Luminous Landscape Forum
Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: WarrenMars on January 25, 2010, 06:21:52 pm
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No doubt many readers know this already but I was truly SHOCKED to discover that each supposed pixel in my camera contains only the data for one colour! This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
I have been aware of interpolation and the demosaicing step for years, but I had always assumed that this was to make small realignments to centre the 4 elements of the Bayer mosaic within the pixel. It never occurred to me that it was being used to invent colour data for three quarters of the image!!! It was only when I was stepping through the main data structure at runtime in Dave Coffin's DCRAW (http://www.cybercom.net/~dcoffin/dcraw/dcraw.c)code and wondering why only one quarter of it was filled in that the penny finally dropped. Shocked I tell you!
Ken Rockwell is right (http://www.kenrockwell.com/tech/bayer.htm). The manufacturers are LYING! Interpolated pixels are not real pixels. Made up data is not real data. We have all been conned. Sure, the interpolation used these days is very good! In areas without sudden transitions the invented detail is accurate, but in areas of fine detail: Ouch! It isn't!
There are laws about misrepresenting the specs of one's products. A minor inflation of one's resolution might be acceptable, but 400%? Surely that's illegal, not to mention immoral.
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Interesting. I can't wait to see where this thread goes. I would really like more information.
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Actually, it's ~.66 per dimension since it's in a triangular arrangement. With good interpolation software, it might edge up to about .7x in each dimension, but that's the limit of a Bayer pattern. It's a quick and mostly effective kludge to turn analog into digital results, much like how you see screens used in offset printing(just take a magnifying glass to any printed magazine)
Your 10MP DSLR is something like 3800X2600 pixels, give or take? So that's really about 3800X 0.7 X 2800X 0.7. Roughly 2650X1950(5.2 actual full-color locations). 35mm film is typically scanned in a DLab to roughly 6.7MP - or roughly 12-14MP depending on which Digital camera you're comparing it to.
It's a known problem, but it's not nearly as bad as you make it out to be.
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This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
Since, those 2.5 MP grids are phase-offset, that means that each of them have some unique information and they may be processed together, synergetically, to produce an output that is quite higher than the individual 2.5 MP. It is not unsurprising that one may be able to get 6-8 MP back, which is of course, much higher than 2.5 MP.
BTW, in a different, but somewhat related domain, fewer numbers than expected does not necessarily mean loss in reconstruction. Think about this: If you know a sine wave's frequency, amplitude, and phase, just 3 numbers, you can obtain infinite values of that wave. So an otherwise infinite storage requires only 3 numbers to reconstruct that.
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To view, or not to view- that is the question:
Whether 'tis safer for the mind to suffer
The mounting horror of outrageous posting,
Or to takes arms against a sea of opinions,
And, by touching the “shut down” switch, end them.
No, I'll bite. Warren, life is mostly lies, beginning with your eyesight. Rather poor information is taken from the eye and constructed into reality in your head, and the brain Photoshops out the dodgy bits. It's life. Get over it.
On the other hand, while I'm not too worried about accurate colour and rather want predictable colour, I too can't wait to see where this goes.
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No doubt many readers know this already but I was truly SHOCKED to discover that each supposed pixel in my camera contains only the data for one colour!
This (the approx. fact, not the discovery) is not exactly true, and half (or quarter ) truths are dangerous.
Each sensel holds the result of an approximate 1/3rd of the relevant visual spectrum, but (usually) after an Optical Low Pass Filter (OLPF, AKA AA-filter) has done its work. For chromatic information that's not too much of a chore to reconstruct, reconstucting luminance information, that will require a bit more cleverness.
This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
Wrong. I suggest trying to measuring the actual resolution after a good CFA demosaicing. Sure R/G/B resolution individually will not achieve its theoretical maximum for the pixel density, but it will meet (or even exceed!) the sampling density.
I have been aware of interpolation and the demosaicing step for years, but I had always assumed that this was to make small realignments to centre the 4 elements of the Bayer mosaic within the pixel.
That would be a very poor way to demosaic images. The Bayer CFA is much more clever in design, and implementation.
It never occurred to me that it was being used to invent colour data for three quarters of the image!!!
Wrong again, it doesn't "invent" color data, it estimates the missing data from clues in its immediate surroundings (and it does so in a very convincing manner, especially for chrominance).
