3 ms·

Lots of consumer cameras have near infrared sensitivity, mostly 750nm but with a long exposure I can get photographs through a 900nm filter in my Fuji X-Pro. Y

Lots of consumer cameras have near infrared sensitivity, mostly 750nm but with a long exposure I can get photographs through a 900nm filter in my Fuji X-Pro. You lose at least four stops. Could the photography technique work to determine ripeness? Assuming the fruit is fairly motionless of course.

hobofan 3y ago
I have to admit I'm not the biggest expert on it. I mainly know about it because my brother wrote his PhD thesis about using portable Vis/NIR spectrometers as food checkers (verifying that they perform on par with expensive desktop spectrometers). He showed me the SCiO in person a few times, and IIRC always had to make direct contact with the solid probe, so I'd be surprised if a NIR photograph would be a suitable substitute. I think it also mainly measures the area of the fruit where you make contact, so to get an optimal picture about the ripeness of a single fruit it's good to take multiple measurements. That also usually makes fruits with tick skins/shells (e.g. melons) hard to measure. There seems to be a startup[0] aiming to bring suitable sensors to smartphones so that anyone has access to it - something that the food checker research literature has been hinting at for some time. [0]: https://mantispectra.com https://mantispectra.com
- gorgoiler 3y ago
  Thinking about it a little more, it might have some mileage. The IR spectrometer is just measuring the color of the avocado, albeit very precisely and under known lighting conditions. One of the reasons photographers enjoy infrared photography¹ is because foliage shows up brilliant white against pitch black² skies³. Photosynthesis is inhibited by both green and IR light so plants are bright in IR for the same reason our eyes see it as green. I absolutely think that you could get the same result with a flash photograph from a good modern camera and probably just using the green channel. One of the many things these cameras are designed to be good at is detecting minute subtleties in shades of green⁴. I’m looking forward to trying it on the weekend. ― 1. Traditionally done with a monochromatic black and white film where only deep, bright reds gave the negative any density, rendering as brightness in a positive print. This is in contrast to “panchro” black and white where a bright object of any color would print as white. 2. Unlike blue light, the atmosphere disperses almost no infrared. 3. A good example of all of the above is here: https://fineartamerica.com/featured/infrared-willow-tree-study-rich-stedman.html https://fineartamerica.com/featured/infrared-willow-tree-stu... 4. Our eye’s sensitive to green is partly why digital cameras have twice as many green sensors as they do red and blue. It’s also why high fidelity inkjet printers use more shades of ink for printing photographs. (Epson printers use one yellow, two different cyans, and three different magentas.)

hobofan 3y ago

I have to admit I'm not the biggest expert on it. I mainly know about it because my brother wrote his PhD thesis about using portable Vis/NIR spectrometers as food checkers (verifying that they perform on par with expensive desktop spectrometers). He showed me the SCiO in person a few times, and IIRC always had to make direct contact with the solid probe, so I'd be surprised if a NIR photograph would be a suitable substitute. I think it also mainly measures the area of the fruit where you make contact, so to get an optimal picture about the ripeness of a single fruit it's good to take multiple measurements. That also usually makes fruits with tick skins/shells (e.g. melons) hard to measure. There seems to be a startup[0] aiming to bring suitable sensors to smartphones so that anyone has access to it - something that the food checker research literature has been hinting at for some time. [0]: https://mantispectra.com https://mantispectra.com

gorgoiler 3y ago
Thinking about it a little more, it might have some mileage. The IR spectrometer is just measuring the color of the avocado, albeit very precisely and under known lighting conditions. One of the reasons photographers enjoy infrared photography¹ is because foliage shows up brilliant white against pitch black² skies³. Photosynthesis is inhibited by both green and IR light so plants are bright in IR for the same reason our eyes see it as green. I absolutely think that you could get the same result with a flash photograph from a good modern camera and probably just using the green channel. One of the many things these cameras are designed to be good at is detecting minute subtleties in shades of green⁴. I’m looking forward to trying it on the weekend. ― 1. Traditionally done with a monochromatic black and white film where only deep, bright reds gave the negative any density, rendering as brightness in a positive print. This is in contrast to “panchro” black and white where a bright object of any color would print as white. 2. Unlike blue light, the atmosphere disperses almost no infrared. 3. A good example of all of the above is here: https://fineartamerica.com/featured/infrared-willow-tree-study-rich-stedman.html https://fineartamerica.com/featured/infrared-willow-tree-stu... 4. Our eye’s sensitive to green is partly why digital cameras have twice as many green sensors as they do red and blue. It’s also why high fidelity inkjet printers use more shades of ink for printing photographs. (Epson printers use one yellow, two different cyans, and three different magentas.)