetPixelFormatSize(image.PixelFormat);

// An example on how to use the pixels, lets make a copy
int x = 0;
int y = 0;
var bitmap = new Bitmap (image.Width, image.Height);

//Loop pixels
for(int i=0;i<imageBytes.Length;i+=pixelSize/8)
{
    //Copy the bits into a local array
    var pixelData = new byte[3];
    Array.Copy(imageBytes,i,pixelData,0,3);

    //Get the color of a pixel
    var color = Color.FromArgb (pixelData [0], pixelData [1], pixelData [2]);

    //Set the color of a pixel
    bitmap.SetPixel (x,y,color);

    //Map the 1D array to (x,y)
    x++;
    if( x >= bitmap.Width)
    {
        x=0;
        y++;
    }

}

//Save the duplicate
bitmap.Save ("image_copy.png");