You might already know that you can use digital watermarking to protect your work for copyright and data protection.

But do you know what are the different types of watermarks and when to use each?

Below, we’ll cover all the different watermarking types, examples, and give an overview as to when you should use each type of digital watermark.

By the end of the post, you’ll know everything about watermarking your PDFs (or other type of documents), protecting your work with copyright, and how to use each type of digital mark (with examples).

Here’s what we’ll cover:

• What Are Digital Watermarks And Why Do They Matter?
• 2 Main Types of Watermarks And When Should I Use Each? (With Examples)
• Why Are Digital Watermarks Important For PDF (Or Other) Documents And Files?
• How to Add Watermarks To Your Work - Examples And Step-By-Step Overview

Now, let’s get started.

What Are Digital Watermarks And Why Do They Matter?

To keep it simple, a watermark is a small message, for instance, your logo, superimposed onto the image or PDF document to show who it belongs to (i.e. your brand). 

It is placed in such a way that the image isn’t affected by its presence, for example, in the bottom corner. In PDFs and word documents, it is placed in a washed manner under the text, so that it doesn’t obstruct the actual message. 

But before you get started watermarking your documents, you should know what type of watermarks exist and when to use each, which is something we’ll cover below - with examples.

2 Main Types of Digital Watermarks And When to Use Each? (With Examples)

There are two main types of watermarks you should know about:

• Visible Watermarks.
• Invisible Watermarks.

Not sure what’s the difference or when to use each?

Let’s take a look at each example and cover all the details below.

Visible watermarks overview and examples

Visible watermarks, which are also known as transparent watermarks, are semi-transparent marks placed on the original image to showcase who the digital property belongs to. 

They usually are in the form of the company or artist’s logo who owns the copyright to it. They could also have the company or artist’s name. Sometimes, they contain the year when the image was clicked on too. 

The main purpose behind this logo is to showcase the copyright without compromising the image quality, and thus, it’s placed in a subtle manner, i.e., semi-transparent. 

So, that’s why it’s visible but transparent.

Even though it's essential to keep the visible watermark away from the major components of the photo, it shouldn’t be such that anyone could crop it and declare it their own. 

Photographers counter the cropping issue by placing watermarks throughout the image. Such watermarks are usually used when images are uploaded on stock image websites, such as Shutterstock. Those watermarks disappear when a user buys that image or downloads it after buying the website’s membership. 

Here’s an example of the most common type of visible watermark with the company logo:

You can find more examples of visible watermarks on most royalty-free image websites like Shutterstock, IStockPhoto, Adobe Stock, and so on.

When to use visible watermarks

So, when should you use a visible watermark?

You’ll want to use that type of watermark if:

• You want to preview your work and don’t want the person receiving them to pass it as their own (e.g. photography work, modeling, content creation, etc.).
• It’s important to showcase and highlight your brand.
• You want to show something as proof or previews.
• You want your work to look more professional and showcase that the work is important to you.

Invisible watermark overview and example

Invisible watermarks are often referred to as hidden or covert watermarks. As the name indicates, these watermarks are invisible, so the naked human eye can’t see them. To view them, you’ll need special steganography applications or tools. 

There are numerous types of invisible watermarks:

• Some of these watermarks are similar to visible watermarks, but they are so transparent that the naked human eye can’t see them. 
• The lowest-order bit of some specific pixels are flipped, which only works if the image is not changed. However, it’s too basic to use. 
• Spatial watermarking is another invisible watermarking technique. It uses a specific color band, which becomes visible when the colors are separated, for instance, during printing. 
• In frequency watermarking, the watermark is placed at a specific frequency and only becomes apparent when the frequency is separated.

In these aforementioned techniques, spatial and frequency watermarking are the most popular. 

We would provide an example image for an invisible watermark, but as the name implies, it’d just look like a regular image.

When to use invisible watermarks

The concept of invisible watermarking might seem weird as it's hard to locate these watermarks, but they are more beneficial as compared to the visible watermarks as it's difficult to erase them. 

Such watermarks come in handy in copyright investigations as they are not visible and often go undetected. Invisible watermarks help with forensics, traitor tracing, copyright, proof of ownership, and other steganography concepts.

So, in most cases, unless you’re dealing with very sensitive information with potential of leaked information, you’re probably better off using visible watermarks.

Why Are Digital Watermarks Important For PDF (Or Other) Documents And Files?

Saving images on the internet is quite easy these days. All people have to do is right-click, save the image, and then they can pass it as their own. Creating original content and making it presentable via editing takes significant energy and finances, therefore, risking it to be stolen isn’t wise. Putting your or your company’s logo or name on it subtly can save you from other people claiming your work.

The absence or compromising of watermarks can also lead to unauthorized use and distribution. 

Watermarks show that a certain image is only for viewing and not for sharing. 

But aside from marking your work, sometimes, internal private media libraries get compromised. Or it becomes unclear whether an image is only for internal use, or could be shared, leading to accidental sharing by the employees. This could lead to misinformation and tarnish your company’s name. 

So, while you shouldn't be watermarking all of your images and digital assets, you should keep in mind some general best practices.

When to watermark images and files

When to watermark your images and PDFs:

• You’re a freelancer, service provider, or a business owner sharing a preview of your previous work to a potential client.
• Your work is sensitive and/or people would need to buy extra to view the full image (e.g. like Shutterstock).
• The said work is sensitive in nature and it’ll be forwarded to many people. It’s not for public consumption, so in the case it leaks, you’ll know people can’t pass it as their own.
• You’re creating an online portfolio, case studies, or showing off sample work on your site.

