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Comment by michaelt | Hacker News Reader

Many image sensors have a 'windowed readout' function that lets you throw away lots of pixels' data, in exchange for a higher framerate.

So for example, a sensor that 1920px × 1080px × 30fps has the ability to output 62,208,000 px/second - and with the same ADC and MIPI bus, halving the number of pixels can double the number of frames per second.

You'll note this article's demo, 640px × 65px × 660fps = 27,456,000 px/second. So you might plausibly get it a bit larger - maybe 640×120 - but you're not going to get HD resolution at this framerate using this hardware.

(Obviously, there's also questions like exposure time and light levels so it's not quite as simple as I just made it sound)

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I'm mostly confused by the low vertical resolution. Would something like 320x240 work?

No. The camera image is read row-wise. One could perhaps stitch together the output of multiple cameras and RPis though differing perspectives may make this impractical under some circumstances.

This depends on the design of the sensor.

Basic sensors effectively have one analogue to digital convertor (ADC) per column of pixels. That would mean that if you wanted to reduce the horizontal resolution, you would be disabling some ADC's, which in turn would reduce how many pixels can be converted per second, giving you no benefit.

Would it be possible to buy a second camera and wire up its ADCs to the sensors on the first camera and then read the next set of vertical pixels? Effectively doubling the vertical resolution?

Yes, you can do 320x240 with modified raspiraw parameters. But you will get the same framerate as for 640x240, for v1 as well as for v2 camera.

You can do the opposite and increase horizonatal resolution for line scanner type of application with still impressive framerates:

"v2 camera can do 3280x32@720fps and 3280x64@500fps with frame skip rate less than 1% (tools attached)."

https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=1091...

You can do quite impressive gobal external shutter capturings (with v1 camera only!), eg. capturing a 109m/s airgun pellet in flight on a single multiple exposure frame 10x: https://github.com/Hermann-SW/Raspberry_v1_camera_global_ext...

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