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IR Eye

A cheap infrared scanner can replace an expensive thermal-imaging camera

5 min read
IR Eye

A recent energy audit at my place of worship indicated that the insulation in the walls and ceiling was pretty poor. That was obvious enough from casual inspection. But some subtle cracks revealed themselves only through the use of high technology—thermal imagery, which showed the locations of several air leaks in vivid detail.

Seeing those results, I was so impressed that I went off to the Web to check out thermal-imaging cameras, only to discover that they typically run several thousand dollars. Ouch. This type of imagery shouldn't be confused with run-of-the-mill infrared photography, which uses wavelengths only slightly longer than 0.75 micrometers or so. Thermal-imaging cameras sense much longer wavelengths, typically 8 µm or more.

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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