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What to Fight Over After Megapixels?
NewScientist has a quick look at where the digital image crowd is headed now that the megapixel wars are drawing to a close. Looks like an emphasis on low-light performance and color accuracy in addition to fun software tools are the new hotness. "For years, consumers have been sold digital cameras largely on the basis of one number - the megapixels crammed onto its image sensor. But recently an industry bigwig admitted that squeezing in ever more resolution has become meaningless. Akira Watanabe, head of Olympus' SLR planning department, said that 12 megapixels is plenty for most photography purposes and that his company will henceforth be focusing on improving color accuracy and low-light performance."
Optical SVG - the ultimate! Forget pixels. Have cameras sketch accurate SVGs of a scene with the ability to show or print at any resolution.
Good luck with that one. It's a lot harder than it sounds. Try tracing a simple 2-color bitmap in Inkscape sometime and zoom in real close. Now try tracing a full-color, full page photograph in the maximum number of colors possible.
Oh, BTW, hope you got lots of RAM and time to wait....
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What about the Red Epic 617 that will deliver 261.4 megapixels at 30fps, that's supposed to be available for $53k next spring?
I had thought that Japan's 4320p HDTV (33 megapixels) cameras were nuts, but Red's sensors are pushing far far past that.
Cameras and displays are getting to the point that they push more data than any network we've built (and so are obviously many orders of magnitude faster than the human optic nerve).
The dynamic range of our linear sensors is the weakest part of the chain. Film sucks compared to modern digital in all ways except their response curve: many films don't capture light levels in a linear way, so they can discriminate details in the clouds in a bright sky even while capturing details in the shadows. Almost all digital sensors are on the order of 9~12 stops of acceptable dynamic range, and they've been there for nearly a decade.
Cameras tend to expose for the midrange automatically. To avoid blowing the highlights, which is very visible on a screen or printout of our photos, we have to artificially adjust that exposure, called "stopping down," until we capture details in the highlights, at the expense of detail in the shadows.
There are some combinatorial techniques to achieving high dynamic range; you take multiple exposures and mathematically or artistically mix them to achieve both shadow and highlight details. But this technique is not well suited to movies or still-shots of moving scenes.
Sensors need to get a LOT better at achieving a dynamic range of 20 stops or more.
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That is about 10^16 photons per square meter. Of you cram 10 MP on a 5x5 mm sensor, that is 3000 photons per pixel. Each pixel has a color filter that on the average transmits 25% of the photons, which means 750 photons per pixel. Simple Poisson statistics means that you get a noise that is 1/sqrt(3000) = 4% for these numbers. That is if the sensor has 100% effectivity and no electronic noise.
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Colors are always off. No two CCD brands are color calibrated in the same way. If you want accurate color, just shoot in RAW mode, then create or obtain reasonable color profiles for the camera and all your devices, at which point it's a non-issue. If your camera can't shoot in RAW, there's your problem.
As for low light response, the easiest way to get better low light response is to use bigger optics. The light gathering of optics is directly proportional to the area of the lens (the square of the radius of the lens). The big problem we have is that camera makers are trying to use progressively smaller lenses for easy portability, and that is directly contrary to the goal of improving low light response. They have to make huge strides in response just to break even.
Until the quest to keep making cameras smaller stops, the low light performance will continue to regress. It's basically unavoidable. At best, you could improve the noise response in low light by using Peltier junctions or something to cool the chip, but there goes your battery life.
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This is normal. When you double the resolution, you double it in 2 dimensions. (Height and Width) This results in a four-fold increase in data size.
But 4 megapixels to 8 megapixels isn't doubling the image size, it's doubling the number of pixels. So it is reasonable to expect the file size to double, not quadruple.
Poor light performance has ALWAYS been the biggest problem I've had with digital cameras. What good is a million megapixels when you can't even see your subject without shooting in direct sunlight? Low light performance has always lagged behind on digitals (most of them I've bought over the years have had the light performance of equivalent of about 200 ISO film).
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But putting anything above 10 megapixels in a tiny form factor is a total waste. I shoot with a Nikon D2x and D300 - both 12 megapixel cameras. With these cameras and decent lenses you need excellent shooting skills to really tax the quality of the file. That means fast shutter speeds and decent glass. Neither of which are common on the low end cameras. Even with a fairly fast shutter speed, say 1/200 with a 50 mm lens, you can often see visible differences between a hand held shot and one set up on a tripod. There is that much data in a 12 megapixel file. Of course, that is pixel peeping which most point and shoot camera users won't do.
Big files slow the camera down - more data to push through. Slower overall response. More battery used. Bigger files, harder to email. Not saying that the manufacturers won't try this, but it's pretty pointless. There are lots of other ways to improve picture quality - better high speed capability, stabilized lenses, better optics.
Faster! Faster! Faster would be better!
No, it is misunderstanding physics.
The more pixel sensors there are, the more space there will be between them relative to the total area. Increase the number of pixel sensors, and you reduce the area that's covered by sensors.
Take star photography as an example -- if the light from a star hits between two pixel sensors, it won't be registered. It's immensely better that it registers as a faint pixel with less accuracy than it not being registered at all.
Another example is low-light photography, where the base ISO decrease you get by increasing the pixel count leads to more artefacts and a worse result.
To always get a benefit from an increased amount of pixels here, you have to make sure that the amount of border between pixel sensors does NOT increase. But with current technology, it does.
This is, by the way, why I much prefer a Nikon D40 over a D40x. The cameras are near identical, except for the sensor, where the D40 has a 3008x2000 ISO-200 sensor, and the D40x has a 3872x2592 ISO-100 sensor. The D40 is the better camera to use for things like star photography or low light conditions, because a larger part of the D40x sensor is dead space.