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#31
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Faking and expensive tilt-shift lens
On Mon, 09 Feb 2009 11:19:49 -0800, nospam
wrote: In article , John A. wrote: On a Bayer-filtered sensor 1/2 pixel = 1 photosite. that's incorrect. You're right. That should have been 1/4 pixel instead of 1/2. I was thinking one-dimensionally. See my other post, though, for further clarification and correction of my thinking. |
#32
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Faking and expensive tilt-shift lens
On Mon, 09 Feb 2009 21:34:29 GMT, John A. wrote:
And a pixel IS made of 2x2 photosensors on a Bayer-filtered sensor array. The sensors are arranged something like this: G R B G Together, those four photosensors make up one pixel. Ahhh... But I think I see what you're talking about. That's in a single-exposure Bayer system. In the theoretical four-exposure system we are discussing we would get four three-color synthesized pixels from each 2x2 Bayer array. (Minus a row and a column for the image, I believe, assuming we'd only keep the overlapping portions of the four exposures.) That was what you meant, right? So maybe we both get it, and don't get it. =D Gotcha! But no, the G R B G photo sensors don't make up one pixel. If they did, then a 12mp sensor would have 48 million little silicon RGBG thingies. Some advanced amateurs have been known to physically remove the bayer filter, using powerful solvents to dissolve it. A de-Bayered 12mp sensor then becomes a monochrome 12mp sensor, not a 48mp sensor. In a way, the Bayer filter cheats a bit. The intensity of each colored pixel is calculated by interpolating (demosaicing) the value of the light that it registers as well as that of the differently colored pixels that surround it. The result isn't 100% accurate, but it's more than good enough. Seeing is believing! |
#33
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Faking and expensive tilt-shift lens
On Mon, 09 Feb 2009 17:09:50 -0500, ASAAR wrote:
On Mon, 09 Feb 2009 21:34:29 GMT, John A. wrote: And a pixel IS made of 2x2 photosensors on a Bayer-filtered sensor array. The sensors are arranged something like this: G R B G Together, those four photosensors make up one pixel. Ahhh... But I think I see what you're talking about. That's in a single-exposure Bayer system. In the theoretical four-exposure system we are discussing we would get four three-color synthesized pixels from each 2x2 Bayer array. (Minus a row and a column for the image, I believe, assuming we'd only keep the overlapping portions of the four exposures.) That was what you meant, right? So maybe we both get it, and don't get it. =D Gotcha! But no, the G R B G photo sensors don't make up one pixel. If they did, then a 12mp sensor would have 48 million little silicon RGBG thingies. Some advanced amateurs have been known to physically remove the bayer filter, using powerful solvents to dissolve it. A de-Bayered 12mp sensor then becomes a monochrome 12mp sensor, not a 48mp sensor. In a way, the Bayer filter cheats a bit. The intensity of each colored pixel is calculated by interpolating (demosaicing) the value of the light that it registers as well as that of the differently colored pixels that surround it. The result isn't 100% accurate, but it's more than good enough. Seeing is believing! Dissolving the filter doesn't change the circuitry and firmware. The camera still interprets the 2x2 sensor array as one pixel. |
#34
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Faking and expensive tilt-shift lens
In article , John A.
wrote: On a Bayer-filtered sensor 1/2 pixel = 1 photosite. that's incorrect. You're right. That should have been 1/4 pixel instead of 1/2. I was thinking one-dimensionally. See my other post, though, for further clarification and correction of my thinking. i figured that's what you meant and it's still wrong. |
#35
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Faking and expensive tilt-shift lens
In article , John A.
