6 ms·

Using a laser to blast away a Bayer filter array from a CCD

145 points by _Microft 5y ago

ruined 5y ago
here's a direct link to the original youtube video explaining and demonstrating the process and results https://youtu.be/y39UKU7niRE https://youtu.be/y39UKU7niRE this is very exciting and i wonder if a similar process could be applied to consumer DSLR/MILC cameras. would love to shoot some high quality video in uv/ir
- opencl 5y ago
  It's certainly possible, there's already a company[1] that sells cameras with this modification performed. And a few cameras that come from the factory with no Bayer filter, like the Leica Monochrom, but all the ones I know of are very expensive. [1] https://maxmax.com/shopper/category/9241-monochrome-cameras https://maxmax.com/shopper/category/9241-monochrome-cameras
- showerst 5y ago
  If you're into lasers at all, les' lab is a great channel. It's really an example of the best part of youtube, just a dude who knows some stuff explaining how things work and showing off shop-made projects.
barbazoo 5y ago
Wow, that's interesting. I didn't know that's how CCDs worked. If I understand correctly, 1/3 of the "pixels" captured the red, 1/3 green, 1/3 blue. Does that mean the sensor now has 3x the resolution it had before?
- _Microft 5y ago
  Often it is even 50% green, 25% red and 25% blue pixels. There are different patterns, though. What you get as "megapixel" number of cameras counts subpixels individually, that is a "10MP" labelled camera does not have 10 million pixels of each color but 10 million subpixels in total. https://en.wikipedia.org/wiki/Bayer_filter https://en.wikipedia.org/wiki/Bayer_filter If you have a device that can output RAWs, you can look at a RAW image using the FOSS photo development program "Darktable". Choose "photosite color" as the "demosaic" filter to show the individual color channel values (and thereby the Bayer pattern of your camera). But yes, after removing the filter, you have three times the number of pixels but you lost color information.
  - falcrist 5y ago
    Since the "pixels" are either formed at every intersection of 4 photosites (overlapping each other) or by interpolating data for each color to include the "missing" photosites (which is effectively the same), the megapixel count should fairly accurately represent both the number of photosites and the number of pixels in the output image. I'm not exactly sure how the edge pixels are treated, but the difference in number between pixels and photosites should be on the order of a few thousand at most.
    - deleted 5y ago
      [deleted]
    - barbazoo 5y ago
      Are you saying that one photosite might be included in more than one pixel and therefore the overall pixel count is roughly equal to the number of photosites?
      - falcrist 5y ago
        I'm saying that each photosite definitely is included in more than one output pixel, and I'm also saying that the number of output pixels should be about the same as the number of photosites. This is obviously capturing less information than if you had a completely separate set of photosites for each pixel, but the megapixel count of cameras is nevertheless accurate. Modern cameras sometimes come with a "pixel shift" function, which uses the image stabilization system to take 4 images each shifted one photosite from the others to construct an image where each pixel contains the information of 4 independent photosites with no sharing between the pixels. The resolution of the final image is the same as a normal image, but the result is much clearer, and far less likely to suffer from blue/red moire.
    - ansible 5y ago
      > I'm not exactly sure how the edge pixels are treated ... It is quite common to have more than the "nominal" number of pixels in a sensor array. So there are extra pixels for the edges.
- pjc50 5y ago
  It always had the same resolution, it's just that beforehand you had to process it down by 3x to get a colour image. What it has now is more range especially in the non visible range.
- barbegal 5y ago
  The reality is that a lot of sensors provide greater resolution than the lens can resolve so the actual spatial resolution barely changes.
- ipsum2 5y ago
  Not specific to CCDs, CMOS sensors also have Bayer filters. Actually, fancy cameras with CCDs skip bayer filters all together by using prisms to split light: https://en.wikipedia.org/wiki/Three-CCD_camera https://en.wikipedia.org/wiki/Three-CCD_camera
  - ulfw 5y ago
    There is not single one on the market and the only one worth mentioning is from 1995 with 0.38MP per sensor. https://en.wikipedia.org/wiki/Minolta_RD-175 https://en.wikipedia.org/wiki/Minolta_RD-175
