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So can LED screens be used as a camera?

immibis 2y ago
No. Even if each LED was a good light sensor (it's not good) the control circuitry is output-only. And you need a lens, or else every pixel receives the light from all around it, and reads just the average brightness of the room.
dragontamer 2y ago
The "D" in LED is "Diode", commonly referring to the "P-N Junction" and its capabilities. A CMOS sensor is an array of thousands of photodiodes. So erm... diodes are _already_ used as the basis of modern digital cameras. I guess building one out of LEDs (diodes designed to emit light, rather than receive it) is feasible but I can't imagine it'd work very well. If you build a big enough camera and calculate the right lenses, it probably would work. But it wouldn't surprise me if the proper size of such a camera was on the order of a 20-feet by 30-foot room (with a "camera sensor" the size of maybe 5-feet by 5-feet, composed of thousands of LEDs acting as terrible photodiodes). -------- A proper CMOS sensor miniturizes all of that to happen on a micrometer scale, so you can shrink modern cameras down to... well... the size of our phones. But the principles of light, sensors, and cameras in general work even with larger / inefficient objects. You just got to build a "large enough" camera to compensate for all the problems. EDIT: And also what the other poster pointed out about the control circuitry. The circuits in a typical LED Screen are all "output only". There's no way for the information to come back / reverse the LED Screen because the circuits are already set. I'm assuming you're somehow building those circuits and have embedded them into the LEDs somehow.
- nialv7 2y ago
  hmm, can I use a digital camera sensor as screen then?
  - londons_explore 2y ago
    You would have to rewire the sensor internally, which considering it's a silicon chip ain't gonna happen. Also, it would be an infrared screen.
Zenst 2y ago
Yes, if you just want to record shadow puppets. https://en.wikipedia.org/wiki/Shadow_play https://en.wikipedia.org/wiki/Shadow_play

No. Even if each LED was a good light sensor (it's not good) the control circuitry is output-only. And you need a lens, or else every pixel receives the light from all around it, and reads just the average brightness of the room.

dragontamer 2y ago

The "D" in LED is "Diode", commonly referring to the "P-N Junction" and its capabilities. A CMOS sensor is an array of thousands of photodiodes. So erm... diodes are _already_ used as the basis of modern digital cameras. I guess building one out of LEDs (diodes designed to emit light, rather than receive it) is feasible but I can't imagine it'd work very well. If you build a big enough camera and calculate the right lenses, it probably would work. But it wouldn't surprise me if the proper size of such a camera was on the order of a 20-feet by 30-foot room (with a "camera sensor" the size of maybe 5-feet by 5-feet, composed of thousands of LEDs acting as terrible photodiodes). -------- A proper CMOS sensor miniturizes all of that to happen on a micrometer scale, so you can shrink modern cameras down to... well... the size of our phones. But the principles of light, sensors, and cameras in general work even with larger / inefficient objects. You just got to build a "large enough" camera to compensate for all the problems. EDIT: And also what the other poster pointed out about the control circuitry. The circuits in a typical LED Screen are all "output only". There's no way for the information to come back / reverse the LED Screen because the circuits are already set. I'm assuming you're somehow building those circuits and have embedded them into the LEDs somehow.

nialv7 2y ago
hmm, can I use a digital camera sensor as screen then?
- londons_explore 2y ago
  You would have to rewire the sensor internally, which considering it's a silicon chip ain't gonna happen. Also, it would be an infrared screen.

Zenst 2y ago

Yes, if you just want to record shadow puppets. https://en.wikipedia.org/wiki/Shadow_play https://en.wikipedia.org/wiki/Shadow_play