He speaks common sense against the paranoia of the crowd.
The point is to reduce crime, despite some small impact to privacy in public places, which was never a right or a necessity for 99% of the public to begin with!
Re:optical resolution is far more important
on
Beyond Megapixels
·
· Score: 1
You wrote: "Increase the signal, increase the noise (although not as much). The problems may seem to 'disappear' in higher light"
So then what physical phenomenon causes noise to increase with intensity?
The S/N ratio increases linearly with intensity because noise is constant, caused by thermal quantum effects. Processing noise is also constant. Each stage in the processing up to the analog to digital conversion adds a bit of noise, which again is constant for all intensities. Noise introduced by digital quantization is also constant for linear AtoD converters. Logarithmic AtoD quantization noise may increase slightly, though still much less than linearly.
I never said S/N isn't relevant. I said "sensitivity and CCD size may not matter". Big difference. Plenty of cheap cameras with horrible optics and cheap CMOS sensors (cheap webcams, pinhole cameras, etc) are highly insensitive under low light but can produce great images under strong lighting conditions. Try it sometime.
optical resolution is far more important
on
Beyond Megapixels
·
· Score: 3, Informative
The article is a bit misleading, and perhaps wrong. It exchanges one myth for another myth. Indeed megapixels alone do not define resolution. However, CCD size isn't the answer either!
The article fails to address the issue of optical resolution, i.e. lens quality and aperture. Does the number of pixels act as the resolution limiter, or does the quality or size of the lens limit resolution? Many consumer cameras use poor quality small lenses, but boast of large numbers of pixels. Since CCDs are cheap and good lenses aren't, why not over sample the image enough so the consumer thinks they're getting a superior image, and has to pay more for flash memory? The number of pixels can be irrelevant for a camera with a small or cheap lens. Larger aperture lenses will always resolve better, as is the case with all imaging optics anywhere in the spectrum between telescopes and microscopes. Cameras are no different.
The reason professional cameras are better is not just because the CCD is larger. A larger CCD demands a larger lens. That is the difference.
Furthermore, sensitivity and CCD size may not matter at all! The problem of noise for smaller pixels is only relevant when the camera is capturing lower intensity images. Brighter intensities overcome the noise. Larger aperture lenses also collect more light and resolve better, reducing noise and increasing contrast.
You wrote: "Your floor lamp does not put out anything close to 6500k light... Put your lamp bulb in a projector and you will have a projector that will be impossible to calibrate to any sort of decent color balance."
That isn't the issue either.
Flat panel fluorescent backlights and other technologies put out uniform light with great color balance. Furthermore, filters can be used to shape the source and adjust color balance.
The issue is the compactness (light source density) being high enough yet proportionately sized with respect to the projecting and condensing lenses and the LCD/DLP imaging element. A big projector can use a bigger, cheaper light bulb given the same desired screen size.
You wrote:
"Your floor lamp does not put out anything close to 6500k light... Put your lamp bulb in a projector and you will have a projector that will be impossible to calibrate to any sort of decent color balance."
That isn't the issue either. Flat panel fluorescent backlights and other technologies put out uniform light with great color balance. Furthermore, filters can be used to shape the source and adjust color balance.
The issue is the compactness (light source density) being high enough yet proportionately sized with respect to the projecting and condensing lenses and the LCD/DLP imaging element. A big projector can use a bigger, cheaper light bulb given the same desired screen size.
Why must projector bulbs be small, bright and expensive?
In short because the condenser lens (between the light source and LCD/DLP) is not big enough to handle a larger, less expensive light source.
Given size (cost) constraints on the LCD or DLP imaging element and projection and condensing lenses, a proportionately compact and bright source is required. This allows efficient coupling of the light source to the imaging element, achieving full filling of the focal plane (lens aperture) and maximum optical resolution at the projection screen. A larger light source with the same sized imaging element will require a bigger, more expensive condenser lens and mirror, possibly several additional large lenses. A spatial filter can also be used (like a pinhole camera) to boost resolution at the expense of wasted light and heat.
With size, weight and initial cost being the primary concerns, it isn't surprising that projectors ended up with highly consumable light sources.
If you replace the expensive bulbs with a cheaper bulb of the same size the picture will simply be dimmer, and at the same resolution.
You make some good points, but study after study after study have shown that long term investors make significantly more than short-term. It doesn't mean someone CAN'T make a ton of money doing short-term trades, but it IS fair to assume that one time frame is inherently more successful, because it has been proven to be so!
Most of the studies you refer to are based on the US market, not foreign markets. Indeed the US market has had a positive bias over the last 70 years. The average long term participant would have participated in this trend. However, many foreign stock markets (eg Japan) do not show long term upwards bias.