    - ipsum2 5y ago
      Some modern cameras (mostly delegated to broadcast cameras) still use prism to split light into multiple different sensors. See this 8k 3CMOS camera: https://pro.sony/en_FI/products/4k-and-hd-camera-systems/uhc-8300 https://pro.sony/en_FI/products/4k-and-hd-camera-systems/uhc...
- AceJohnny2 5y ago
  Bayer filters are 50% green, 25% red, 25% blue for consumer devices. The reason is that green actually captures much more of the luminance information, and our eyes have a much better luminance resolution than color resolution. Tangentially, it's why the so-called YUV 420 (chroma subsampling) is so effective, where it's effectively encoding Y (luminance) data for every pixel (in a block of 4), but U/V (chrominance) only for every pair (or quad, someone correct me) of pixels. There are examples online of pictures [1] with their luminance resolution decreased: you can immediately see the pixelation, and of their chrominance resolution decreased: you can barely tell the difference. [1] https://en.wikipedia.org/wiki/Chroma_subsampling#/media/File:Colorcomp.jpg https://en.wikipedia.org/wiki/Chroma_subsampling#/media/File...
  - AceJohnny2 5y ago
    Extra fun fact: Bayer filters were developed by Bryce Bayer at Eastman Kodak, who first researched digital sensors. Despite such a head start, Kodak went on to completely fail the analog-to-digital camera transition. A prime example of the Disruption Dilemma.
    - labcomputer 5y ago
      Because their patents ran out before all the complementary technologies were economically feasible (and CMOS sensors were invented by someone else by that point anyway). It's actually a terrible example of the disruption dilemma. Edit: And there was really no feasible transition path for them anyway. The business depended on skimming a little bit for every photo taken. The main selling point of digital cameras was that you could take unlimited photos at no extra cost. Customers aren't stupid. Even with patents, if you make the camera more expensive to account for the lost revenue on film and processing chemicals, people aren't going to buy it.
  - colonwqbang 5y ago
    YUV/YCbCr 420 means that there is one set of chroma samples (Cb+Cr) for each 2x2 block of luma samples (pixels). Often, the chroma samples fall on pixels in even rows and on even lines. So pixels in odd rows or on odd lines, have to borrow (interpolate) their chroma values from neighbouring pixels.
zokier 5y ago
While neat technique, you could just buy monochrome camera also. Astrophotography community in particular seems to like them so that might be good keyword to search for.
- HeavenFox 5y ago
  True, astrophotographers like monochrome camera because you can prioritize gathering brightness signal over color signal, so you get more detailed photo; you can also use narrowband filter and image under full moon or in inner cities. However, astrophotographers also complain about the price premium of monochrome camera. Given the same sensor, the monochrome version is typically 20% - 30% more expensive than the color version, which is counterintuitive - you don't need to put the Bayer filter on! So if we can perfect the technique to debayer color sensor, the astrophotographer community would be elated.
  - ansible 5y ago
    > the monochrome version is typically 20% - 30% more expensive than the color version, which is counterintuitive... The market for monochrome sensors is very tiny compared to the rest of the commercial products. Every phone now has 2 or more cameras on it, and there are billions of those. Any changes to the manufacturing steps means more setup and effort. Different test procedures, quality control, documentation, etc.. That is all overhead, to be absorbed by a relatively small production volume. I'm surprised it is only a 30% premium, I'd have expected higher actually.
    - spiantino 5y ago
      I'm an avid astrophotographer, and the prices for cooled mono and cooled color cameras are the same. If you compare a dedicated, cooled astro camera to a consumer DSLR then yes, they are more expensive. But apples to apples they are exactly the same price. Actually, looking live the mono version is a bit cheaper: https://optcorp.com/products/zwo-asi6200mc-p https://optcorp.com/products/zwo-asi6200mc-p - color $3999 https://optcorp.com/products/zwo-asi6200mm-p https://optcorp.com/products/zwo-asi6200mm-p - mono $3799
userbinator 5y ago
This reminds me of how the Chinese figured out that a laser could burn through the glass and ablate the glue holding the backs on the newer iPhones, allowing them to be replaced far more easily.

