This is a continuation of my blog post on intro to digital watermarking. In that post, we discussed what digital watermarking is and how it can be achieved. Here, we will discuss the intuition behind image watermarking and a few techniques that can be used. If you look at enough number of images, you will realize that not all of them are equally suited for watermarking. At least, we cannot use the same criteria to watermark all the images. How do we know where to watermark an image? Are there any rules or do we just place some watermark randomly in an image? Does it make a difference? Continue reading “The Intuition Behind Image Watermarking”
Tag: Pixel
Digital Watermarking
Let’s say you want to verify the authenticity of a signal. The signal can take any form like an image, audio, video, or any other kind of bit stream. By now, everybody would have heard the term “watermark” being used in the general sense. The most common example would be currency notes. Watermarks are embedded to verify the authenticity of the notes. But how do we achieve that with more complicated signals? As things move into the virtual world, where the threats are elevated to a much higher and abstract level, we need a way to verify the authenticity of different forms of digital signals. How do we do it? Continue reading “Digital Watermarking”
Image Steganography
As discussed in my previous post, steganography is the art of hiding the fact that communication is taking place. We achieve this by hiding original information inside other information known as carrier files. Many different carrier file formats can be used, but digital images are the most popular because of their frequency of occurrence on the internet. For hiding secret information in images, there exists a large variety of steganographic techniques, some are more complex than others, and all of them have respective strong and weak points. Different applications have different requirements of the steganography technique used. For example, some applications may require absolute invisibility of the secret information, while others require a larger secret message to be hidden. How do we achieve this? How robust is it? Continue reading “Image Steganography”
Panoramic Images
Consider a situation where you are standing on top of a mountain or some other beautiful natural scenery. You are enjoying a beautiful view that seems to span from far left to far right and you want to take a nice picture of the whole thing. Your camera allows you to capture only a limited field of view. So to capture the whole scene, you will have to capture multiple images. Doesn’t feel exactly the same watching it in pieces, does it? We really want to capture the beauty within a single image. You can certainly record a video and capture the whole scene, but what if you want to print it out? This is where panoramic photography technique comes in. Panoramic images are images with elongated field of view. The image above is one such example. These images cannot be captured with a single camera click because the field of view is limited. So how do we do capture panoramic images? Continue reading “Panoramic Images”
Fingerprint Recognition
Fingerprint recognition was one of the first forms of biometric authentication techniques developed. Biometric authentication refers to the process of identifying humans by their natural traits. This can include fingerprints, face, voice, iris etc. When you want machines to authenticate a particular person, you choose a feature of that person which he cannot control. Fingerprints are still widely used in criminal investigations and in certain other domains where security is required. Have you ever wondered if fingerprints are distinct enough to be used to identify a person? How do they match fingerprints? Continue reading “Fingerprint Recognition”
Touch Me Not
We are increasingly moving towards touchscreen technology. Every new mobile gadget that’s coming to the market has a touchscreen. Most of us interact with touchscreen technology on a daily basis. I’m sure you would have gotten curious some time or the other to know how it actually works. What happens when you touch the screen? How does it know where you touched the screen? All of us deserve to know how it works, especially when we use it so often. Continue reading “Touch Me Not”
Understanding Camera Resolution
Cameras are being embedded everywhere. We find them on our phones, tablets, laptops and other types of gadgets as well. Digital cameras are getting sharper and smarter by the day. Some cameras capture good quality pictures while some cameras don’t. We frequently come across the camera specs which mention the ‘MP’ value of the camera. You understand the fact that a 12MP camera takes better pictures than a 5MP camera. Have you ever stopped to think what makes it better? More pixels means better pictures. Why exactly is that? Continue reading “Understanding Camera Resolution”
Perpetual Enigma 