Histogram Equalization Of RGB Images

contrastWhen you capture an image using your phone in the evening without flash, do you see how the image is a bit on the darker side? When you take an image with too many lights around you, the images becomes a bit too bright. Neither of the two situations gives us a good quality picture. The human eye likes contrast in images. What it means it that the bright regions should be really bright and the dark regions should be really dark. Almost all the apps and services you use today include this functionality, at least the good ones do. So how do we take one of these dark (or bright) images and improve its quality?   Continue reading

Content Delivery Network – Part 2/2

mainIn the previous post, we discussed about content delivery network (CDN) and why we need it. This post is a continuation of that topic. Here, we will discuss about the pros and cons of using CDN. CDN obviously helps the sites that experience heavy traffic. Most of the times, you will think that just using a CDN will deliver a better performance, but this is not always the case. If you don’t choose your provider carefully, your site will end up suffering. Let’s look at some of the advantages and disadvantages of using CDN.   Continue reading

Content Delivery Network – Part 1/2

mainInternet users today are demanding faster and higher-quality services from their media hosting companies. Being an internet user yourself, you should know that we place a high demand on these services. This is the reason quick access and delivery of rich-media like music, photos, videos etc has become a top priority. Wait a minute, why we need to care about all that? Doesn’t that just happen somewhere on the server? Well, who do you think makes that happen? It’s the people who manage the website. The beautiful site that loads all the high-resolution images for you doesn’t just work magically by itself. It needs to be optimized in a zillion ways for you to not feel the pain. All of your pages, including your photos and videos, will load quickly and instantly if the website owners use the right Content Delivery Network (CDN). Let’s see what this whole thing is about, shall we?   Continue reading

Purkinje Effect

mainEver wondered why the colors seem to change at night? For example, if you look at an air painting, you can see how the colors of objects look radically different in very low light just before dawn or dusk. Consider a red rose, for instance. We know that the flower’s petals are bright red against the green of the leaves in daylight. But, take a look at dusk and you will see that suddenly the contrast is reversed, with the red flower petals now appearing dark red or dark warm gray, and the leaves appearing relatively bright. Bright red doesn’t remain bright red anymore, and green doesn’t remain green either. They all become a bit monochromatic and it becomes difficult to separate them. Why does this happen?   Continue reading

Kruithof Curve

mainThis is more of a continuation of my blog post on color temperature. Back when fluorescent light sources first came up, they changed the way humans thought about light and color rendering. A scientist named Arie Andries Kruithof performed some experiments on how the human eye relates the amount of light in a given time of day to the color temperature of the light source, and came up with a theory. As we move through the day, the amount of light we get keeps varying. Typically, human beings like higher color temperature light sources during the daytime hours, and lower color temperature sources once the sun goes down. People in warmer climates tend to favor cooler color temperature sources, and people in colder climates like warmer light. So what does this have to do with the Kruithof curve?   Continue reading

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

How To Set The Background Image For Your iOS App?

When you are designing your iOS app, you cant help but think about the aesthetics. You want to present your app in the best possible way. There are some things you cant ignore, like the icon, or the background, or the first screen. These are the things that tend to impact your app the most. Although the functionality is the most important part, a new user will not get there if you don’t make your app look aesthetically pleasing. A new user doesn’t know what your app does, so you should give the user a strong reason to keep going. The background image is one of the key aspects in your app. There are two ways of setting the background image.   Continue reading


mainPixelation is the display of a digitized image where the individual pixels are easily visible to a viewer. This can happen unintentionally when a low-resolution image designed for an ordinary computer display is projected on a large screen. In this situation, each pixel becomes separately viewable. It’s not pretty! Pixelation is also sometimes used to describe the act of turning a printed image into a digitized image file. As the image is captured, it is processed into a vectorized or rasterized file that can be used to illuminate color units (called pixels) on a display surface. So why does it happen? What exactly happens in there?   Continue reading

Graph-Cuts In Computer Vision

mainThe theory of graph-cuts is used often in the field of computer vision. Graph-cuts are employed to efficiently solve a wide variety of computer vision problems, such as image smoothing, the stereo correspondence, and many other problems that can be formulated in terms of energy minimization. Hold on, energy minimization? It basically refers to finding the equilibrium state. We will talk more about it soon. Many computer vision algorithms involve transforming a given problem into a graph and cutting that graph in the best way. When we say “graph-cuts”, we are specifically referring to the models which use a max-flow/min-cut optimization. Too much jargon? Let’s just dissect it and see what’s inside, shall we?   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