145 points by _Microft 5y ago

here's a direct link to the original youtube video explaining and demonstrating the process and results https://youtu.be/y39UKU7niRE https://youtu.be/y39UKU7niRE this is very exciting and i wonder if a similar process could be applied to consumer DSLR/MILC cameras. would love to shoot some high quality video in uv/ir

opencl 5y ago
It's certainly possible, there's already a company[1] that sells cameras with this modification performed. And a few cameras that come from the factory with no Bayer filter, like the Leica Monochrom, but all the ones I know of are very expensive. [1] https://maxmax.com/shopper/category/9241-monochrome-cameras https://maxmax.com/shopper/category/9241-monochrome-cameras
showerst 5y ago
If you're into lasers at all, les' lab is a great channel. It's really an example of the best part of youtube, just a dude who knows some stuff explaining how things work and showing off shop-made projects.

barbazoo 5y ago

Wow, that's interesting. I didn't know that's how CCDs worked. If I understand correctly, 1/3 of the "pixels" captured the red, 1/3 green, 1/3 blue. Does that mean the sensor now has 3x the resolution it had before?

_Microft 5y ago
Often it is even 50% green, 25% red and 25% blue pixels. There are different patterns, though. What you get as "megapixel" number of cameras counts subpixels individually, that is a "10MP" labelled camera does not have 10 million pixels of each color but 10 million subpixels in total. https://en.wikipedia.org/wiki/Bayer_filter https://en.wikipedia.org/wiki/Bayer_filter If you have a device that can output RAWs, you can look at a RAW image using the FOSS photo development program "Darktable". Choose "photosite color" as the "demosaic" filter to show the individual color channel values (and thereby the Bayer pattern of your camera). But yes, after removing the filter, you have three times the number of pixels but you lost color information.
- falcrist 5y ago
  Since the "pixels" are either formed at every intersection of 4 photosites (overlapping each other) or by interpolating data for each color to include the "missing" photosites (which is effectively the same), the megapixel count should fairly accurately represent both the number of photosites and the number of pixels in the output image. I'm not exactly sure how the edge pixels are treated, but the difference in number between pixels and photosites should be on the order of a few thousand at most.
  - deleted 5y ago
    [deleted]
  - barbazoo 5y ago
    Are you saying that one photosite might be included in more than one pixel and therefore the overall pixel count is roughly equal to the number of photosites?
    - falcrist 5y ago
      I'm saying that each photosite definitely is included in more than one output pixel, and I'm also saying that the number of output pixels should be about the same as the number of photosites. This is obviously capturing less information than if you had a completely separate set of photosites for each pixel, but the megapixel count of cameras is nevertheless accurate. Modern cameras sometimes come with a "pixel shift" function, which uses the image stabilization system to take 4 images each shifted one photosite from the others to construct an image where each pixel contains the information of 4 independent photosites with no sharing between the pixels. The resolution of the final image is the same as a normal image, but the result is much clearer, and far less likely to suffer from blue/red moire.
  - ansible 5y ago
    > I'm not exactly sure how the edge pixels are treated ... It is quite common to have more than the "nominal" number of pixels in a sensor array. So there are extra pixels for the edges.
pjc50 5y ago
It always had the same resolution, it's just that beforehand you had to process it down by 3x to get a colour image. What it has now is more range especially in the non visible range.
barbegal 5y ago
The reality is that a lot of sensors provide greater resolution than the lens can resolve so the actual spatial resolution barely changes.
ipsum2 5y ago
Not specific to CCDs, CMOS sensors also have Bayer filters. Actually, fancy cameras with CCDs skip bayer filters all together by using prisms to split light: https://en.wikipedia.org/wiki/Three-CCD_camera https://en.wikipedia.org/wiki/Three-CCD_camera
- ulfw 5y ago
  There is not single one on the market and the only one worth mentioning is from 1995 with 0.38MP per sensor. https://en.wikipedia.org/wiki/Minolta_RD-175 https://en.wikipedia.org/wiki/Minolta_RD-175
  - ipsum2 5y ago
    Some modern cameras (mostly delegated to broadcast cameras) still use prism to split light into multiple different sensors. See this 8k 3CMOS camera: https://pro.sony/en_FI/products/4k-and-hd-camera-systems/uhc-8300 https://pro.sony/en_FI/products/4k-and-hd-camera-systems/uhc...
AceJohnny2 5y ago
Bayer filters are 50% green, 25% red, 25% blue for consumer devices. The reason is that green actually captures much more of the luminance information, and our eyes have a much better luminance resolution than color resolution. Tangentially, it's why the so-called YUV 420 (chroma subsampling) is so effective, where it's effectively encoding Y (luminance) data for every pixel (in a block of 4), but U/V (chrominance) only for every pair (or quad, someone correct me) of pixels. There are examples online of pictures [1] with their luminance resolution decreased: you can immediately see the pixelation, and of their chrominance resolution decreased: you can barely tell the difference. [1] https://en.wikipedia.org/wiki/Chroma_subsampling#/media/File:Colorcomp.jpg https://en.wikipedia.org/wiki/Chroma_subsampling#/media/File...
- AceJohnny2 5y ago
  Extra fun fact: Bayer filters were developed by Bryce Bayer at Eastman Kodak, who first researched digital sensors. Despite such a head start, Kodak went on to completely fail the analog-to-digital camera transition. A prime example of the Disruption Dilemma.
  - labcomputer 5y ago
    Because their patents ran out before all the complementary technologies were economically feasible (and CMOS sensors were invented by someone else by that point anyway). It's actually a terrible example of the disruption dilemma. Edit: And there was really no feasible transition path for them anyway. The business depended on skimming a little bit for every photo taken. The main selling point of digital cameras was that you could take unlimited photos at no extra cost. Customers aren't stupid. Even with patents, if you make the camera more expensive to account for the lost revenue on film and processing chemicals, people aren't going to buy it.
- colonwqbang 5y ago
  YUV/YCbCr 420 means that there is one set of chroma samples (Cb+Cr) for each 2x2 block of luma samples (pixels). Often, the chroma samples fall on pixels in even rows and on even lines. So pixels in odd rows or on odd lines, have to borrow (interpolate) their chroma values from neighbouring pixels.

