Am I oversharpening
in [Digital Cameras]
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From: Ray Fischer on 8 Jul 2005 02:03 <jennifer.wilson2(a)lycos.com> wrote: > > >Bill Funk wrote: > >> Are you trying to say that each sensor site in an X3 sensor is a >> "pixel"? >> Or, what is it you're trying to say? > >It should be obvious that it takes three sensors, one red, one green, >one blue, to provide the information for a full color output pixel. So >Foveon's full color photosites do correspond to pixels, They do not because they do not have RGB sensors. They have three stacked sensors that are mostly monochrome with a slight bias to red, green, or blue. It takes significant processing to coax out color information. -- Ray Fischer rfischer(a)sonic.net
From: mark on 8 Jul 2005 03:46 JPS(a)no.komm schreef: > In message <1120737139.692894.77290(a)g43g2000cwa.googlegroups.com>, > "mark" <mspan(a)mad.scientist.com> wrote: > > >JPS(a)no.komm schreef: > >> In message <1118723676.491758.184380(a)o13g2000cwo.googlegroups.com>, > >> george_preddy(a)yahoo.com wrote: > >> > >> >13.72MP isn't that common. The Sigmas output 4536 x 3024 pixels images. > >> > >> The Sigma software does; the camera images are only 3.43MP. > > > >The same way debayer software creates 6MP images off the rebel > >sensor... > > Not at all; unlike the 13.7MP output from the Sigma software, 6MP Rebels > actually take a measurement at 6M locations on the sensor. The 13.7MP > Sigma images are merely aliased 3.43MP images softened in upsampling; > the stair-steps get a plush carpet. > -- I'm not going there (with you at least). Bottom line is that when you take raw information from the sensor, bayer sensors give you 1/3 color info on each site, foveon gives you all. Debayer software interpolates the color info to create those humongous large files. Now go and take some pictures! > > <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> > John P Sheehy <JPS(a)no.komm> > ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
From: mark on 8 Jul 2005 06:14 Ray Fischer schreef: > <jennifer.wilson2(a)lycos.com> wrote: > > > > > >Bill Funk wrote: > > > >> Are you trying to say that each sensor site in an X3 sensor is a > >> "pixel"? > >> Or, what is it you're trying to say? > > > >It should be obvious that it takes three sensors, one red, one green, > >one blue, to provide the information for a full color output pixel. So > >Foveon's full color photosites do correspond to pixels, > > They do not because they do not have RGB sensors. They have three > stacked sensors that are mostly monochrome with a slight bias to red, > green, or blue. It takes significant processing to coax out color > information. > You have no idea > -- > Ray Fischer > rfischer(a)sonic.net
From: JPS on 8 Jul 2005 17:41 In message <1120817657.270112.212960(a)g44g2000cwa.googlegroups.com>, "mark" <mspan(a)mad.scientist.com> wrote: >You have no idea Download "IRIS", load some .x3f files, and then maybe you might have an idea. -- <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS(a)no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
From: JPS on 8 Jul 2005 17:57
In message <1120808817.538631.149690(a)o13g2000cwo.googlegroups.com>, "mark" <mspan(a)mad.scientist.com> wrote: >I'm not going there (with you at least). Why not? >Bottom line is that when you >take raw information from the sensor, bayer sensors give you 1/3 color >info on each site, Actually. there is no loss of color coverage at all; the AA filter makes sure that a high percentage of light of all colors hitting anywhere on a particular point of the sensor plane reaches the three color sensors. It is just not possible to record color details above a certain frequency, which is a bit lower than the frequency of luminance detail recorded. We generally can't see color detail at those frequencies anyway, with normal viewing situations. >foveon gives you all. Debayer software interpolates >the color info to create those humongous large files. Foveon does not give all. Foveon gives partial. Foveon has three color channels, but they are not particularly distinct, and the hue resolution can be pretty coarse, especially in the blue/green range. And the blue/green seems to often vary in large, obvious blotches, rather than in a manageable fine dither. Also, none of the current x3f-based cameras have proper aliasing, so they do not give you full spatial information. On the SD9, the capture has a very strong "snap-to-grid" effect, at the pixel level, and this makes the images look artificial to me. There are lots of artifacts that alighn themselves in horizontal and vertical lines, something that does not happen in real vision. If the Sigma cameras had proper AA filters, they would be better, IMO, but a lot of the people drawn to them might not like them, because they like the artificial sharpness of aliasing. You can reproduce the effect easily with any Bayer camera; upsample with bicubic to twice the dimensions of a Sigma image (4536*3024), and then downsize to 2268*1512 with Nearest Neighbor. Voila! Instant SD9 "pop" and staircase effects. -- <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<> John P Sheehy <JPS(a)no.komm> ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>>< |