If it were not for a long-term upward bias in the US market, perhaps fewer investors would have bought into the market, further increasing stagnation. It's a self fulfilling prophecy. Furthermore, economic growth must keep pace with stock prices, otherwise valuations get out of control leading to a crash.
One can then argue that the last 70 years has provided unprecedented economic growth that may be hard to match over the next 70 years. Many sources of revenue and efficiency were taped. World economies changed from mostly agrarian to now encompass everything imaginable. Countless technologies were invented. The pace was quickened by WWII, the arms race and space race. Commodities, (and now jobs) move fluidly according to supply and demand. Countless jobs are being replaced by technology.
It's not clear that any of this will lead to economic (revenue) growth to allow stock prices to continue to trend higher. Look at the history of Japan's economy. We seem to be following them more or less. Unless we colonize the moon or mars, the future may more likely be economic stagnation.
Everyone realizes the offer is out of line. Some declare "free money!" and purchase as many as they can, then sell at $47, $52, $55, etc. None seem to realize that trades will be busted (canceled) until it's officially announced.
Stocks were never meant to be traded as speculation on the share price.
This is completely false. Investors would never purchase stock without the ability to sell it.
Purchasing stock is purchasing a share of a company's future earnings in the form of dividends.
Future earnings and dividends always have some uncertainty. Traders and investors trade or hold stock positions based on speculation on the future of earnings/dividends.
This is why people who invest long term make more than people who buy expecting to sell with a profit in the same week.
This is completely false. It is possible to be successful with both long term (investing style) and short term (trading style) speculation.
The key to low risk returns is to have a reliable, statistically valid method for speculation. Some find success with a long term fundamentals-based approach, others with exotic neural networks, or other higher frequency analysis. Some can achieve profitability with hundreds of trades per day. It is wrong to assume that any one time frame or bias (eg. long positions only) is inherently more successful.
There are several stocks paying 5-10% real returns as dividends right now.
That's because the stock price has dropped relative to the dividend, while the dividend has remained constant. What most don't realize is that these stock prices AND their dividends are at more risk than 5 to 10%. What good is a 10% annual dividend if the stock drops 25% in the first year?
Slashdot Mirror
Mod Parent UP!
He speaks common sense against the paranoia of the crowd.
The point is to reduce crime, despite some small impact to privacy in public places, which was never a right or a necessity for 99% of the public to begin with!
You wrote: "Increase the signal, increase the noise (although not as much). The problems may seem to 'disappear' in higher light"
So then what physical phenomenon causes noise to increase with intensity?
The S/N ratio increases linearly with intensity because noise is constant, caused by thermal quantum effects. Processing noise is also constant. Each stage in the processing up to the analog to digital conversion adds a bit of noise, which again is constant for all intensities. Noise introduced by digital quantization is also constant for linear AtoD converters. Logarithmic AtoD quantization noise may increase slightly, though still much less than linearly.
I never said S/N isn't relevant. I said "sensitivity and CCD size may not matter". Big difference. Plenty of cheap cameras with horrible optics and cheap CMOS sensors (cheap webcams, pinhole cameras, etc) are highly insensitive under low light but can produce great images under strong lighting conditions. Try it sometime.
The article is a bit misleading, and perhaps wrong. It exchanges one myth for another myth. Indeed megapixels alone do not define resolution. However, CCD size isn't the answer either!
The article fails to address the issue of optical resolution, i.e. lens quality and aperture. Does the number of pixels act as the resolution limiter, or does the quality or size of the lens limit resolution? Many consumer cameras use poor quality small lenses, but boast of large numbers of pixels. Since CCDs are cheap and good lenses aren't, why not over sample the image enough so the consumer thinks they're getting a superior image, and has to pay more for flash memory? The number of pixels can be irrelevant for a camera with a small or cheap lens. Larger aperture lenses will always resolve better, as is the case with all imaging optics anywhere in the spectrum between telescopes and microscopes. Cameras are no different.
The reason professional cameras are better is not just because the CCD is larger. A larger CCD demands a larger lens. That is the difference.
Furthermore, sensitivity and CCD size may not matter at all! The problem of noise for smaller pixels is only relevant when the camera is capturing lower intensity images. Brighter intensities overcome the noise. Larger aperture lenses also collect more light and resolve better, reducing noise and increasing contrast.
You wrote: "Your floor lamp does not put out anything close to 6500k light... Put your lamp bulb in a projector and you will have a projector that will be impossible to calibrate to any sort of decent color balance."
That isn't the issue either.
Flat panel fluorescent backlights and other technologies put out uniform light with great color balance. Furthermore, filters can be used to shape the source and adjust color balance.
