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2bit Astrophotography with the Game Boy Camera

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Re: 2bit Astrophotography with the Game Boy Camera

#41

Post by rocky1138 »

jacquesm wrote: post #11
rocky1138 wrote: post #10

Earlier quoted context omitted.

Can you explain what you mean?

To make an image you need two axis, one horizontal, one vertical. Because the earth is already moving if you have a single photodiode looking at the stars you will scan a line if you wait a while. By adding a second axis of motion such as a speaker which you modulate with a saw-tooth curve you can add a second axis. If you then scan over time you can re-constitute the image by plotting the dots with the intensity cap…

I get that. I guess I was just confused as to why your first thought was to use a speaker to move the photo diode as opposed to an Arduino with a stepper motor.

Re: 2bit Astrophotography with the Game Boy Camera

#42

Post by monochromatic »

rocky1138 wrote: post #41
jacquesm wrote: post #11

Earlier quoted context omitted.

To make an image you need two axis, one horizontal, one vertical. Because the earth is already moving if you have a single photodiode looking at the stars you will scan a line if you wait a while. By adding a second axis of motion such as a speaker which you modulate with a saw-tooth curve you can add a second axis. If you then scan over time you can re-constitute the image by plotting the dots with the intensity cap…

I get that. I guess I was just confused as to why your first thought was to use a speaker to move the photo diode as opposed to an Arduino with a stepper motor.

It's an exercise in simplicity. Adding an Arduino is a little against the spirit.

Re: 2bit Astrophotography with the Game Boy Camera

#43

Post by userbinator »

joshumax wrote: post #39
objclxt wrote: post #9

Earlier quoted context omitted.

Yep, here's the technical data sheet for the chip: https://people.ece.cornell.edu/land/courses/ece4760/FinalPro...

Looks like the maximum supported exposure time is ~1 second... That mixed with the fact that the fact that it has a fairly shallow well depth probably means that the CMOS would be best suited for LUCKY imaging. Also adding a cooler to the back of the Gameboy camera may help reduce amp glow. Anyone have the specs on the ADC chip?

There is some reverse-engineered documentation here:

https://github.com/AntonioND/gbcam-rev-engineer/tree/master/...

The ADC appears to be part of the ASIC which contains most of the circuitry to interface the sensor to the GB.

Re: 2bit Astrophotography with the Game Boy Camera

#44

Post by averagewall »

Jyaif wrote: post #6

I doubt the CMOS is only 2 bits, otherwise we wouldn't have such nice dithering pattern. Somewhere in RAM there's probably at one point a representation of the image with at least 3 bits per pixel.

It's an analog output. You can very easily add an ADC to get higher bits per pixel and bypass the whole digital Gameboy interface. I did this once when the game boy camera was about the cheapest digital camera available. I even converted it to color by taking successive photos with colored filters and combining them in software.

Curiously, the camera has hardware edge detection which might have helped with very early machine vision.

Re: 2bit Astrophotography with the Game Boy Camera

#45

Post by kqr »

anfractuosity wrote: post #33
joshvm wrote: post #30

Earlier quoted context omitted.

Bin the image from a raspberry pi camera by a factor of.. 8 or so (maybe 16 if you need smaller)? Load the image as grayscale and divide the counts by 64 to get 2-bit values. Kinda difficult to buy crappy low resolution detectors these days because nobody makes them and you'd need to build the readout electronics yourself. You might as well just use a decent detector and make it look bad.

You can also interestingly get the raw sensor data from the Pi camera too, as in before the demosaicing is applied. I wonder, this may be silly, but could you not potentially get a slightly higher resolution image, if you just created a pixel for every sensel. Than if you were to apply the demosaicing algorithm then convert to grayscale.

> I wonder, this may be silly, but could you not potentially get a slightly higher resolution image, if you just created a pixel for every sensel. Than if you were to apply the demosaicing algorithm then convert to grayscale.

That's along the lines of what the Leica Monochrom promises. One drawback of doing it with a regular Bayer sensor is that the colour filters eat light, so while the number of pixels will increase significantly, the spatial resolution may not be that much better.

Re: 2bit Astrophotography with the Game Boy Camera

#46

Post by anfractuosity »

kqr wrote: post #45
anfractuosity wrote: post #33

Earlier quoted context omitted.

