This started as looking for a easy way to watermark some photos that I was going to expose to the whole world. The first thing that came into my mind was that I could use a specialized photo editing software (like Photoshop for example) to apply the watermarks. This had the drawback that you actually need  to have such a program and that it is a highly repetitive task which I wouldn’t want to do it over and over again for hundreds of pictures. (to be fair it’s probably possible to automate such a task, given that the photo editing software supports it, and again probably the software that supports it is not free).

What I wanted was a small command line utility that would take as input the image and produce as output the watermarked image. Really simple, right?

Well, believe it or not other people thought about it and there are some utilities like that out there. The problem is that people who wrote them actually expect you to buy them at prices over what they are really worth.

So what I did was remember a few basic things about the .NET Framework (which I knew better in a previous life) and try to put together a small utility on my own. It’s written in C# and you’ll need, at minimum, the .NET SDK to be able to compile it, but I would recommend Visual C# (even if it’s the free Express Edition).

.NET has decent support when it comes to working with images.

1) I’ll do this as a console application. So I’ll start from a blank class that has the entry point defined as

static void Main(string[] args)

2) We need to pass the file we are trying to watermark as parameter. We’ll not overwrite the file, we’ll create a new one that has a similar name but with w_ in front. So we add the following code:

if (args.Length == 1)
{
string file = args[0];
string filemod = “w_” + file;

file is the original filename passed as a parameter. filemod is the new filename which we built.

3) The next thing we want to do is open the image file and obtain a graphics object from it so we can draw on it. We’ll add the following lines to the if block previously started:

try
{
Image imageFile = Image.FromFile(file);
Graphics grp = Graphics.FromImage(imageFile);
}
catch (Exception e)
{
Console.WriteLine(“Something went wrong!”);
Console.WriteLine(e.Message+Environment.NewLine+e.StackTrace);
}

Note the minimal care for situations in which things go wrong (for example file is missing or we don’t have permissions to access it). This is done for the sake of keeping it simple. In case something goes wrong we’ll just let the one who uses the utility know.

Also please note that for this to work you also need a reference to System.Drawing assembly in your project.

4) Next step is to write on the image itself. We will need a font and a color. It would also be nice if the color was somewhat transparent. Let’s do it:

Image imageFile = Image.FromFile(file);
Graphics grp = Graphics.FromImage(imageFile);
int alpha = 60;
Color customColorSh = Color.FromArgb(alpha, Color.White);
Font fontUsed = new Font(“Verdana”, 15, FontStyle.Bold);
grp.DrawString(“Copyrighted image”, fontUsed, new SolidBrush(customColorSh), new PointF(10, 10));

Alpha is the transparency. We set it to 60%. The color is white. And we’ll draw the string at coordinates (10.10) – last parameter for DrawString.

5) At this moment the image is watermarked. The final step we need to do is save it. We’ll be using Jpeg encoder, if we can find one:

ImageCodecInfo jpegEncoderInfo = null;
ImageCodecInfo[] encoderInfoArray = ImageCodecInfo.GetImageEncoders();
foreach (ImageCodecInfo imageCodecInfo in encoderInfoArray)
{
if (0 == String.Compare(“image/jpeg”, imageCodecInfo.MimeType, true))
{
jpegEncoderInfo = imageCodecInfo;
}
}

// If a JPEG encoder was found, use it to save a Bitmap to a JPEG file,
// explicitly specifying a “quality” parameter of 100 (the maximum).
if (null != jpegEncoderInfo)
{
EncoderParameters encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
imageFile.Save(filemod, jpegEncoderInfo, encoderParameters);
}

That’s about it.

We have a basic command like watermark utility.

Here you can find the full source code: Program.cs

Here is a sample of an image before and after watermarking:

And here is the final form of the watermark utility I use for the pictures you can see in the Pictures section of this blog: Watermarker.exe (use it at your own risk – code is basically the same as in this tutorial just it applies text in a matrix. I’m not in any way responsible for pictures you might destroy misusing this or for the malfunctioning in any way of the utility)

Related posts:

1. Pictures from Multiple Cameras in Chronological Order
2. Leaving your mark… the obtuse edition
3. Taboo – American Teeth