The issue is the compactness (light source density) being high enough yet proportionately sized with respect to the projecting and condensing lenses and the LCD/DLP imaging element. A big projector can use a bigger, cheaper light bulb given the same desired screen size.
You wrote: "Your floor lamp does not put out anything close to 6500k light... Put your lamp bulb in a projector and you will have a projector that will be impossible to calibrate to any sort of decent color balance." That isn't the issue either. Flat panel fluorescent backlights and other technologies put out uniform light with great color balance. Furthermore, filters can be used to shape the source and adjust color balance. The issue is the compactness (light source density) being high enough yet proportionately sized with respect to the projecting and condensing lenses and the LCD/DLP imaging element. A big projector can use a bigger, cheaper light bulb given the same desired screen size.
Why must projector bulbs be small, bright and expensive?
In short because the condenser lens (between the light source and LCD/DLP) is not big enough to handle a larger, less expensive light source.
Given size (cost) constraints on the LCD or DLP imaging element and projection and condensing lenses, a proportionately compact and bright source is required. This allows efficient coupling of the light source to the imaging element, achieving full filling of the focal plane (lens aperture) and maximum optical resolution at the projection screen. A larger light source with the same sized imaging element will require a bigger, more expensive condenser lens and mirror, possibly several additional large lenses. A spatial filter can also be used (like a pinhole camera) to boost resolution at the expense of wasted light and heat.
With size, weight and initial cost being the primary concerns, it isn't surprising that projectors ended up with highly consumable light sources.
If you replace the expensive bulbs with a cheaper bulb of the same size the picture will simply be dimmer, and at the same resolution.
You make some good points, but study after study after study have shown that long term investors make significantly more than short-term. It doesn't mean someone CAN'T make a ton of money doing short-term trades, but it IS fair to assume that one time frame is inherently more successful, because it has been proven to be so!
Most of the studies you refer to are based on the US market, not foreign markets. Indeed the US market has had a positive bias over the last 70 years. The average long term participant would have participated in this trend. However, many foreign stock markets (eg Japan) do not show long term upwards bias.
If it were not for a long-term upward bias in the US market, perhaps fewer investors would have bought into the market, further increasing stagnation. It's a self fulfilling prophecy. Furthermore, economic growth must keep pace with stock prices, otherwise valuations get out of control leading to a crash.
One can then argue that the last 70 years has provided unprecedented economic growth that may be hard to match over the next 70 years. Many sources of revenue and efficiency were taped. World economies changed from mostly agrarian to now encompass everything imaginable. Countless technologies were invented. The pace was quickened by WWII, the arms race and space race. Commodities, (and now jobs) move fluidly according to supply and demand. Countless jobs are being replaced by technology.
It's not clear that any of this will lead to economic (revenue) growth to allow stock prices to continue to trend higher. Look at the history of Japan's economy. We seem to be following them more or less. Unless we colonize the moon or mars, the future may more likely be economic stagnation.
According to the posts on elitetrader.com:
h readid=25431
"A guy in my office said it was a trader at Bear. He was supposed to send a market order for 9,000....accidentally sent it for 9,000,000."
Apparently an erroneous sell order (offer) was placed for 9M shares at $42. About 2M shares executed before the remainder of the order was canceled.
Read the real-time reaction of traders here:
http://www.elitetrader.com/vb/showthread.php?s=&t
Everyone realizes the offer is out of line. Some declare "free money!" and purchase as many as they can, then sell at $47, $52, $55, etc. None seem to realize that trades will be busted (canceled) until it's officially announced.
Stocks were never meant to be traded as speculation on the share price.
This is completely false. Investors would never purchase stock without the ability to sell it.
Purchasing stock is purchasing a share of a company's future earnings in the form of dividends.
Future earnings and dividends always have some uncertainty. Traders and investors trade or hold stock positions based on speculation on the future of earnings/dividends.
This is why people who invest long term make more than people who buy expecting to sell with a profit in the same week.
This is completely false. It is possible to be successful with both long term (investing style) and short term (trading style) speculation.
The key to low risk returns is to have a reliable, statistically valid method for speculation. Some find success with a long term fundamentals-based approach, others with exotic neural networks, or other higher frequency analysis. Some can achieve profitability with hundreds of trades per day. It is wrong to assume that any one time frame or bias (eg. long positions only) is inherently more successful.
There are several stocks paying 5-10% real returns as dividends right now.
That's because the stock price has dropped relative to the dividend, while the dividend has remained constant. What most don't realize is that these stock prices AND their dividends are at more risk than 5 to 10%. What good is a 10% annual dividend if the stock drops 25% in the first year?
Try getting that rate at the bank.
Banks offer a very low risk return.
In general:
higher returns == higher risk
lower returns == lower risk