### Sometimes, Noise Helps

I’ve been working on a fun problem lately that involves estimating a scalar parameter from a set of repeated observations. It turns out that in certain circumstances, the presence of noise in the system can actually make the estimate more accurate, which is a little counterintuitive and also kind of cool. In my case, I…

### Transforms for Video Compression, Part 3: The DCT and Why Transforming Is Valuable

The use of transforms in data compression algorithms is at least 40 years old. The goal of this three-part series of posts is to provide the mathematical background necessary for understanding transforms and to explain why they are a valuable part of many compression algorithms. I’m focusing on video since that’s my particular interest. Part…

### Transforms for Video Compression, Part 2: Matrix Representation and 2D Transforms

The use of transforms in data compression algorithms is at least 40 years old. The goal of this three-part series of posts is to provide the mathematical background necessary for understanding transforms and to explain why they are a valuable part of many compression algorithms. I’m focusing on video since that’s my particular interest. Part…

### Cross-Processing Images in the Gimp

Color film photography looks to be fading fast; recently the last rolls of Kodachrome film were developed by the last place in the world that can process it. While black-and-white film development is commonly done in home laboratories, color film development requires specialized chemicals that were usually only available on an industrial scale. It appears…

### Transforms for Video Compression, Part 1: Vectors, the Dot Product and Orthonormal Bases

The use of transforms in data compression algorithms is at least 40 years old. The goal of this three-part series of posts is to provide the mathematical background necessary for understanding transforms and to explain why they are a valuable part of many compression algorithms. I’ll focus on video since that’s my particular interest. Part…

### Rolling CMOS Shutters and Curved Wiper Blades

One time last winter I shot a photo with my camera phone out the windshield of my car and got a strange image with curved wiper blades: No, my wipers don’t look like this! I’ve been meaning to track down the reason why this happened. It is clear that cellphone cameras don’t usually use mechanical…

### Creating the Orton Effect in Gimp

Recently I decided to learn how to write scripts in the Gimp image-editing program to automate certain tasks. The first task I wanted to automate was the Orton effect. This is an effect invented by Michael Orton in the 1990s, which consists of taking two copies of an image, one blurred, and one sharp, and…

### The Basics of 3D Image Acquisition

One of our clients is heavily involved in 3D video and has been for several years. However, several are just now starting to think about it because of the uptick of interest in the consumer electronics world. Enough questions have been posed to us recently that it seemed worthwhile to me to pull together a…

### Detecting Well-Focused Images

Recently, one of my colleagues mentioned to me that he takes large numbers of pictures and wanted to write a program to automatically determine which was in the best focus, out of a group of pictures that were taken of the same scene. He mentioned that he expected the algorithm to be computationally intensive. My…