It was only when I was stepping through the main data structure at runtime in Dave Coffin's DCRAW (http://www.cybercom.net/~dcoffin/dcraw/dcraw.c)code and wondering why only one quarter of it was filled in that the penny finally dropped. Shocked I tell you!
Too bad it required studying Dave's code. It's mostly common knowledge, at least around these quarters ...
Cheers,
Bart
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This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
What?
Seriously. Did your pictures lose 3/4 of their appeal after you found this out?
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No doubt many readers know this already but I was truly SHOCKED to discover that each supposed pixel in my camera contains only the data for one colour! This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
I have been aware of interpolation and the demosaicing step for years, but I had always assumed that this was to make small realignments to centre the 4 elements of the Bayer mosaic within the pixel. It never occurred to me that it was being used to invent colour data for three quarters of the image!!! It was only when I was stepping through the main data structure at runtime in Dave Coffin's DCRAW (http://www.cybercom.net/~dcoffin/dcraw/dcraw.c)code and wondering why only one quarter of it was filled in that the penny finally dropped. Shocked I tell you!
Ken Rockwell is right (http://www.kenrockwell.com/tech/bayer.htm). The manufacturers are LYING! Interpolated pixels are not real pixels. Made up data is not real data. We have all been conned. Sure, the interpolation used these days is very good! In areas without sudden transitions the invented detail is accurate, but in areas of fine detail: Ouch! It isn't!
There are laws about misrepresenting the specs of one's products. A minor inflation of one's resolution might be acceptable, but 400%? Surely that's illegal, not to mention immoral.
Have you tried counting the pixels in an image to really see how many there are? I think it's more likely that manufacturer's are telling the truth as they see it and Ken Rockwell doesn't have a clue
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Ken Rockwell is right (http://www.kenrockwell.com/tech/bayer.htm). The manufacturers are LYING! Interpolated pixels are not real pixels. Made up data is not real data. We have all been conned. Sure, the interpolation used these days is very good! In areas without sudden transitions the invented detail is accurate, but in areas of fine detail: Ouch! It isn't!
Wow bud...guess you don't know too much about old Ken do ya...if you did, you wouldn't be pointing him out as a raw of truth (unless you were actually being sarcastic).
Really, you just discovered what a Bayer array is? Boy, you live a sheltered life...and ya know, you really SHOULD NOT believe everything you read on the internet...of wait, I think you just figured that out recently huh?
:~)
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Ken Rockwell is right (http://www.kenrockwell.com/tech/bayer.htm).
Now there's your problem ... he'll say absolutely anything to get hits (that's how he makes his money) , and I'm not sure he has a clue about the actual technology itself.
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Actually one can estimate the lower bound for the perceived resolution by taking the number of green pixels, which in a Bayer pattern accounts for 50 percent of the total number of pixels. To the human eye green represents the major part of luminance and therefore sharpness information. In combination with interpolation from the red and blue pixels the achieved "real" resolution lies roughly between 60 and 70 percent of the total pixel count.
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Actually one can estimate the lower bound for the perceived resolution by taking the number of green pixels, which in a Bayer pattern accounts for 50 percent of the total number of pixels. To the human eye green represents the major part of luminance and therefore sharpness information. In combination with interpolation from the red and blue pixels the achieved "real" resolution lies roughly between 60 and 70 percent of the total pixel count.
That depends on the subject, and on the demosaicing technology used, but it is usually better than people think, or want us to believe. I've tried to determine the real loss of resolution, and it can be as little as 6.4% for luminance only. Here (http://www.xs4all.nl/~bvdwolf/main/foto/bayer/bayer_cfa.htm) is a simple experiment I documented 6 years ago. This was before I got hold of real (deconvolution) sharpening routines instead of simple edge contrast enhancements like USM.
Cheers,
Bart
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What?
Seriously. Did your pictures lose 3/4 of their appeal after you found this out?
All prints 75% off =) Dontcha love a post that has nothing to say? (I'm referring to myself here)
On the other hand, just take it for face value. Your prints haven't gotten any smaller and your photos will still look exactly the same.
