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#51
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Need help in calculating digital camera's MP
On Sat, 03 Jan 2009 19:09:10 GMT, "David J Taylor"
wrote in : John Navas wrote: On Sat, 03 Jan 2009 18:26:14 GMT, "David J Taylor" [] John, I appreciate all of that. I specifically asked about studies comparing RGB to Bayer, and the number of pixels or resultion to make the two equivalent. I obviously have no idea what you want, and can only suggest again that you get thee to Google. You'll find there's no simple answer (like your 2x). This is beginning to sound a bit like the pointless Foveon wars. I don't want to do that again, and I'm personally not terribly interested in resolution the eye can't see, but whatever floats your boat. I agree that there's no simple answer, that's why I thought someone might have done a study. It sounded like a good PhD topic! So riddle me this, David: You're quite prepared to make a pretty aggressive resolution assumption based just on speculation about dissimilar devices (Foveon, 3 CCD), not "studies", but pay no attention to hard data I provide on human perception, demanding precise "studies" instead. Why is that? -- Best regards, John Panasonic DMC-FZ8, DMC-FZ20, and several others |
#52
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Need help in calculating digital camera's MP
John Navas wrote:
[] So riddle me this, David: You're quite prepared to make a pretty aggressive resolution assumption based just on speculation about dissimilar devices (Foveon, 3 CCD), not "studies", but pay no attention to hard data I provide on human perception, demanding precise "studies" instead. Why is that? I didn't ignore the data on human perception, John, but that is well-known to me. Human perception is only half the story. It's what happens when you combine perception with the image production method which matters, and I feel that will be a subjective result rather than something you can calculate, and hence the possible need for further study. I was looking for guidance on what the figure might be, and suggested one possible value - 2 in area, 1.4 linear. I did wonder if anything useful had come from comparisons between Bayer and either Foveon cameras or 3-CCD cameras. David |
#53
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Need help in calculating digital camera's MP
TheRealSteve wrote:
[] Of course it's not as good as a high-quality JPEG. But you won't notice any difference viewing it on most TVs. And of course it's less flexible. But we don't need flexability ... we're authoring a DVD. The advantage it gives you is the ability to use the entire screen of a widescreen TV, without any noticable disadvantages. Steve The OP mentioned nothing about wanting to use a DVD, IIRC. David |
#54
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Need help in calculating digital camera's MP
Paul Furman wrote:
[] Whether 720 or 705... you are saying that's the most a TV can do without burning blu-ray format (is that even possible?). If so I'd say this makes TVs pretty much worthless for viewing still photos. Even a projector will do 1024x768. To get full resolution, you need to avoid using a CD/DVD as the input medium, and either use the VGA connection on the back of the TV, or perhaps (depending on the TV), the SD-slot. Cheers, David |
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Need help in calculating digital camera's MP
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#56
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Need help in calculating digital camera's MP
David J Taylor added these comments in the current discussion du
jour ... HEMI - Powered wrote: [] David, we've had this discussion ad nauseum, namely is "more mega pixels better images" or not. You are obviously correct that few cameras other than toys are less than about 6 MP but that hardly means they are all created equal. Indeed - how annoying might the small amounts of pincushion or barrel distortion in many of today's zoom lenses be when viewed against the dead straight edges on a LCD or Plasma display, if left uncorrected. I suspect that a 1920 x 1080 HD TV display worthy of the name would provide quite a critical environment for viewing images, if for no other reason than its physical size. You should certainly see the benefits of a higher-quality source image. David, I have to say "Huh?!" again here. Yeah, I've seen barrel distortion in a FEW of my pictures depending on lens and focal length but I always fix it BEFORE final save, so if I were displaying on my TV or a HD wide-screen as is the OP, then it would not longer be an issue. -- Jerry, aka HP "If you are out of work and hungry, eat an environmentalist" - Florida billboard |
#57
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Need help in calculating digital camera's MP
David J Taylor added these comments in the current discussion du
jour ... HEMI - Powered wrote: [] Huh?! How does the way a camera "sees" a pixel translate into how a TV sees one? Or, a PC monitor? 16 million color requires 3 bytes per pixel, of course, but how does this matter to a TV? Isn't it far more important how the TV system that reads digital images from, say, it's memory card slot, depend on how well it fills the screen from whatever it is provided? Inded, yes. What I was saying was that in the camera, what we call 2Mpix is not 2Mpix of red, 2Mpix of green, and 2Mpix of blue, so the overall image resolution in RGB pixels is somewhat less than 2Mpix, perhaps 1Mpix for the sake of argument. However, the display does have as many RGB pixels as specified (i.e. 1920 x 1080), and so it can actually display 2Mpix of RGB. So if you want the display to be the limiting factor, send it rather more than 2Mpix of RGB, i.e. something like 4Mpix derived from a Bayer-sensor camera. I can't see how it matters how a camera "sees" a pixel internally. By the time I get to see it on my PC, it IS a normal 3-byte tuple, so a given number of MP is accurate. True enough but my Canon DSLR creates 3:2 