When to NOT watermark your images and PDFs:

• If you’re creating marketing materials or content, in which the watermark would just decrease the consumption experience.
• If you’re creating free PDF documents for your audience, and you want them to gain the most value out of it.
• If it’s already obvious the work they’re viewing is yours and/or you already have your logo and credentials in the asset.

Now, in case you’re wondering how to watermark your work, let’s take a look at some examples and how to watermark your work (both, for invisible and visible watermarks).

How to Add Watermarks To Your Work - Examples And Step-By-Step Overview

In this section, we’ll share a number of different ways you can add watermarks to your images. 

How to add visible watermarks in GIMP (Step-by-step)

There are multiple software through which you can put visible watermarks onto your images. Some of them are free while the others are paid. 

In this post, we’ll be showing you how to add watermarks to your work for free with GIMP, which is available on all types of major platforms, such as Linux, Windows, and Mac. This software is free, and has a decent set of features. 

Here’s how to watermark your work for free with GIMP.

1. Download and install GIMP
2. Open your image in GIMP.
3. Go to the ‘File’ section, and click on ‘Open’. Navigate to the image that you want to open and click on ‘Open’.

4. Select the Text tool from the left pane. It looks like a capital ‘A’. Now click on the image where you want to add text and a textbox will appear. 

When creating a textbox, a menu will pop up with the font, text size, and a few other customization options. If you want even more flexibility, then right-click to get more choices, such as changing the writing position from left to right to right to left. 

You can also add an image or a logo to the image by clicking on ‘File’, and choosing ‘Open as layers’.

Navigate to where the logo is located and open it. Next, select the ‘Move’ tool from the left pane and place the logo where you want it to be. Usually the center of your image works well with a visible watermark.

5. Adjust the opacity. 

After you are happy with your text or image, adjust its opacity. You can do this through the layers tab, where you’ll notice a new layer has been added after you input the text or image. To adjust the opacity, you’ll have to select the logo or text. 

6. Export the image. 

After you are happy with the results, save the copyrighted image either as JPEG (.jpg) or PNG (.png). We are suggesting these formats because they combine both the text and image into a single layer. You can do this by clicking ‘File’ and then ‘Export’. 

How to add invisible watermarks in GIMP (Step-by-step)

You can also use GIMP to add invisible watermarks as well. However, for this, you’ll need to download GMIC. You can download it by going to this link: https://gmic.eu/download.html

Here’s how you can put invisible watermarks using GIMP and GMIC:

1. Open the image

Go to ‘File’ and click on ‘Open’. Navigate to the image that you want to open, select it, and click ‘Open’. 

2. Create Layers

Click on ‘Filters’ and choose ‘G’MIC-Qt’. 

Then, click on ‘Frequencies’ and then, ‘Fourier Watermark’. 

Click on the Text bar in the right pane, enter your desired text, and choose the size. On the lower right corner, you’ll see ‘Output mode’, select ‘New layer(s)’ from the dropdown. Click on ‘Apply’.

Next, click on ‘Fourier Transform’ and select ‘Two Layers’ from ‘Magnitude/Phase’. 

Change ‘Input Layers’ to ‘Active (default)’ and ‘Output Layers’ to ‘In place (default)’. Hit ‘Apply’ and then ‘Ok’. You’ll see two new layers in the right pane. 

3. Write your watermark text

Open the ‘Fourier Transform’ layer. Then click on the capital ‘A’ in the left pane for inserting text. Type whatever text you want on that image. You’ll notice a text layer has been added, move it to the top in the layers list. 

4. Duplicate your Watermark

Go to ‘View’ and check ‘Snap to Canvas Edges’. 

Now, use the move tool and snap the text to the edges of the image. After this, go to ‘Layers’, select ‘Layer to Image Size’, and duplicate the layer by clicking on the duplicate icon on the bottom right. 

Next, press Shift + F to start the Flip tool. Click anywhere on the canvas, your initial text will be duplicated on the bottom corner. Press Ctrl or Command and click on the canvas again to create a new watermark on the opposite corner. 

5. Merge your layers

Now right click on the layer and click on ‘Merge down’ and press duplicate. Once again, right-click on the layer and click on ‘Merge down’. Reduce the opacity to 60 to 70%. Right-click again and press on ‘Merge down’. 

After that, go to ‘Filters’ and open ‘G’MIC-Qt’ again. Go to ‘Fourier Transform’ and change the ‘Input Layers’ to ‘Active and Below’. Click on ‘Ok’ and you’ll notice that all the layers are gone but you have two identical images left. There will be a slight difference between both images, but you can keep it to a minimum by keeping the text size small. 

Conclusion

Hope you found this guide useful next time you’re creating and adding watermarks to your documents!

To recap, there are 2 types of digital watermarks:

• Visible watermarks - Semi-transparent marks placed on the original image to showcase who the digital property belongs to.
• Invisible watermarks - Watermarks the naked human eye can’t see, useful for copyright investigations, forensics, traitor tracing, copyright, proof of ownership, and so on.

If you want to add watermarks to your images, you can do that for free with GIMP.

Meanwhile, if you want to add watermarks to your PDFs, you can use Adobe Acrobat.

Looking for better ways to manage your PDFs?

Check out Inkit Render and start converting, managing, and organizing your PDFs!