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No doubt many readers know this already but I was truly SHOCKED to discover that each supposed pixel in my camera contains only the data for one colour! This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
Ken Rockwell is right (http://www.kenrockwell.com/tech/bayer.htm). The manufacturers are LYING! Interpolated pixels are not real pixels. Made up data is not real data. We have all been conned. Sure, the interpolation used these days is very good! In areas without sudden transitions the invented detail is accurate, but in areas of fine detail: Ouch! It isn't!
Technically, the manufacturers are right. The pixels are there, and there's just a filter array in front of them. Many CCDs are available in both versions, with and without a CFA. If the issue is really of interest to you, rather take a top-down approach I would suggest a bottom-up approach. The astronomy CCD books give a solid foundation, but it isn't mandatory to buy them. There are good resources on the web. The "fishing for photon" serie by Craig Stark is a great start http://www.cloudynights.com/category.php?category_id=181 (http://www.cloudynights.com/category.php?category_id=181)
Another great resource can be found here
http://www.olympusmicro.com/primer/java/index.html (http://www.olympusmicro.com/primer/java/index.html)
with very nice animated tutorials.
When you are familiar with that aspect of things, you move up to "fancier" sensors such as CMOS, add CFAs, look into the methods used to minimize read noise, etc...
One thing to keep in mind is that since the digital imaging field is so hot scientifically, commercially and has a lot of military applications, tens of thousands of great minds are at work in their own subfields. Unfortunately Ken Rockwell isn't in that category. He is a fairly decent entertainer who makes strong statements aimed at an unsophisticated audience. In some cases, he is just plain wrong. In other cases, he states the obvious and makes a mountain out of it. In a way, he's the web equivalent of the UK tabloid, fishing for audience at any cost. Keep in mind that tabloids can be right at times, as some pro golfer learned.
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I think this might be the antidote to his state of agitation?
http://www.foveon.com/article.php?a=67 (http://www.foveon.com/article.php?a=67)
Funnily enough I haven't read anything about an image taken with this sensor being superior to one of the "normal" ones?
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One thing to keep in mind is that since the digital imaging field is so hot scientifically, commercially and has a lot of military applications, tens of thousands of great minds are at work in their own subfields. Unfortunately Ken Rockwell isn't in that category. He is a fairly decent entertainer who makes strong statements aimed at an unsophisticated audience. In some cases, he is just plain wrong. In other cases, he states the obvious and makes a mountain out of it. In a way, he's the web equivalent of the UK tabloid, fishing for audience at any cost. Keep in mind that tabloids can be right at times, as some pro golfer learned.
No, he's the photography equivalent of Rush Limbaugh, without the hostility.
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Bayer pattern is the industry standard for color photography, counting the individual pixels aren’t cheat. They are using this since the beginning. Some comparison of individual bayer pixels can’t be aligned with resolution in lpmm. There is some dark ages misinformation on comparing film and digital. On digital realm that’s the standard. Non bayer sensors, foveons or B&W are the exceptions.
Best,
Alex
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I think this might be the antidote to his state of agitation?
Ouch! Second time warp in less than 20 posts! That DOES hurt!
Better turn it on the side to get a transmogrifier than playing with the time machine... Oh! No! A duplicator! This thread is duplicated now!
(with due respect (http://en.wikipedia.org/wiki/Calvin_and_Hobbes#cardboard_boxes))
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I think this might be the antidote to his state of agitation?
http://www.foveon.com/article.php?a=67 (http://www.foveon.com/article.php?a=67)
Funnily enough I haven't read anything about an image taken with this sensor being superior to one of the "normal" ones?
Well, pretty amazing that Foveon. So what's the scoop on this image sensor? Good, bad, better?
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No doubt many readers know this already but I was truly SHOCKED to discover that each supposed pixel in my camera contains only the data for one colour!
[!--quoteo(post=0:date=:name=WarrenMars)--][div class=\'quotetop\']QUOTE (WarrenMars)[div class=\'quotemain\'][!--quotec--]I am one of the few photographers who really understand the nitty gritty of how these cameras work[/quote]
Which is it, Warren?
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Which is it, Warren?