You can also interestingly get the raw sensor data from the Pi camera too, as in before the demosaicing is applied. I wonder, this may be silly, but could you not potentially get a slightly higher resolution image, if you just created a pixel for every sensel. Than if you were to apply the demosaicing algorithm then convert to grayscale.

> I wonder, this may be silly, but could you not potentially get a slightly higher resolution image, if you just created a pixel for every sensel. Than if you were to apply the demosaicing algorithm then convert to grayscale. That's along the lines of what the Leica Monochrom promises. One drawback of doing it with a regular Bayer sensor is that the colour filters eat light, so while the number of pixels will increas…

Cheers, that Leica looks very cool.

I just had a little play with the raw data from the Pi camera yesterday using the excellent PiCamera lib.

Re: 2bit Astrophotography with the Game Boy Camera

#47

Post by jacquesm »

zkms wrote: post #26
jacquesm wrote: post #11

Earlier quoted context omitted.

To make an image you need two axis, one horizontal, one vertical. Because the earth is already moving if you have a single photodiode looking at the stars you will scan a line if you wait a while. By adding a second axis of motion such as a speaker which you modulate with a saw-tooth curve you can add a second axis. If you then scan over time you can re-constitute the image by plotting the dots with the intensity cap…

Now you're thinking with superresolution!

Oh, I just had an even nicer idea that I really will have to try. I won't say what it is yet to not spoil the surprise but I'm sure that it will work :)

Re: 2bit Astrophotography with the Game Boy Camera

#48

Post by madaxe_again »

keithpeter wrote: post #16
anfractuosity wrote: post #14

Earlier quoted context omitted.

Could you explain in laymans terms how that would work? If you're only obtaining a single value for a single pixel and there's no movement, how does the pixel value change even if there's a grating in front? Or do you mean the grating can still move?

And noise? I used to do long exposure photos of interiors of buildings on film (~2h) but digital cameras seem challenged to me.

That's why most actual astrophotography is done with peltier cooled CCDs - firstly a lower temperature means less noise, but more importantly more consistent noise. You can then shoot dark, bias and flat frames, respectively average those, then subtract them from your stacked (averaged using any number of algorithms) light frames.

No reason it couldn't be applied to regular long exposure photography using a DSLR, either.

Re: 2bit Astrophotography with the Game Boy Camera

#49

Post by keithpeter »

anfractuosity wrote: post #34
keithpeter wrote: post #31

Earlier quoted context omitted.

125 asa FP4 roll film (all monochrome and hand developed needless to say, I used a Rollieflex camera on a tripod when I was playing with this stuff decades ago). I found the correction chart below on t'web [1] just now. I recollect using 2.5x per stop over 1 second which gives slightly longer exposures than [1], but then I did tend to 'pull' the development a bit (contrast goes up), so a 2 minute metered exposure wou…

That chart looks very interesting, thanks! Cheers, I'd be very curious to see your prints. I've just had a little look on google images at some of Edwin Smith's photos, they look stunning! The light in the photos look amazing. I still have an old Pentax K1000 film camera I think it is, I'll have to dig it out again some time :) I'd really like to get a medium format camera, but they're still not super cheap, I was lo…

Well I did say fantasy - a sheet of 10 x 8 film is the same cost as a roll of 35mm (similar area if you think of a contact sheet).

A 35mm camera on a tripod with shutter release would allow experimentation and allow you to decide about weight and carrying for hiking. I used the long exposures mainly in buildings in a city.

My images are not on Edwin Smith's level by any means, but the movement of the Sun direction over an hour does make a sort of smoothing of the light.

Re: 2bit Astrophotography with the Game Boy Camera

#50

Post by Frenchgeek »

orbital-decay wrote: post #12
jacquesm wrote: post #2

That's worthy of the term 'hack'. Very neat :) There should be some silly way of doing this with just a single photo diode and a speaker to provide one axis of motion and to let the Earth's rotation provide the other axis.

You can do this even without any motion and possibly even with no focusing optics, just with a single sensor, diffraction grating and a lot of math. This is called single-pixel imaging and is an ongoing research topic in computational imaging.

http://www.gperco.com/2014/10/single-pixel-camera.html
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