A very high resolution binary sensor

I've been reading this article from EPFL, about a new kind of imaging sensor. Each pixel, or photodetector, measures the light by producing a binary value of either 0 or 1. So, each pixel is, loosely speaking, a photon counter. The advantage of this sensor is that it has the potential to be really fast (high frame rate). Once such binary data is collected, a grayscale image can be obtained from it by applying image processing techniques. This is similar to what the eye does when it sees the spatial dithering in newspaper halftones.

RIP Bryce Bayer

Kodak researcher Bryce Bayer, who created the widely used Bayer filter, has died.

Digital microscope

I randomly came across digital microscopes, which are basically single lens devices that use the high resolution of the sensor (plus a large monitor) to give the impression of magnification. The concept is basically macro photography packaged as a kind of non-optical magnification. You can buy one for about $100. While I was initially skeptical, I learned about some of the challenges faced when building these devices. These include matching the single lens throughput with the sensor resolution and dealing with issues relating to lighting and frame rates. Here is a site with more details including some images of small objects. Some interesting trends include a publication that uses a second lens (an eyepiece) with a cellphone/tablet to enable low-cost lab applications. I also found an application where a company built a stereoscopic digital microscope and hooked it up to a stereoscopic TV. So you basically can see live 3D images of small objects, like an insect.

Antenna lens

The Economist has an interesting article about a new kind of lens made of tiny antennae. When light hits the antennae, the photos are absorbed before being re-emitted (retransmitted?) in a converging direction.

Broken push-broom

Thanks to E for this link, where it looks like an artist bought an expensive push-broom camera and broke its motor. The camera then keeps taking pictures along the same column. Stringing these together gives an interesting image: a static pushbroom projection of a moving world.

A cardinality sensor

Recently I was talking to Takeo Kanade, and he mentioned an old paper of his with Vladimir Brajovic, where the image produced by the sensor is sorted according to radiance. If two pixels receive the same light energy, then they get the same rank. Now you might think this is uninteresting, since you could just take a regular image and sort it in software. But remember, I said sorted by radiance (which is continuous), not intensity measurement (which is usually 0 - 255). For a scene that is over-exposed, with a regular sensor, you'd get an image that is mostly 255s. With the cardinality sensor, you'd get an image with lots of information, since it would preserve the rank of each scene point (which depends on the number of other scene points that are darker or brighter). Essentially each pixel is in a race to be overexposed, and once the pixel reaches the value 255, it increases a counter variable by 1 and takes the counter variable's value (which is its rank). Ties get the same value, but increase the counter variable by the number of tied pixels.

Random articles

Here are some articles I have been reading recently:

The latest update in the CMOS vs. CCD war.

What kind of sensors go on a Mars robot?

Hoping to print tons of micro-sensors in your garage? We are getting there.