Just aliasing. You aren't sampling his messages at the correct frequency. You could try interpolating an interpretation, unless you have reasons to believe one of the statements is an artifact. ;-)
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That depends on the subject, and on the demosaicing technology used, but it is usually better than people think, or want us to believe. I've tried to determine the real loss of resolution, and it can be as little as 6.4% for luminance only. Here (http://www.xs4all.nl/~bvdwolf/main/foto/bayer/bayer_cfa.htm) is a simple experiment I documented 6 years ago. This was before I got hold of real (deconvolution) sharpening routines instead of simple edge contrast enhancements like USM.
Cheers,
Bart
Nice demonstration. What algorithm did you use for the demosaic?
BTW, Bart, is there an index page on your site that links to all your articles? I can't find it by backing out of the above URL (or the one on aliasing).
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Just aliasing. You aren't sampling his messages at the correct frequency. You could try interpolating an interpretation, unless you have reasons to believe one of the statements is an artifact. ;-)
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Nice demonstration. What algorithm did you use for the demosaic?
Hi Emil,
I used DMMD's "Pictura" (http://www.dmmd.net/research/demosaicing.html) beta software, but it's no longer available at their site (i.e. I cannot find it there anymore). It used a so-called "Adaptively Quadratic (AQua (http://www.dmmd.net/research/publications/journal/aqua.pdf)) Image Interpolation" method which produced good demosaicing results.
BTW, Bart, is there an index page on your site that links to all your articles? I can't find it by backing out of the above URL (or the one on aliasing).
No, there is no index, and backing out is blocked. I wrote most of those short articles to avoid having to answer the same questions over and over again in Usenet discussions (they are still useful for that purpose today it seems).
There are additionally only some articles (http://www.xs4all.nl/~bvdwolf/main/foto/scan/se5400/se5400.htm) about scanning (mainly oriented at the Minolta SE 5400), but I never finished the entire analysis because the model was succeeded by a newer one, and Minolta was abandoning that market segment, so I didn't feel motivated to 'recommend' that scanner anymore. Service was also becoming problematic, and 35mm film scanning was being replaced by 16+ MPixel cameras with better enlargement potential. I still use the scanner for my old films, and Vuescan as it's driver because there is no support for modern operating systems from the manufacturer.
Cheers,
Bart
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If it bothers you so much get a Sigma. Although it lies even more about its non-Bayer sensor. It claims three times the resolution which it doesn't even get close to. All cameras have to work with GRBG except for the Sigma which is RBG. Since it is universal it should just be considered a given and take into account that the results are so good. They would be more accurate if they gave the interpolated values but that's modern marketing. You can make a print several feet in length with todays sensors so they are doing something right. If you are really adventurous you could have your anti-AA filter removed which would allow you to get the most from the pixels that are there, as long as nothing causes moire.
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We have all been conned.
Trolled is more like it.
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We could turn it into a productive effort though. Is Foveon better than Bayer?
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Seriously. Did your pictures lose 3/4 of their appeal after you found this out?
Amazingly Yes! I was so disappointed that I had to get rid of 3/4 of them.
More seriously, I'm surprised so many of you think interpolation gives you back 3 times the information you actually have! You need 3 colours to make a real pixel, there's just no way around that fact. The extra green is simply a waste of time put there to make the grid a square. Thus it is that in a Bayer array you need 4 pixels to make 1. Your true resolution IS 1/4 the advertised.
You can delude yourself that sophisticated algorithms put back what wasn't there in the first place, but anyone who has studied noise theory should know that is not possible. All you can do is GUESS, which is what interpolation does. Sure, your guesses might be correct a good percentage of the time, but that's not the same thing as having the ACTUAL data. You wanna shoot motor cars and chick's faces? Interpolation is for you! You wanna shoot foliage and landscapes? Better get some more pixels!
Foveon's multi-chromatic sensor sounds good in theory, but a look at Sigma's output will quickly convince you that it doesn't produce in reality. If the answer is in that direction they're a long way from it. I'll tell you something that WILL improve the situation: A three colour filter!
The conventional filter is 4 squares to make a square, wasting 1/4 of the area. But we don't HAVE to have square sub-pixels! Let's use 3 rectangles of width 1/3 the height. 3 rectangles to make a square! This will improve the resolution by 1/3. Not huge, I'll admit, but a useful improvement!
Go to it Manufacturers!
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Or, just consider the camera you already have to posess 1/4 its stated pixel count. Voila! Fully sampled 'macropixels' with 2x oversampling in green!
(And way better S/N performance than the 'skinny sensel' solution).
