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Bayer Megapixels
"Arte Phacting" writes:
A 3.4M sensor with 3 photodetectors per site gives 3.4M times 3 = (erm) 10.2M data values A 6M with 1 photodetector per site gives (I can do this!) 6M times 1 = 6M data values I am trying to figure how a 3.4M sensor can render an image comparable with a 6M or 8M sensor - its just gorra be connected with the quantity of data collected at the sensor. What say y'all? It has been explained repeatedly. Are you not reading? By objective measurements, the 3.4 MP sensor does *not* render an image comparable to a 6 MP or 8 MP sensor - the actual resolution of the 3.4 M sensor is on par with other 3 MP cameras, and clearly inferior to that of 6 MP and higher cameras. The 3.4 MP Sigma cameras only *appear* to have image sharpness comparable to a 6 MP camera because the anti-aliasing filter was omitted from the Sigma camera. This gives images that look like they have more fine detail, but that extra detail is not correctly reproducing information from the original scene. It has nothing to do with making 3 measurements per pixel. Take any 6 MP camera and remove the AA filter, and you'll get extra false detail. Measuring 3 colours at each location instead of 1 *does* improve chroma resolution, but with normal image sizes for screen display or printing the human eye can't see the difference. It also avoids demosaicing mistakes that Bayer images occasionally suffer from. But it doesn't help resolve fine detail at all (unless the fine detail is carefully-constructed colour-only worst-case resolution test charts). Dave |
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Bayer Megapixels
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#3
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Bayer Megapixels
Make way - here comes Artie
But first, the database adage: rubbish in, rubbish out Hokay dokay - how does that affect the topic and this thread in particular? I'll try to explain Suppose pixel count is just a partitioning. A set of horizontal and vertical markers with no mass and no area. In other words a notional addressing system just like those graphs peeps do at school. The addressing system requires data - usually in the from of RGB values - the bigger the number the bigger the photon count. That partitioning system porportions data from photosites I am going to use easy numbers for this example coz I can't be assed with awkward ones) A 3.4M sensor with 3 photodetectors per site gives 3.4M times 3 = (erm) 10.2M data values A 6M with 1 photodetector per site gives (I can do this!) 6M times 1 = 6M data values I am trying to figure how a 3.4M sensor can render an image comparable with a 6M or 8M sensor - its just gorra be connected with the quantity of data collected at the sensor. What say y'all? Artie "Georgette Preddy" wrote in message om... wrote in message . .. In message , (Georgette Preddy) wrote: wrote in message . .. In message , (Georgette Preddy) wrote: http://www.pbase.com/image/23420444 http://www.pbase.com/image/31205398 So according to you, a Red sensor can "spatially witness" Blue or Green optical features. How interesting. Not. That's not what I wrote at all. Yes it is, unfortunately. You think a Bayer sensor can "spatially witness" red features with green sensors, and blue features with red sensors, and green features with blur I mean blue sensors. Obviously that's bunk, do I really need to explain why? You learn more about the image by having more sensors in unique places in the focal plane, even if they each record only one color, because their main job is to perceive luminance at a high resolution, and color is of a secondary resolution priority. A green color filter doesn't pass a blue feature's luminance. That's the whole point. Jeeze. Pity that your mental facilities are too weak to visualize how full-RGB samples are totally unnecessary for photography. Right. |
#4
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Bayer Megapixels
Lets look at this in another way, Just like your computer monitor it takes
three dots to produce a color , could you imagine how much sharper it would be , or how many less color dots on the screen it would take for the same res if each point could produce any color even white. So if a camera can see any color from one point then it would take less pixels compared to a multi filtered system for a given sharpness. Simple logic. "Brian C. Baird" wrote in message .. . In article , says... A 3.4M sensor with 3 photodetectors per site gives 3.4M times 3 = (erm) 10.2M data values No. The 10.2M values are interpolated to form 3.4M usable values. A 6M with 1 photodetector per site gives (I can do this!) 6M times 1 = 6M data values Not quite. Due to the mosaic process, you lose a few pixels to give you a clean edge. That's why you read about "effective megapixels" being slightly smaller than the total number of photodetectors. I am trying to figure how a 3.4M sensor can render an image comparable with a 6M or 8M sensor - its just gorra be connected with the quantity of data collected at the sensor. Quick answer: it can't. What say y'all? Artie Go read a book, Artie. |
#5
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Bayer Megapixels
"Arte Phacting" wrote: I beg to differ Dave :-) Then you are wrong. rendering an image is based on data - the data picked up by a sensor Only when that data is from unique points in space. Consider a 3.4 MP camera that divides the spectrum into 9 narrow bands by taking 9 readings at each point. Would such a camera have three times the resolution of the SD9? Of course not. It would have completely meaningless spectral reproduction that no human could see as being in any way different. It would be able to do a few cutesy tricks, like emulating B&W film response curves better. The more data, the greater integrity and fidelity of the data the more output devices and DSP have to work on. Data costs. At the pixel, you have to store three charges instead of one. That means higher noise/lower dynamic range. You need three times as many A/D conversions. More battery drain. You need 3 times as much storage for RAW images. For the same amount of data, Bayer cameras provide three times the image quality. The Foveon concept is incredibly bad engineering. David J. Littleboy Tokyo, Japan |