wrote: Gotcha! But no, the G R B G photo sensors don't make up one pixel. If they did, then a 12mp sensor would have 48 million little silicon RGBG thingies. Some advanced amateurs have been known to physically remove the bayer filter, using powerful solvents to dissolve it. A de-Bayered 12mp sensor then becomes a monochrome 12mp sensor, not a 48mp sensor. In a way, the Bayer filter cheats a bit. The intensity of each colored pixel is calculated by interpolating (demosaicing) the value of the light that it registers as well as that of the differently colored pixels that surround it. The result isn't 100% accurate, but it's more than good enough. Seeing is believing! Dissolving the filter doesn't change the circuitry and firmware. true. The camera still interprets the 2x2 sensor array as one pixel. where did you get that idea? have you been reading sigma/foveon propaganda a bit too much? they are definitely not taken in clumps of four. not only would that would look like ****, but it would resolve a whole lot less than they do now. |
#36
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Faking and expensive tilt-shift lens
On Mon, 09 Feb 2009 22:35:34 GMT, John A. wrote:
Dissolving the filter doesn't change the circuitry and firmware. The camera still interprets the 2x2 sensor array as one pixel. Cutting to the chase, you're rapidly starting to appear dense as a post. Do you not understand that each of the sensels in that 2x2 array is used multiple times in several other 2x2 arrays? Put another way, if you have a sensor containing 4mp photosites, where the Bayer CFA covers 1 meg with red filters, 1 meg with blue filters and the remaining 2 meg sensels with green filters, would you say that it's a 1mp sensor or a 4mp sensor? If you choose to become offended and not reply, thank heaven for small favors. You can read this thread from current and previous rpd forum members discussing this, but I doubt that you'll learn much from it. http://www.burnyourbonus.info/rec.ph...hread2936.html |
#37
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|AX| Faking and expensive tilt-shift lens
John A. wrote:
On Mon, 09 Feb 2009 17:09:50 -0500, ASAAR wrote: On Mon, 09 Feb 2009 21:34:29 GMT, John A. wrote: And a pixel IS made of 2x2 photosensors on a Bayer-filtered sensor array. The sensors are arranged something like this: G R B G Together, those four photosensors make up one pixel. Ahhh... But I think I see what you're talking about. That's in a single-exposure Bayer system. In the theoretical four-exposure system we are discussing we would get four three-color synthesized pixels from each 2x2 Bayer array. (Minus a row and a column for the image, I believe, assuming we'd only keep the overlapping portions of the four exposures.) That was what you meant, right? So maybe we both get it, and don't get it. =D Gotcha! But no, the G R B G photo sensors don't make up one pixel. If they did, then a 12mp sensor would have 48 million little silicon RGBG thingies. Some advanced amateurs have been known to physically remove the bayer filter, using powerful solvents to dissolve it. A de-Bayered 12mp sensor then becomes a monochrome 12mp sensor, not a 48mp sensor. In a way, the Bayer filter cheats a bit. The intensity of each colored pixel is calculated by interpolating (demosaicing) the value of the light that it registers as well as that of the differently colored pixels that surround it. The result isn't 100% accurate, but it's more than good enough. Seeing is believing! Dissolving the filter doesn't change the circuitry and firmware. The camera still interprets the 2x2 sensor array as one pixel. The raw file has the separate bayer parts unmerged. I'm not sure how a half pixel shift would work for increasing resolution... perhaps you'd need to go 1-1/2 or 2-1/2 pixels. -- Paul Furman www.edgehill.net www.baynatives.com all google groups messages filtered due to spam |
#38
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Faking and expensive tilt-shift lens
In article , John A.
wrote: The camera still interprets the 2x2 sensor array as one pixel. where did you get that idea? have you been reading sigma/foveon propaganda a bit too much? they are definitely not taken in clumps of four. not only would that would look like ****, but it would resolve a whole lot less than they do now. It makes more sense when you consider microlenses over multiple sensors, actually. that makes even less sense. |
#39
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|AX| Faking and expensive tilt-shift lens
Paul Furman wrote:
Dissolving the filter doesn't change the circuitry and firmware. The camera still interprets the 2x2 sensor array as one pixel. That's incorrect. The algorithms used to determine pixel values actually look at MORE than a 2x2 array! They try to determine, for example, if an edge runs through a pixel. If it does, they use other parts of the two sides ... outside a 2x2 array ... to try to determine all three RGB values of the pixel. The algortithms are nonlinear .. they do not merely interpolate. They actually GUESS. The raw file has the separate bayer parts unmerged. I'm not sure how a half pixel shift would work for increasing resolution... perhaps you'd need to go 1-1/2 or 2-1/2 pixels. 1/2 pixel increments would work. Doug McDonald |
#40
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Faking and expensive tilt-shift lens
John A wrote:
G R B G Together, those four photosensors make up one pixel. Sorry, your claim is as invalid as your email address. -Wolfgang |
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