QED.
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is simply a waste of time put there to make the grid a square. Thus it is that in a Bayer array you need 4 pixels to make 1. Your true resolution IS 1/4 the advertised.
If you were capturing an image at a single (or a small range of) wavelength(s) matching the transmission curves of the respective filters in the array, roughly yes, you'd have 1/2 in G, 1/4 in R and 1/4 in B. However, that usually isn't the type of images photographers captures.
And believe it or not, researchers have been looking for better sensors for a while
http://johncompton.pluggedin.kodak.com/def...asp?item=624876 (http://johncompton.pluggedin.kodak.com/default.asp?item=624876)
Incidentally, note that their main purpose isn't what you think it should be.
You'll be, I am sure, "SHOCKED" to discover that not only did the CFA steal your pixels, it also refused entry to your photons!
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More seriously, I'm surprised so many of you think interpolation gives you back 3 times the information you actually have! You need 3 colours to make a real pixel, there's just no way around that fact. The extra green is simply a waste of time put there to make the grid a square. Thus it is that in a Bayer array you need 4 pixels to make 1. Your true resolution IS 1/4 the advertised.
Welcome to 2003, Warren. While Bayer matrix does not sample every color at every pixel location, but it does sample something at every pixel location. So with a properly-designed AA filter to ensure there is some degree of correlation between every pixel and its immediate neighbors, one can accurately "guess" (interpolate) average luminance for every pixel in the image, at the expense of color accuracy in fine details. Green appears twice in the matrix because human vision is more sensitive to green than red or blue, and color errors in the green channel are more visible than the red or blue channels. It's not "simply a waste of time put there to make the grid a square", it's a carefully considered engineering compromise that allocates the most real data to the wavelength range that needs it most, based on the perceptual response of human vision.
The net result is much better than you claim; if you compare Bayer images to Foveon images (which do sample all three color channels at each pixel location) you will find that Foveon images are better pixel-for-pixel than Bayer images. After the proper sharpening for each image (deconvolution-based, NOT simple USM), the Foveon is only about 1/3 better; a 4MP Foveon image need between 5 and 6 Bayer MP to match overall resolution and detail. If you were correct, the Bayer camera would need 16MP to match a 4MP Foveon image, and if you actually compare images, this is far from the case.
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...
Pass whatever you are smoking down this way ...
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Pass whatever you are smoking down this way ...
I dunno man, I think he got some bad stuff. Paranoia and all...
In all seriousness, we can argue about the math, the physics and the technology all day long. Ultimately though, it doesn't matter if my camera is really the 10mp it claims or not. That's just nomenclature. What matters is how the 12x18 hanging on my wall right now looks. As a matter of fact, it looks great. It's kinda like saying that a car isn't really a V6 because all six cylinders don't fire at the same time. It's an arbitrary distinction. It's the real-world performance that matters.
Besides, even if we somehow forced manufacturers to state the "correct" number of megapickles, it wouldn't do anything but confuse people. Even if the numbers aren't technically correct, everyone knows what kind of resolution they can expect from a 10mp camera, or a 24mp camera.
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Wow: I'm amazed nobody started complaining about this blurring filter these villain manufacturers put in front of the sensor to drop the achievable resolution even lower
On the other hand the jpg's and tif's I get from my camera meet the pixel count they claim so I really don't get what's the problem
OK, let's get serious. I like this thread as some of the technical explanations about the subject increased my understanding of what's really happening. Thanks for those
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It was a one-eyed, one-horned, flying purple pixel eater...
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that test he did seems to me absolutely pointless...
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No doubt many readers know this already but I was truly SHOCKED to discover that each supposed pixel in my camera contains only the data for one colour! This means that the true resolution of my camera is only a QUARTER of its advertised value! My 10MP SLR is really only 2.5MP!
I have been aware of interpolation and the demosaicing step for years, but I had always assumed that this was to make small realignments to centre the 4 elements of the Bayer mosaic within the pixel. It never occurred to me that it was being used to invent colour data for three quarters of the image!!! It was only when I was stepping through the main data structure at runtime in Dave Coffin's DCRAW (http://www.cybercom.net/~dcoffin/dcraw/dcraw.c)code and wondering why only one quarter of it was filled in that the penny finally dropped. Shocked I tell you!
