Talk:Bayer filter

Merge between Bayer filter and Bayer sensor

proposed by user:Abdull the 1st mrch 2006

• agree

1. to Bayer filter, bayer sensor is just image sensor + bayer filter. Plus Special:Whatlinkshere/Bayer_filter wins hands down versus Special:Whatlinkshere/Bayer_sensor. There is too many articles on the same subject, see also Demosaicing; RAW image format; Mosaic (digital image); Calculating RGB values... --Marc Lacoste 14:13, 1 March 2006 (UTC)
2. It seems like a good idea, much of the information is duplicated. Henrik 23:23, 7 March 2006 (UTC)

Done --Marc Lacoste 22:46, 19 March 2006 (UTC)

Excess green.

Does anyone know if the 50% green sensor presence is the reason why most people who work with imaging always complain about digital cameras and excessive green? nihil 21:35, 16 August 2007 (UTC)

I would disagree with the premise, to start with, but no. Dicklyon 01:23, 17 August 2007 (UTC)

Well, I've worked with several people involved with desktop publishing, digital imaging and such things. Most of them would start treating images by correcting colour balance, subtracting some green, and then bragging something like "Pff... digital photography, always too much green!". nihil (talk) 19:19, 17 December 2007 (UTC)

I read somewhere (sorry no ref...) that CMYK bayer filters are sometimes used primarily to provide more accurate colour separation for CMYK printing. Interestingly, because the CMYK filter dyes are "paler" than RGB, CMYK filters have higher transmittance than RGB, making them slightly more sensitive. 87.102.115.60 (talk) 12:27, 15 January 2009 (UTC)

The 1976 Bayer Patent illustration shows a YCC (YCbCr?) filter rather than RGB. If my guess is correct, the Luma (Y) sites (requiring no green dye) would be more sensitive than the corresponding Green sites on an RGB filter. If so, the YCbCr colour demosaicing algorithm would need to take this into account to avoid an "excess green" caste. 87.102.115.60 (talk) 12:27, 15 January 2009 (UTC)

@Nihil, such claims about digital photography being too green come down to either personal preference or an incorrect colour temperature setting in the camera (or even a mis-calibrated monitor, if the 'too-green' complaints are always coming from the same person). It is not related to the area of the sensor covered by green filters being greater than that for red or blue. Due to colour correction inside the camera (colour balance as well as primaries adjustment), the amount of light from each sub-pixel in the sensor does not correspond to the amount of red, green and blue in the resulting image. Due to the varying qualities of light and the hit and miss nature of colour temperature setting for most light sources, I suspect that images just as often have a slight magenta cast as green, though when it is a green cast it looks much less visually pleasing. mmj (talk) 07:27, 17 February 2009 (UTC)

A clear filter is not a great "luminance" filter; green is better, and is the preferred embodiment that Bayer points out in his patent. Kodak also a lot on CMY filters; while they allow more light through, they also required bigger matrix coefficients (in the sum of squares sense) to correct the color, resulting in more noise and a net loss of dynamic range usually. I agree with Mmj that the "too green" issue has nothing to do with any of this; that's a color rendering and reproduction issue, not a sensing issue. Dicklyon (talk) 17:47, 17 February 2009 (UTC)

I reverted this edit about color blindness and tetrachromacy: (Except for the 10% who are colorblind. Some humans have 4 color receptors, as well, and thus having filters such as RG1G2B also makes sense (see below), since four positions are available in each 2x2 section.) If there's some true to the idea that the eye's "greater resolving power with green light" is not so in colorblind people, that would be interesting to know and to report (with a source). As to using two different greens, that can be useful for better color accuracy, but there's not evidence that it could have any useful relationship to hypothetical tetrachromacy, espcially since all the images are going to be rendered to a standard RGB space anyway; so unless some source talks about this, we shouldn't either. Dicklyon (talk) 18:11, 13 November 2008 (UTC)

Pixel count

If I have a so-called 1MP color camera, does it have ~1M photosites (0.5M green, 0.25M each red and blue) or does it have 4M photosites? —Ben FrantzDale (talk) 23:32, 12 July 2010 (UTC)

Sorry, it doesn't have 4M of anything; just 1M total of R + G + B pixels. Dicklyon (talk) 02:38, 13 July 2010 (UTC)

Thanks. That's what I figured. While I'm not surprised, it strikes me as deceitful to say that 1e6 photosites => 1e6 pixels since that will display on 3e6 display elements, and since the Nyquist limit for green is that of an 0.5e6-pixel sensor, and is worse for B and R. Either way, thanks. —Ben FrantzDale (talk) 12:28, 13 July 2010 (UTC)

Fabrication

How do sensor manufacturers create millions of precisely-placed color filters aligned to sub-micron precision with the silicon? I can only imagine it's a lithographic process, but wow! Also, what kind of filter is it? Is it a dichroic filter or a conventional color filter? —Ben FrantzDale (talk) 13:59, 4 March 2011 (UTC)

Answer: Color_filter_array#Manufacture_of_the_CFA. —Ben FrantzDale (talk) 14:20, 4 March 2011 (UTC)

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Accidental JPEG artifacts?

The example image of color reinterpolating, looks like it has JPEG compression artifacts in frame 4. Can anyone tell whether that is actually just from color interpolation or whether it may have been accidentally saved to JPEG before being converted to PNG?

--Aij (talk) 21:05, 30 December 2016 (UTC)

No mention of Pure Violet rendered as Blue

In rare instances, violet objects are rendered as blue in digital photography. This is because, while visible light has wavelengths in the range of 400–700 nanometers, blue filters in CFAs will pass violet light (380–450 nm), but the camera records it as blue because it was passed by the blue filter.

You can see it for yourself by printing the Xterm Color Chart and capturing a digital photo of it in bright sunlight. Some of the violets in the printed chart will appear as blue in your photo.

This isn't mentioned or even alluded to in the article. TCav (talk) 21:31, 22 January 2017 (UTC)

Your post is half nonsense, since you can't really make violet by "printing the Xterm color chart". But yes, a true violet would typically be captured as indistinguishable from deep blue, with typical sensor sensitivity curves. Dicklyon (talk) 21:53, 22 January 2017 (UTC)

Did you try it? Print the Xterm color chart on a good photo printer, take it outside, and photograph it with your digital camera(s). Some of the hues that print as violet/purple will be blue in your photos.

In any event, shouldn't this anomaly be mentioned in the wiki? TCav (talk) 14:33, 23 January 2017 (UTC)

TCav, we do not publish original research here. If you have a source, please provide it. Otherwise, I would refer you to tests of colour fidelity conducted in a number of camera reviews or review sites, such as this one, which in my opinion fails to replicate your assertion. Samsara 10:59, 29 July 2019 (UTC)

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Hi folks, I've added "debayering" to the demosaicing section. I'd never heard the term but have now found that it's in common usage with respect to Bayer filtered images. I've also added a new "debayer" redirect page which redirects to the Demosaicing section of this article.

Cadar (talk) 19:22, 31 October 2017 (UTC)