Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Unbounded High Dynamic Range Photography Using a Modulo Camera

media.mit.edu

Post reply on HN
Print view View original

91–98 of 98 posts

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#91

Post by vernie »

oppositelock wrote: post #78
vernie wrote: post #76

Can somebody explain how this design differs from existing self-resetting pixel designs?

I'm not sure what you mean by self resetting pixel designs. Do you perhaps means the self-shuttering (rolling shutters) on CMOS sensors? This is very different. If you oversaturate either a self shuttering sensor or a shuttered CCD, that information is gone. All you know is that this is "100% bright, or more". Your software which turns raw sensor readings into an image makes the area full brightness, and you get blow…

I've seen CMOS pixel designs in the past that can detect saturation and effectively dump the well (reset) repeatedly until saturation no longer occurs.

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#92

Post by noobermin »

coldtea wrote: post #69
Tloewald wrote: post #41

Earlier quoted context omitted.

> This is a "computer scientists" understanding of photography, and this phrase alone can even be seen as "dangerous" by photographers. The actual headline of the article is actually more informative and less misleading than the subhead: "Unbounded High Dynamic Range Photography Using a Modulo Camera" In photographer's terms, they're referring to ending blown highlights (caused by filling the wells in a sensel) not s…

> BTW: assuming they can do this stuff, they presumably can read the sensor pretty darn fast What's funny is that the iPhone (and a high end Android phone) has way faster processors than your typical $10.000 DSLR.

You might be conflating cpu processor speed with, what is essentially "io" (light as an input, I'd suppose) and basically waiting for physics to happen.

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#93

Post by kuschku »

pto0239hn wrote: post #86
kuschku wrote: post #81

Earlier quoted context omitted.

Well, that ghosting effect is also called motion blur. If I integrate continuously, that is.

Motion blur, but different parts of the image would be exposed differently due to the nature of HDR, resulting in an odd look. Imagine instead of a runner, that you're panning from a dark to light scene.

Not necessarily.

Assume we say an 8-bit image is taken every 0.1 second, if I merge 4 of them, wouldn’t I just get a 10-bit image with 0.4 second shutter time?

Because I essentially just take the RAW image, load them into a 10-bit colorspace, add them up, and then store the image.

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#94

Post by ScottBurson »

Tloewald wrote: post #41
dr_zoidberg wrote: post #10

> No more will photographers or even ordinary people have to fumble with aperture size and exposure length. This is a "computer scientists" understanding of photography, and this phrase alone can even be seen as "dangerous" by photographers. There's more to aperture size and exposure length than "how much light reaches the sensor", like focus, depth of field, motion blur and bokeh, to name a few, that is not aknowled…

> This is a "computer scientists" understanding of photography, and this phrase alone can even be seen as "dangerous" by photographers. The actual headline of the article is actually more informative and less misleading than the subhead: "Unbounded High Dynamic Range Photography Using a Modulo Camera" In photographer's terms, they're referring to ending blown highlights (caused by filling the wells in a sensel) not s…

Consider that writing to a DRAM cell -- which involves charging or discharging a capacitor -- takes a few nanoseconds. This is at least four orders of magnitude faster than your estimate of 100µs.

I don't think it's a problem.

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#95

Post by darkmighty »

dharma1 wrote: post #67
darkmighty wrote: post #21

Earlier quoted context omitted.

Halos are a problem, but they can mostly be removed with good post-processing. Note they're not a fundamental aspect of tone mapping. Tone mapping is just whatever algorithm you chose to compress the HDR information into a low dynamic range we have for displays. The great thing about this camera compared to multi-exposure HDR (apart from the halo effect you mentioned) is you can actually take pictures of moving objec…

You can actually already do this with current cameras, using 2 exposures per frame, works for most types of action. Red Epic does this with HDR-X and hacked Canon cameras with Magic Lantern with Dual ISO

As explained in the article, this is different to combining exposures, which is what conventional HDR does too. The important thing to consider here is how does this scheme affect the SNR of the sensor. This scheme encourages keeping essentially maximum possible sensitivity (ISO), but this "modulo sensor" circuit may introduce some additional noise.

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#96

Post by darkmighty »

soylentcola wrote: post #77
darkmighty wrote: post #21

Earlier quoted context omitted.

Halos are a problem, but they can mostly be removed with good post-processing. Note they're not a fundamental aspect of tone mapping. Tone mapping is just whatever algorithm you chose to compress the HDR information into a low dynamic range we have for displays. The great thing about this camera compared to multi-exposure HDR (apart from the halo effect you mentioned) is you can actually take pictures of moving objec…

Out of curiosity, with regard to video, what would be the difference between what you describe and a nicer version of the sort of processing used in (for example) some Axis security cameras? I guess the current method is just to capture a decent range and then process each frame to boost the gain on shadows and lower the gain on highlights, right? Sort of an extension of quick-and-dirty HDR on still photos. Either wa…

I'm not familiar with those cameras. But if they're using a conventional sensor, this technique yields qualitatively different results.

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#97

Post by gohansan »

paulmd wrote: post #59
Tloewald wrote: post #57

Earlier quoted context omitted.

All good points. (And my figure actually assumes 10x faster and no loss of time between clearing wells and capturing photons -- i.e. 90% of time is spent capturing photons and 10% is spent clearing the well with no downtime -- to be generous. And, again, just to equal current performance.) The underlying idea is sound -- storing bits is a linear problem but storing photons is an exponential problem. Of course you're…

Yeah I was thinking that too. No matter how tiny a capacitor, you have (tens of) millions of them on the sensor, one per photoreceptor, and you're charging and discharging them 100k-10M times per second. That's a lot of energy being accumulated and dissipated right next to the photoreceptors. Thermal noise is gonna be nuts on a modulus sensor, too. No system is ever unbounded, period, unless you live in a world of fr…

maybe that energy can be used to recharge the battery

Re: Unbounded High Dynamic Range Photography Using a Modulo Camera

#98

Post by eru »

Tloewald wrote: post #41
dr_zoidberg wrote: post #10

> No more will photographers or even ordinary people have to fumble with aperture size and exposure length. This is a "computer scientists" understanding of photography, and this phrase alone can even be seen as "dangerous" by photographers. There's more to aperture size and exposure length than "how much light reaches the sensor", like focus, depth of field, motion blur and bokeh, to name a few, that is not aknowled…

> This is a "computer scientists" understanding of photography, and this phrase alone can even be seen as "dangerous" by photographers. The actual headline of the article is actually more informative and less misleading than the subhead: "Unbounded High Dynamic Range Photography Using a Modulo Camera" In photographer's terms, they're referring to ending blown highlights (caused by filling the wells in a sensel) not s…

They don't count resets. They recover the number of resets via clever post processing.
Post reply on HN