Ken Rockwell is right (http://www.kenrockwell.com/tech/bayer.htm). The manufacturers are LYING! Interpolated pixels are not real pixels. Made up data is not real data. We have all been conned. Sure, the interpolation used these days is very good! In areas without sudden transitions the invented detail is accurate, but in areas of fine detail: Ouch! It isn't!
There are laws about misrepresenting the specs of one's products. A minor inflation of one's resolution might be acceptable, but 400%? Surely that's illegal, not to mention immoral.
Maybe you should alert the UN, or Homeland Security, or the FBI. This is REALLY IMPORTANT!
Sensors don't have pixels, images have pixels.
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Maybe you should alert the UN, or Homeland Security, or the FBI. This is REALLY IMPORTANT!
Sensors don't have pixels, images have pixels.
Maybe he was pixelated when he wrote it
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You guys got me worried about Pixel Theft, so I dropped everything and started counting the pixels on my Canon 5D's sensor. Unfortuantely, I fell asleep less than halfway through the second row, so I don't know whether any of mine are missing.
I guess I'll have to get a Pixel-Peeping Watch Dog to guard any remaining pixels.
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It was a one-eyed, one-horned, flying purple pixel eater... wacko.gif
Mos def the funniest line so far!
And believe it or not, researchers have been looking for better sensors for a while
http://johncompton.pluggedin.kodak.com/def...asp?item=624876 (http://johncompton.pluggedin.kodak.com/def...asp?item=624876)
Interesting to look at Kodak researchers work. No question as to why Kodak are going out the back door. So they're gonna do the old "get the missing colour by subtracting the other 2 from the total" trick, as used in DVDs. Not a bad scheme I guess, but why include the 3rd colour at all if you're gonna go that???
Anyway, it's an extra level of complexity that we don't need, although it will give the same resolution improvement as my previous suggestion.
It may be that rectangular pixels are tricky to make micro lenses for, (perhaps someone else might have a handle on this?), so how about this for a better array?
(http://warrenmars.com/pictures/misc/triangular_filter_array.gif)
Each triangle is an image pixel. You get 2x the image pixels that you have in reality. This is cheating folks, but it's NOT interpolation! What's more, it's dead easy! Just use the values of the 3 corner pixels. SIMPLE AND ACCURATE!
Ok, folks, tell me it's been done already...
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Warren,
Are you being deliberately provocative are do you really not understand this stuff?
Michael
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Ok, folks, tell me it's been done already...
This has been done with monitors. Hitachi's Diamondtron technology used a similar arrangement.
Fuji's sensor is similar as well - it has diagonally arranged pixels. It helps a little.
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Warren,
Are you being deliberately provocative are do you really not understand this stuff?
Michael
Perhaps, oh Super Administrator, you could dazzle us all with your infinite wisdom and infallible knowledge by contributing to this discussion...
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Perhaps, oh Super Administrator, you could dazzle us all with your infinite wisdom and infallible knowledge by contributing to this discussion...
You are kidding right?
Why the F#%$^CK should Michael bother to follow a thread as stupid as what you have posted here bud?
Seriously, your are a twisted-sister dooode..
I've looked at a variety of web sites you've set up_you don't fall into the category of "somebody who has half a clue".
Michael has a lot more interesting things to spend his time dealing with...
Sorry, I don't meant to speak for Mike (actually, since I'm pretty darn sure he thinks you are a major crackpot-I think I'm not far off) but in the grand scheme of things, what YOU think about ANYTHING seems to fall WAY into the category of "who the F&CK cares".
Seriously, you shouldn't be wasting the bandwidth...some people actually have a day job.
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I believe this thread should be closed.
It's becoming increasingly unpleasant and annoys me each time when
it pops up in the "new posts since your last visit" page ...
And with this I'm off from the thread and won't post on it anymore ....
Sincerely
~Chris
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Amazingly Yes! I was so disappointed that I had to get rid of 3/4 of them.
More seriously, I'm surprised so many of you think interpolation gives you back 3 times the information you actually have! You need 3 colours to make a real pixel, there's just no way around that fact. The extra green is simply a waste of time put there to make the grid a square. Thus it is that in a Bayer array you need 4 pixels to make 1. Your true resolution IS 1/4 the advertised.
