What Is Color Temperature?

mainWait a minute, isn’t “temperature” associated with weather? How can color have temperature? The thing is that color temperature is actually a characteristic of visible light that has several important applications in photography, publishing, and many other fields. We actually see and feel it all the time, it’s just that we don’t realize that we like certain color temperatures more than others. The concept of color is more easily apparent to us. We can see what’s red and what’s blue. There are a lot of characteristics of color that we feel, but don’t realize. So what exactly is color temperature?   Continue reading

The Intuition Behind Image Watermarking

mainThis 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

Image Steganography

mainAs 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

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

How Do We Recognize Objects?

Look around and you will see a lot of day to day objects. You recognize them almost instantaneously and involuntarily. You don’t have to wait for a few minutes after looking at a table to understand that it is in fact a table. Machines, on the other hand, find it very difficult to do this task. People have been working for decades to find a solution to this problem, but they have only been able to achieve an accuracy of around 65%. Why is it so hard for machines to recognize and categorize objects like humans? What’s so difficult here? We do it everyday and we get it right almost every single time. What’s the missing link? This is actually the holy grail of computer vision!   Continue reading

Peeking Into The Third Dimension With 3D Glasses

Instead of directly explaining it, I will take a different route this time. Let’s take a look at this conversation between Walter and Michael. In case you are not familiar with them, Walter is a mathematician and Michael is his friend who refuses to acknowledge that humans need complex mathematical models. This attitude of Michael doesn’t sit well with Walter and hence they are constantly at loggerheads over this issue. They were once walking along and they came across a multiplex.   Continue reading

Good Things Come In Small Packages

We encounter digital images everyday. We see a lot of JPEG files on our computers, cameras, phones and tablets. The actual images are huge and it should actually take up a lot of space to fit in all that data. But somehow our machines are able to compress all those images and store everything compactly. Ever wondered how it’s possible to fit so many images in such small space? How can the JPEG algorithm achieve so much reduction in size without visibly losing the image quality?   Continue reading