Sigma/Foveon Questions
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From: nospam on 20 Apr 2010 14:30 In article <MPG.26380d741bc11bf298c2a7(a)news.supernews.com>, Alfred Molon <alfred_molon(a)yahoo.com> wrote: > Bayer does not capture the luminance at the pixel level, period. However > the green channel is a good estimate of luminance and half of the pixels > in a Bayer sensor are green, which is why the performance of a Bayer > sensor is not as abysmal as the lack of 2/3 of the colour information > would imply. it's a good estimate but bayer does better than that by using the red and blue pixels too.
From: Alfred Molon on 19 Apr 2010 01:43 In article <180420101508449021%nospam(a)nospam.invalid>, nospam says... > In article <MPG.2635a0118e4698e198c2a2(a)news.supernews.com>, Alfred > Molon <alfred_molon(a)yahoo.com> wrote: > > > In article <180420100922201916%nospam(a)nospam.invalid>, nospam says... > > > > > wrong. every pixel captures luminance. > > > > No. In a Bayer sensor every pixel captures either the red, green or blue > > channel. This is NOT luminance. > > it's one component of the luminance, with the remaining two later > calculated. So you agree that in a Bayer sensor the luminance is not captured in each pixel. > > > > To properly capture luminance at each pixel you need the full colour > > > > information at each pixel. > > > > > > wrong, as bayer has proven. > > > > No - you are wrong. > > so all of the zillions of photos that very accurately reproduce the > subject all have completely bogus luminance? how can that be? The accuracy is not that high - there are some errors which have the effect of reducing the effective resolution. -- Alfred Molon ------------------------------ Olympus E-series DSLRs and micro 4/3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site
From: nospam on 19 Apr 2010 01:51 In article <MPG.26360be21e9fe77b98c2a3(a)news.supernews.com>, Alfred Molon <alfred_molon(a)yahoo.com> wrote: > > > > wrong. every pixel captures luminance. > > > > > > No. In a Bayer sensor every pixel captures either the red, green or blue > > > channel. This is NOT luminance. > > > > it's one component of the luminance, with the remaining two later > > calculated. > > So you agree that in a Bayer sensor the luminance is not captured in > each pixel. don't twist what i said. luminance is measured at every pixel, even though only one component is actually captured. the other two are calculated. the system works, and it works well. > > > > > To properly capture luminance at each pixel you need the full colour > > > > > information at each pixel. > > > > > > > > wrong, as bayer has proven. > > > > > > No - you are wrong. > > > > so all of the zillions of photos that very accurately reproduce the > > subject all have completely bogus luminance? how can that be? > > The accuracy is not that high - there are some errors which have the > effect of reducing the effective resolution. it's actually very high, that's why photos look as good as they do. can you point to a unbiased test (i.e., not from foveon) that shows otherwise?
From: Martin Brown on 20 Apr 2010 03:06 nospam wrote: > In article > <29295e42-9297-4868-bbd6-43ba857791fc(a)u37g2000vbb.googlegroups.com>, > Bubba <digitalrube(a)yahoo.com> wrote: > >>> red flare is not aliasing, however, the dp1/dp2 series have a red dot >>> problem, although the latest versions have minimized it. >> If you're not yanking my chain and are serious when you use the term >> "red flare"--which no one on the threads I've started has even >> acknowledged exists-- > > this is the problem to which i refer: > > <http://www.testiweb.com/images/jpg/digital_cameras/Sigma%20dp1/Jpg%2095 > 0x%20or%20lower/foveon_flares_2_SDIM0025_950x.jpg> > <http://www.testiweb.com/images/jpg/digital_cameras/Sigma%20dp1/Jpg%2095 > 0x%20or%20lower/foveon_flares_3_SDIM0043_950x.jpg> > <http://raist3d.typepad.com/files/sigmanotoksunclouds.jpg> I am probably in a minority of one here, but I think the Foveon flare adds to the first of these images rather than detracts. But the fact still remains that the sensor is pretty dire when faced with extreme highlights in the field of view. > >> In a $500-$600 range, is a camera available that will lessen or do >> away with red flare without the purchase of additional lenses or >> filters? > > plenty of them. You are still going to have to define what *you* mean by "red flare" apart from some dopey bunch of software guys in the UK no-one else uses the term. > >> So if these wacky Sigma cameras have no zoom except digital, but if >> their partisans swear by the cameras' sensors' ability to get rid of/ >> diminish this flare, that makes me ask Why would these people not want >> another P&S camera that *has* optical zoom (or at least the ability to >> attach a lens) AND a CMOS sensor. > > they're delusional. There are a handful of cases where the Foveon sensor might give a better image and one of those is when photographing fine black detail on saturated red or blue flowers. Rest of the time it is all marketting. I don't think the OP can be helped. He will not help himself by posting an image to demonstrate the problem that he thinks he has. It is quite possible that the thing he calls red flare is actually a decoding artefact in the software that he happens to use! Regards, Martin Brown
From: nospam on 20 Apr 2010 04:25
In article <pnczn.155939$y13.49322(a)newsfe12.iad>, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote: > There are a handful of cases where the Foveon sensor might give a better > image and one of those is when photographing fine black detail on > saturated red or blue flowers. Rest of the time it is all marketting. black detail on saturated colours should be ok with bayer because there's a big luminance difference and bayer generally gets that right. where bayer has a problem is with two different saturated colours, such as red/blue, especially if the luminance is similar. the human eye can't handle that particularly well either. |