Talk:Foveon X3 sensor

message: Just in case somehow you missed it (because, yunno.. User:Dicklyon didn't feel like disclosing it), User:Dicklyon holds patents on Foveon X3 sensor technology...
Source: http://www.dicklyon.com/  — Preceding unsigned comment added by 122.61.192.69 (talk) 13:42, 27 December 2014 (UTC)
thread_title:  Massive Conflict of Interest, User Dicklyon 

message: I don't understand the complaint that the article reads like an advertisement.  It seems to me that it gives the relevant technical details on the differences between this sensor and the Bayer-pattern sensors and its advantages and disadvantages.  It also makes a reference to an EDN article that is not wholly complementary.  The fact that it exposits the theoretically superior nature of the chip seems justified to me because it is theoretically superior.  Also, its practical superiority has been shown in the review of the Sigma SD10 in dpreview.com (http://www.dpreview.com/reviews/sigmasd10/), which seems to be a fairly neutral reviewer.
How else could such an article be written to avoid the complaint?
For the record, I don't own a camera with one of these sensors nor do I have any economic interest in the manuracturer. Anoneditor 18:04, 19 December 2006 (UTC)
thread_title:  Don't understand the complaint 

message: There are lots of sources to draw on to fix the article.  Books, Foveon tech papers, other papers, patents.  It shouldn't be hard to find sources for statements, to say which ones are Foveon claims, or someone else's claims, when they are not obviously factual, etc. Dicklyon 18:58, 24 December 2006 (UTC)
replies: text: Landrumkelly, it's unclear to me why you sense emotion here.  Seems like a reasonably dispassionate discussion to me, at least by comparison with other Foveon X3 discussions that I have seen.  Why don't you go ahead and mark with fact tags the items that you see as needing sourcing or correction or removal?  There's no need for you to take on the fixing, just point out the problems.  I can help with the technical expertise and finding sources, but I've avoided doing a lot of editing here because I am not sufficiently neutral on it.  I'll look for sources where requested, correct technical errors, and comment in the discussion, but I'm not going to rewrite the article. Dicklyon 04:53, 31 December 2006 (UTC)

text: One problem here, however, is that few people seem to be paying attention to this article, and nobody really working on it.  So let me point out a few things, and we'll see if we should make some changes.  First, as to the statement about the sharpening filter, I don't buy it; a sharpening filter is not REQUIRED with either Bayer or Foveon type images, but is usually used with both.  So I'd leave that out.  As to an AA fitler not being needed, that's more true; an AA filter is not used in the Sigma cameras, unless you count the anti-aliasing effect of the area over which the microlenses integrate the optical signal; their are plenty of sources to back up the ideas that this is close to the best that can be implemented for an image sensor, unlike the situation with Bayer sensors, though such sources might need considerable interpretation; would you like me to find one?  As to the issue about "effective pixels", that's a tar pit; Askey has his own unique solution; it's probably best to just state what Foveon and Sigma say, and to state what Askey says as an alternative; at present, nothing in the article mentions effective pixels, but the question of how to count pixels is discussed (in a somewhat POV way, though, saying what a buyer needs to do).  Most of the rest of what you had put "it is claimed" on are simple points of physics or optics, that as far as I can see are about right (for example, the depth of absorption of light in silicon is no different in Foveon's silicon than in anyone else's).  Please feel free to ask here, or with tags, about any that you'd like to see sources on. One of the items you questioned already has a reference (on image comparisons) that I added a while back. Dicklyon 06:03, 31 December 2006 (UTC)

text: Landrumkelly, if this topic doesn't deserve an entry, then neither do the CCD or CMOS sensors currently in use in digital photography.  In my view, the X3 is clearly an important innovation in digital photosensor technology as it avoids the color interpolation of the current sensors.  It may not be a perfect product, but it certainly is noteworthy.  Moreover, I find it hard to see how this article falls in the class of "Promotional literature of unproven technological innovations." As to "unproven", the sensor is currently in use in a commercially marketed camera and at least one outside reviewer has demonstrated image sharpness equivalent to current 6MP Bayer sensors.  As to "promotional," though the article may have some technical issues, it isn't as one-sided, as you would expect a promo piece to be.  I think Dicklyon has done some good recent editing on the text and, contrary to your view, I think citations will help. Anoneditor 22:11, 31 December 2006 (UTC)
replies: text: Nobody has suggested removing the topic.  Get over that misconception. Dicklyon 22:50, 31 December 2006 (UTC)
replies: text: I don't recall even hinting that anyone had suggested it.  I was merely taking issue with Landrumkelly's observation.  What prompts you to think I have a "misconception" about this? Anoneditor 23:17, 31 December 2006 (UTC)
replies: text: I was interpreting your earlier statement "I don't think it should be pulled at all" and your more recent "if this topic doesn't deserve an entry" as rebuttals to an imagined suggestion that this topic doesn't deserve an entry or should be removed.  Sorry if I read you wrong. Dicklyon 23:51, 31 December 2006 (UTC)