images. But, whether a camera is 4:3 or 3:2 or something else, to get all the way to a 16:9/16:10 aspect ratio also requires the photographer to be VERY aware of how they must crop their images or something important will likely be lost. Yes, and having a 16:9 crop frame visible in the finder would be a help. You see this in reverse in TV work, where although the cameras are 16:9, they have the older 4:3 aspect ratio marked (perhaps even with a slight margin), so that the "important" action isn't lost on viewers with older sets.... I agree, but then, it would also be nice on a 3:2 camera if a 4:3 crop frame were also visible, same reason. It is interesting to me, and very disconcerting, that the PC monitor makers seem all of a sudden to have abandoned 4:3 monitors past about 17-19", with seemingly no regard that at this time, FEW people have images of a 16:10 ratio to display without some major cropping and re-editing. -- Jerry, aka HP "If you are out of work and hungry, eat an environmentalist" - Florida billboard |
#58
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Need help in calculating digital camera's MP
HEMI - Powered wrote:
[] David, I have to say "Huh?!" again here. Yeah, I've seen barrel distortion in a FEW of my pictures depending on lens and focal length but I always fix it BEFORE final save, so if I were displaying on my TV or a HD wide-screen as is the OP, then it would not longer be an issue. Yes, of course, anyone who cares about their image quality would indeed to that. BTW: if I recognise it's going to be an issue in an image, I would make fixing it the /first/ step of the processing. The point, though, was that displayed on a large screen, these defects may be more noticeable. Cheers, David |
#59
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Need help in calculating digital camera's MP
David J Taylor added these comments in the current discussion du
jour ... HEMI - Powered wrote: [] David, I have to say "Huh?!" again here. Yeah, I've seen barrel distortion in a FEW of my pictures depending on lens and focal length but I always fix it BEFORE final save, so if I were displaying on my TV or a HD wide-screen as is the OP, then it would not longer be an issue. Yes, of course, anyone who cares about their image quality would indeed to that. BTW: if I recognise it's going to be an issue in an image, I would make fixing it the /first/ step of the processing. The point, though, was that displayed on a large screen, these defects may be more noticeable. I agree with you that fixing either barrel or pincushion distortion should be the first thing done because it allows the FULL mega pixels of the image to be corrected. As I said, I only rarely see any of this at all, but when I do, it is usually on something decidedly rectangular, like a sign or placard I shot to describe the main subject for information purposes. I would also comment that other than correction lens distortion, the next thing I do is to correct any apparent perspective distortion and then crop horizontally for best preliminary composition, resize horizontally to the final size, then crop vertically for best composition. To allow all of those things to work reasonably well, IF I can, I leave maybe 20-25% of "white space around the main subject. Sometimes I cannot do that, for example, when shooting a car at an outside show or in a museum where the widest lens I want to use isn't wide enough and I can't go back further without either running into another car OR in ruining the basic composition by bringing in too much of what is on either side of it. These are all valid points. I only have one HD-capable TV right now, a 27" Sony that also can function as a PC monitor but only at 1024 x 768. I have ran a number of images to this TV via a Panasonic DVR that has an SD card in it. I don't think the Sony's resolution is quite as high as 1920 x 1080, I think it is more like 1780 or thereabouts, but on the occasions I've tried looking at JPEGs, I saw no quality issues due mainly due to the camera. But, to the OP's main question, I imagine they could answer it fully on their own by simply testing some typical digital photographs that are all basically identical except for the mega pixel size and simply observe whether a larger image does or does not truly improve what the eye can see. Have a nice Sunday, David! -- Jerry, aka HP "If you are out of work and hungry, eat an environmentalist" - Florida billboard |
#60
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Need help in calculating digital camera's MP
HEMI - Powered wrote:
[] I can't see how it matters how a camera "sees" a pixel internally. By the time I get to see it on my PC, it IS a normal 3-byte tuple, so a given number of MP is accurate. Yes, at the computer it's a 3-byte RGB triple, but the camera hasn't sensed it that way. At the camera, each pixel will only record one colour, in the so-called Bayer pattern, so that if you consider two rows or two columns of sensors, at the camera it's typically: (R--) (-G-) (-G-) (--B) and the camera's firmware converts these four value to 12 values when presented to the PC: (RGB) (RGB) (RGB) (RGB) The conversion works very well, but it's not perfect, so some resolution is lost during the process. The question I am asking is: how many Bayer pixels are required to provide full quality on an RGB display? [] I agree, but then, it would also be nice on a 3:2 camera if a 4:3 crop frame were also visible, same reason. It is interesting to me, and very disconcerting, that the PC monitor makers seem all of a sudden to have abandoned 4:3 monitors past about 17-19", with seemingly no regard that at this time, FEW people have images of a 16:10 ratio to display without some major cropping and re-editing. Yes, quite it's why I got my 1600 x 1200 monitor - 4:3 aspect ratio - while I still could. Now my images are more likely to be 3:2 aspect ratio from a DSLR, and I expect my next monitor will be 16:10 (1920 x 1200), and I will just accept the black bands.... Cheers, David |
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