You can delude yourself that sophisticated algorithms put back what wasn't there in the first place, but anyone who has studied noise theory should know that is not possible. All you can do is GUESS, which is what interpolation does. Sure, your guesses might be correct a good percentage of the time, but that's not the same thing as having the ACTUAL data. You wanna shoot motor cars and chick's faces? Interpolation is for you! You wanna shoot foliage and landscapes? Better get some more pixels!
Sigh. Warren... just a gentle hint. Please don't claim shock-horror insider knowledge when you are missing the basic, well-understood and UTTERLY public facts about how a digital camera sensor works. Frankly, you're totally clueless right now. Expressing surprise at how a Bayer pattern works, then lecturing us on what the deconvolution algorithms can and can't recover seems a bit... well.. silly.
Not to mention insulting. Has it occured to you that some people on here might understand in considerable depth and detail how all this stuff works- not least, Michael?
Bayer patterns have been around since 1975 and have become the dominant means of imaging RGB with CCD and CMOS for the very good reason that they work extremely well, providing a good sampling of luminance and a lower subsampling of colour, matching human perception fairly well. They are also relatively easy to manufacture and hence cheap to produce, which is why we all have cameras in our mobile phones.
This is well understood- so well understood that it is described in background to the recent Nobel Prize for physics jointly awarded to the inventors of the CCD last year: http://nobelprize.org/nobel_prizes/physics...09/phyadv09.pdf (http://nobelprize.org/nobel_prizes/physics/laureates/2009/phyadv09.pdf)
Get out a nice textbook or two on the subject, please? Go away, and don't come back until you have read and understood them, and the 45+ year old physics on which they are based (and the 100+ year old statistics behind them, too). Your posts are just trolling right now.
Hywel
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I think this sums up the situation?
http://en.wikipedia.org/wiki/Troll_%28Internet%29 (http://en.wikipedia.org/wiki/Troll_%28Internet%29)
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Actually, I hadn't felt the thread become 'unpleasant' until the Resident Rottweiler bit again.
I, for one, am far from expert on these matters and am rapidly coming to the conclusion that many other people are keeping me company without being aware of it. Indeed, I am starting to believe that there is probably much lack of definitive information or understanding of this topic that extends right up to camera manufacturers. How else to account for some of the problems that new cameras exhibit?
I think that part of the problem is that we are stepping into a world where some willingly accept being misled, in the sense of false claims - an acceptance of ad-speak, shall we say - which is what I see underlying the posted replies of 'it gives great prints, so it doesn't matter' which, to me, is nothing more than the same thing reflected in the willing acceptance of poor quality control or false claims for zoom lens performance. I'm sorry, but I think that companies should indeed be held to the letter of their published claims; why should we be slipping into this easy belief that it isn't important if exaggerated claims are made for a product? It darn well does matter; slippery slopes are just that. Look around us all at the world of newspapers, television and politics, never mind marketing, and you would be blind to miss the fact that we are being conned every minute of the day; this is acceptable? Laissez-faire is a dangerous attitude.
Rob C
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Profit motive is the reason for this. If I want to buy a product such as a camera or a lens then I will go to the manufacturer's site and look at the specifications. I will then look through some forums such as this and try and sort the wheat from the chaff. I will look at a couple of magazines. If I am buying then I will cross my fingers and hope what I have read is worthwhile? Remember very few photographer's - or other consumers - will admit to buying a poor product? The worst comment is .... I have one and I am luvving it? There are of course trolls in forums, the misinformed who won't change their mind if you hit them over the head with a hammer and those, as you mentioned Rob, who have never learned manners and continue to use ill informed posting techniques? Sometimes all of us are wrong and rarely admit it? An abundance of common sense goes a long way?
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Indeed, I am starting to believe that there is probably much lack of definitive information or understanding of this topic that extends right up to camera manufacturers. How else to account for some of the problems that new cameras exhibit?
You mean, it's a color moiré pattern issued from Bayer pattern demosaicing that did misguide the alien pilots and lead to Roswell's crash, and it's that truth that has been covered up ever since by the people of Xenu?
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This thread is now closed.
Mr. Mars – please do some basic reading on a topic before posting here again. This isn't DPreview.
(I took my nice pill this morning, otherwise I'd be more sarcastic.)
Michael