text: See ref 2 of Anti-aliasing filter (first paragraph of section 26.5).  If you need more, Pratt's book on Digital Image Procesing and Sequin & Thomsett's book on CCDs also make the point, if I recall correctly.  Or see this video lecture on silicon image sensors (at 56:25). Dicklyon 05:37, 1 March 2007 (UTC)
replies: text: Thanks so much.  I'll run them down now that I've reorganized the article. Anoneditor 20:29, 4 March 2007 (UTC)
thread_title: Sources

message: I have substantially reorganized the article for clarity by separating the description of the sensor and its operation from the comparison of the sensor to the Bayer sensor.  Then, I broke that comparison down into three sub-categories.  I've also eliminated the conceptual redundancy and lack of continuity formerly existing in the area of "megapixel" counting and supplied more references and more explanatory text.
However, there are still two matters that are unclear to me, both of which appear in the subsection on "Light gathering and low-light performance." First, Is there really a significant difference in difficulty between demosaicing the Bayer cell output and "matrixing" the Foveon X3 output?  Second, does the "matrixing" really have anything to do with low light performance of the Foveon sensor, as also stated in that paragraph?  The latter seems unlikely but, not being a scientist or engineer in this field, I don't know.  I left those assertions in because they were in the earlier version of the article and there were no complaints about them. I've asked for citations for both. Anoneditor 20:32, 4 March 2007 (UTC)
thread_title: Article Reorganization

message: RenniePet, your mod to the lead is certainly a better conceptualization of how it works; the idea of a sensor responding to primary colors is a common confusion of concepts of sensing versus reproduction of color.  I'd quibble with the word choice "color profiles," however, since that term already has a use in this field.  How about "spectral sensitivities" or "sensitivity curves" or something like that?  Also, on the "blue, green and red", that order was probably inherited from the top-to-bottom sensor order; I recommend the more conventional "red, green, and blue" (with the serial comma, too). Dicklyon 22:18, 25 June 2007 (UTC)
thread_title: Modified lead

message: http://www.imatest.com/docs/print_sharpness.html
"Moire in Foveon sensors is far less bothersome because it's monochrome and because the effective Nyquist frequency of the Red and Blue channels is lower than for Bayer sensors."
http://www.dpreview.com/reviews/SigmaSD9/page23.asp
"However, because the X3 sensor doesn't use a low pass (anti-alias) filter it is able to resolve detail all the way up to Nyquist. Beyond Nyquist the system will alias without any objectionable color moiré. Where a Bayer sensor camera would turn detail beyond Nyquist (such as distant grass texture) into a single plane of blurred color the SD9 will continue to reproduce some individual pixel detail (without color moiré)."
-- Shotgunlee (talk) 16:32, 18 December 2007 (UTC)
replies: text: Those are good sources.  But I reverted due to the statement "...the Foveon X3 sensor with no anti-aliasing filter produces monochrome moiré patterns," since it is slightly wrong on two points: (1) there is actually a pretty effective anti-aliasing filter, as described at Anti-aliasing_filter#Optical_anti-aliasing_filter; (2) whether it produces any aliasing is a function of lots of things; it would be more accurate to say it can produce slight moiré.  And you could check with Norman Koren for what he meant by "the effective Nyquist frequency of the Red and Blue channels is lower than for Bayer sensors" which sounds like he got it backwards. Dicklyon (talk) 16:44, 18 December 2007 (UTC)
replies: text:  (1) We can not say that the foveon x3 sensor has an AA filter. The high fill factor may provide AA effect, but it is certainly not an AA filter. The dpreview link shows strong aliasing. The fill factor of foveon sensor may close to 80%, but not to 100%. (2) What are the things that affect production of aliasing? Why do we need can and slight when the dpreview link shows strong aliasing? I agree on the Nyquist frequency issue. -- Shotgunlee (talk) 18:56, 18 December 2007 (UTC)
replies: text: I just checked which dpreview page you cited, and it's from the SD9, the first camera with X3 technology, which had no microlenses and so had more aliasing.  The microlenses can properly be viewed as an antialiasing filter, since that is part of their purpose in the SD10 and SD14 cameras; the fill factor is about 90%, which is quite effective.  Look at the corresponding SD10 review page; no mention of visible aliasing in the SD10 res chart, even though this is exactly the kind of pattern that would most provoke it.  If you want to add something, this difference between the generations would be worth a mention.  Book refs on Foveon and moire generally say "less prone to moiré" or "reduces" or something to that effect, but in discussing Bayer sensors say "sometimes..." because you don't always get moiré. It would be most appropriate to not reinterpret that Foveon advantage as a negative. Dicklyon (talk) 05:25, 19 December 2007 (UTC)
thread_title:  The Foveon X3 shows monochrome moiré patterns 

message: The article mentions the Polaroid X530 being in production as of March 2008. I know it's hard to prove a negative, but Google suggests that the camera was recalled shortly after release, back in 2005. This news story deals with the problem from a UK perspective, and although Polaroid's UK and US websites have a product information page about the camera, they list no dealers, and I can't find any on Google (I can't even find any on eBay.com). I reckon that the camera is no longer in production or on sale. -Ashley Pomeroy (talk) 18:24, 16 May 2008 (UTC)
replies: text: The camera was re-released after the recall.  I have one, and it works great.  But I don't think they're currently available, unless in some backwater shop some place. Dicklyon (talk) 20:58, 16 May 2008 (UTC)