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Bayer Megapixels
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#7
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Bayer Megapixels
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#8
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Bayer Megapixels
I beg to differ Dave :-)
rendering an image is based on data - the data picked up by a sensor The more data, the greater integrity and fidelity of the data the more output devices and DSP have to work on. Imagine a 2 sensel sensor. Only so much can be done with the data whether it is a stacked or one layer sensor. Quantity and quality count. The more of a beasting the data experience the more it's gonna shift in terms of integrity and fidelity to the original image Artie "Dave Martindale" wrote in message ... "Arte Phacting" writes: A 3.4M sensor with 3 photodetectors per site gives 3.4M times 3 = (erm) 10.2M data values A 6M with 1 photodetector per site gives (I can do this!) 6M times 1 = 6M data values I am trying to figure how a 3.4M sensor can render an image comparable with a 6M or 8M sensor - its just gorra be connected with the quantity of data collected at the sensor. What say y'all? It has been explained repeatedly. Are you not reading? By objective measurements, the 3.4 MP sensor does *not* render an image comparable to a 6 MP or 8 MP sensor - the actual resolution of the 3.4 M sensor is on par with other 3 MP cameras, and clearly inferior to that of 6 MP and higher cameras. The 3.4 MP Sigma cameras only *appear* to have image sharpness comparable to a 6 MP camera because the anti-aliasing filter was omitted from the Sigma camera. This gives images that look like they have more fine detail, but that extra detail is not correctly reproducing information from the original scene. It has nothing to do with making 3 measurements per pixel. Take any 6 MP camera and remove the AA filter, and you'll get extra false detail. Measuring 3 colours at each location instead of 1 *does* improve chroma resolution, but with normal image sizes for screen display or printing the human eye can't see the difference. It also avoids demosaicing mistakes that Bayer images occasionally suffer from. But it doesn't help resolve fine detail at all (unless the fine detail is carefully-constructed colour-only worst-case resolution test charts). Dave |
#9
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Bayer Megapixels
cheers Brian - I love u 2 blush
Nah then, I think the diary read for this week will be: rubbish in, rubbish out I think different issues are being melded together without clarity of vision. I am trying to give the view that a sensor has a job to do - it is a data accumulater-sensing device That's all, no more & no less Image processing and image rendering are separate parts of the process. To make up for the shorfall in data some fantastic DSP happens - and very good it is too But all it does is just dress the data prior to processing on or in output devices Don't you agree? This is getting way back to the original point in a thread somewhere that a sensor outputs an image. It doesn't - a sensor needs a heck of a lot of supporting kit before an image may be observed. Artie "Brian C. Baird" wrote in message .. . In article , says... A 3.4M sensor with 3 photodetectors per site gives 3.4M times 3 = (erm) 10.2M data values No. The 10.2M values are interpolated to form 3.4M usable values. A 6M with 1 photodetector per site gives (I can do this!) 6M times 1 = 6M data values Not quite. Due to the mosaic process, you lose a few pixels to give you a clean edge. That's why you read about "effective megapixels" being slightly smaller than the total number of photodetectors. I am trying to figure how a 3.4M sensor can render an image comparable with a 6M or 8M sensor - its just gorra be connected with the quantity of data collected at the sensor. Quick answer: it can't. What say y'all? Artie Go read a book, Artie. |
#10
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Bayer Megapixels
cheers Brian - I love u 2 blush
Nah then, I think the diary read for this week will be: rubbish in, rubbish out I think different issues are being melded together without clarity of vision. I am trying to give the view that a sensor has a job to do - it is a data accumulater-sensing device That's all, no more & no less Image processing and image rendering are separate parts of the process. To make up for the shorfall in data some fantastic DSP happens - and very good it is too But all it does is just dress the data prior to processing on or in output devices Don't you agree? This is getting way back to the original point in a thread somewhere that a sensor outputs an image. It doesn't - a sensor needs a heck of a lot of supporting kit before an image may be observed. Artie "Brian C. Baird" wrote in message .. . In article , says... A 3.4M sensor with 3 photodetectors per site gives 3.4M times 3 = (erm) 10.2M data values No. The 10.2M values are interpolated to form 3.4M usable values. A 6M with 1 photodetector per site gives (I can do this!) 6M times 1 = 6M data values Not quite. Due to the mosaic process, you lose a few pixels to give you a clean edge. That's why you read about "effective megapixels" being slightly smaller than the total number of photodetectors. I am trying to figure how a 3.4M sensor can render an image comparable with a 6M or 8M sensor - its just gorra be connected with the quantity of data collected at the sensor. Quick answer: it can't. What say y'all? Artie Go read a book, Artie. |
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