Wednesday, February 08, 2012

#CHIPS: "Smarter Cameras Plumb Composition"

A rose is a rose if its red and round, but smarter cameras can now tell the difference between a real rose and a silk rose using chemical composition analytics.

Imec’s smarter camera makes use of a hyper-spectral sensor that not only senses color and brightness, but also perceives an object’s chemical composition.

A new type of smarter camera can take a picture but also assess the chemical composition of the objects being imaged. This enables automated inspection systems to discern details that would be missed by conventional cameras.

Cameras usually record the color and brightness of an object with a two-dimensional array of semiconductor photoreceptors, resulting in a megapixel map that looks like a conventional photo. Unfortunately, closely spaced objects of the same color are often hard to discern. 3D cameras can separate similarly colored objects that are at different distances, but if they are closely packed on the same plane, even 3D cameras can be fooled. A smarter camera from the Interuniversity Microelectronics Centre (Imec, Leuven, Belgium) promises to solve this problem, by simultaneously performing chemical composition analytics.

Last month at the international Society of Photo-optical Instrumentation Engineers (SPIE), Imec showed its hyper-spectral camera for the first time. This smarter camera can not only perceive the shapes of objects, but also their chemical composition, which is useful for all sorts of auto-inspection systems, such as crop screening analytics, ascertaining food spoilage, skin-cancer detection, and military-target selection.

Imec's smarter camera is based on a low-cost semiconductor chip technology that combines traditional imaging techniques with hyper-spectral sensors that respond differently to objects with different chemical compositions. The system-on-chip (SoC) solution can accurately distinguish between objects that appear virtually identical using traditional red-green-blue imaging chips.
Hyper-spectral cameras themselves are not new, but unfortunately the units have typically been large, expensive, and slow operating. This limited their use to special-purpose research applications. Imec's SoC implementation, on the other hand, remedies these shortcomings, allowing their use in cost-sensitive, time-critical, and high-throughput applications.

The technique by which Imec fabricates its smarter camera SoC is fully compatible with the conventional complementary metal-oxide semiconductor (CMOS) process technologies with which nearly all processors and memory chips are made today. This enables the smarter cameras to be easily mass produced. By adding special spectral filters to a traditional CMOS image sensor across an 8-inch CMOS wafer, thousands of smarter camera SoCs can be simultaneously fabricated at extremely low prices.

The demonstration smarter camera shown at SPIE had four million pixels and could operate at a rate of 180 frames per second (FPS, equivalent to over 2000 lines-per-second, with 500 FPS planned) for use in both high-resolution and high-throughput applications. The hyper-spectral filters measured chemical composition in 100 spectral bands between 560-to-1000 nanometers, with a transmission efficiency of 85 percent.