zokier 5y ago

While neat technique, you could just buy monochrome camera also. Astrophotography community in particular seems to like them so that might be good keyword to search for.

HeavenFox 5y ago
True, astrophotographers like monochrome camera because you can prioritize gathering brightness signal over color signal, so you get more detailed photo; you can also use narrowband filter and image under full moon or in inner cities. However, astrophotographers also complain about the price premium of monochrome camera. Given the same sensor, the monochrome version is typically 20% - 30% more expensive than the color version, which is counterintuitive - you don't need to put the Bayer filter on! So if we can perfect the technique to debayer color sensor, the astrophotographer community would be elated.
- ansible 5y ago
  > the monochrome version is typically 20% - 30% more expensive than the color version, which is counterintuitive... The market for monochrome sensors is very tiny compared to the rest of the commercial products. Every phone now has 2 or more cameras on it, and there are billions of those. Any changes to the manufacturing steps means more setup and effort. Different test procedures, quality control, documentation, etc.. That is all overhead, to be absorbed by a relatively small production volume. I'm surprised it is only a 30% premium, I'd have expected higher actually.
  - spiantino 5y ago
    I'm an avid astrophotographer, and the prices for cooled mono and cooled color cameras are the same. If you compare a dedicated, cooled astro camera to a consumer DSLR then yes, they are more expensive. But apples to apples they are exactly the same price. Actually, looking live the mono version is a bit cheaper: https://optcorp.com/products/zwo-asi6200mc-p https://optcorp.com/products/zwo-asi6200mc-p - color $3999 https://optcorp.com/products/zwo-asi6200mm-p https://optcorp.com/products/zwo-asi6200mm-p - mono $3799

userbinator 5y ago

This reminds me of how the Chinese figured out that a laser could burn through the glass and ablate the glue holding the backs on the newer iPhones, allowing them to be replaced far more easily.