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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."
BTW, that blank before the 'm' after the sensel size was the special 'u' used for microns; Slashdot's lame filtering cut it out. Sorry.
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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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1. Small phyiscal size (I wanna slip it in my pocket).
3. Good telephoto lens.
I think those two are mutually exclusive.
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We are the United States Government! We don't do that sort of thing.
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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You need to learn to pre-focus the camera by pressing the shutter half way down and waiting for the right moment before clicking through. Or set the camera to infinite focus by default so that you can grab and shoot at a moments notice.
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Just as a tip, I have found that the 50D's noise drops *dramatically* if you expose for +1 Ev (RAW) and then in post, pull back -1 to -1.5 Ev. There are lots more bits of resolution available in the stops as you move to the right (each stop has twice as many levels as the darker one to its left), and this gives the camera a one stop noise advantage over the way Canon hands it to us.
Canon seems to think we need a full stop of headroom in dynamic range over the brightest spot in the image being taken... that's simply not the case unless you're going to be compositing something brighter into the image. Seriously, try it. That +1 Ev will push noise down to an amazing degree, especially at ISO 3200 and below, where the 50D's banding issues don't rear their ugly little heads.
Of course, you can do the same with your 40D, and get even better results there, too. :)
This picture was shot at +1 Ev, ISO 100, with the 50D, and then recovered by pulling -1 Ev, effectively using the sensor 1 stop to the right. Check out the original size version ("All Sizes" button over the sample image) and look for noise in the shadows, or the sky (both the 40D and 50D are notorious for noise in blue skies... blue channel in the sensor is a weak link.)
Just be careful with your metering. If the camera isn't allowed to meter the brightest object in the portion of the scene you want to capture, you're going to clip the highlights and they will be unrecoverable.
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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.
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.
That would be going from 4mp to 16mp. Going from 4 to 8mp should only double your image size on disk.
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Akira Watanabe is playing self-serving marketing games. It is not about any particular number of megapixels, it is about the size of the light well of each pixel, or "pixel density" if you will. That determines the dynamic range and sharpness per pixel. Mr. Watanabe's company has pushed that past their main competitors despite the fact that those competitors have larger number of megapixels in their top cameras. How is it possible? Sensor size. Let's look at some of the offerings today on the market (the smaller the density the better):
So yes, Olympus is now hitting 5+ MP/cm2 on their SLRs despite having much lower number of pixels than Canon with their 5DMkII, Sony A900, or Nikon D3X. This is because Olympus boxed themselves into a smaller sensor (4/3). All the posturing about how 12MP is enough is only designed to hide their shortsightedness.
(BTW, /. seriously needs to allow <pre> tags)
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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.
JPEG compression is JPEG compression and RAW data is RAW data.
not really, there is actually lossless compression of jpeg images that will reduce size by 25% (sometimes more) from what a camera produces (not even including the removal of exif, and thumbnail removal)
You miss the point of RAW. RAW has more information than JPEG, because RAW is essentially direct dump from sensor + actual image settings. Sensors are not precisely RGB. But dumbly converting them to JPEG or PNG, you loose lots of information.
Classical example is balance of white. In JPEG/PNG it is all already pixels. In RAW you can change WB without loss of quality. Or extra bits of color, which can be used for EV (exposure value) adjustments.
It would depend on how much memory/CPU time/power the camera is willing to use. I find I get a much much better, and similar sized image post processing on my PC, than selecting at the camera. (IE minimal jpeg compression at the camera produces a larger, and noticeably worse image, than doing the downsize with imagemagic, from a full size RAW format on a PC)
ImageMagic isn't a RAW development tool.
If you want something on cheap, try RawTherapee or GIMP+dcraw (on Linux; GIMP + UFRAW on Windows). With GIMP/dcraw, you would be able to adjust RAW parameters ("develop a RAW") during import and then in GIMP do whatever you like with result of development.
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