text: This store claims to have it available for $199.  Get it before it's too late :) Dicklyon (talk) 20:59, 16 May 2008 (UTC)
thread_title:  Polaroid X530 

message: The phrase "Foveon X3" is a registered trademark of Foveon, Inc. and, as such, must be marked in the first instance with the circle-R character.  Since that is in the title of this article and I do not know how to edit titles, can someone who does know how to do this please make the change?  Thanks.
Gilblomdl (talk) 19:41, 14 June 2008 (UTC)
replies: text: Dave, there's no such requirement, and in fact a wikipedia style guideline saying not to:  Wikipedia:TRADEMARK. Dicklyon (talk) 04:01, 15 June 2008 (UTC)
thread_title: Registered trademark

message: I've tried to improve the resolution discussion.  Basically, when people compare resolutions of these two technologies, you have to talk about which kind of resolution.  Furthermore, the resolution of the Foveon sensor is fixed and easy to understand, while the resolution of a Bayer sensor actually varies with the scene; it can achieve full resolution for the photosites it has, but even in the worst case is not much worse than that of a Foveon sensor with the same number of "photodiodes".  —Preceding unsigned comment added by Jcarnelian (talk • contribs) 21:16, 17 June 2008 (UTC)
replies: text: I've reverted your edits.  Several problems that you can work on as put some of the material back:  first, it was all unsourced; especially assertions of opinions of others, such as "Photographers are generally interested in..." should be omitted or sourced; second, do not use excess capitalization in new section headings, and do not add new sections with no sources; third, unsourced statements such as "Both Foveon and Bayer pattern sensors require anti-aliasing filters" that are misleading and essentially contradicted by subsequent text are best avoided; same for "demosaicing can easily achieve full sensor resolution with Bayer patterns."  Please keep these comments in mind as you rework your ideas. Dicklyon (talk) 05:28, 18 June 2008 (UTC)
thread_title: Resolution Again

message: Can someone provide a comparison with 3CCD?  I see lots of text (and bickering on the comment page) about Bayer, but 3CCD is on the market also, in case no one here has noticed. ;) Scott McNay (talk) 06:49, 31 August 2008 (UTC)
replies: text: I'm not aware of any 3CCD digital still cameras.  Do they exist? I seem to remember that Foveon was in the business of producing 3CCD sensors once, but probably for motion picture cameras.  Or maybe my memory is faulty. Anoneditor (talk) 03:36, 1 September 2008 (UTC)
replies: text: I see plenty of digital cameras nowadays that can do short stretches of video, and vice versa for digital camcorders. Scott McNay (talk) 12:25, 1 September 2008 (UTC)
replies: text: I'm talking under correction, but I remember having heard (or deduced) that the 3CCD system causes all sorts of optical deterioration and misalignment, meaning that it's not suitable for high resolution (still photography) For video I guess it's an advantage not to have to do the interpolation in real time, and lowered resolution is not a big concern.FMalan (talk) 16:33, 1 September 2008 (UTC)
replies: text: FMalan, the 3CCD article mentions polarization-dependent color effects, but only to say that the optics must be precise to minimize that.  Anoneditor, the article also mentions still cameras, although I didn't see an obvious reference for this. Scott McNay (talk) 19:23, 1 September 2008 (UTC)
thread_title:  3CCD 

message: This paragraph makes no sense to me:
"Because the depth in the silicon wafer of each of the three layer Foveon X3 sensors is less than five micrometres, it has negligible effect on focusing or chromatic aberration. However, because the collection depth of the deepest sensor layer (red) is comparable to collection depths in other silicon CMOS and CCD sensors, some diffusion of electrons and loss of sharpness in the longer wavelengths occurs."
This isn't like film where emulsion thickness affects sharpness.  The sensor thickness isn't going to have any effect unless the photons or electrons escape from the pixel.  Specifically, the lens is focused on the front surface of the sensor.
Tyrerj (talk) 08:21, 5 August 2010 (UTC)
replies: text: The point is that electrons do escape the pixel, sometimes, if the photon is absorbed a few microns into the substrate and the electron can diffuse away from the nearest n-type collection node to a neighboring one.  It's a small effect, but someone was worrying about depth issues, and that's about all that can be said.  The cited source calls it lateral crosstalk.  Dicklyon (talk) 05:36, 7 August 2010 (UTC)
thread_title:  Sensor Thickness 

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message: Given that there's no need to run antialiasing algorithms with Foveon sensors as compared to Bayer sensors, I would think that one of the big advantages would be lower processing overhead to scan the area and deliver an image.  If so, I would expect that this should be an advantage, and that we would see either less CPU power needed for a camera, or quicker scanning time, (or both) as benefits of the sensor.  Yet nothing like that appears in the advantages section.  Am I misunderstanding, or is an additional benefit sub-section needed?  --Eliyahu S Talk 03:33, 31 July 2018 (UTC)
thread_title:  Less Processing Overhead?