Wednesday, October 01, 2014
A Closer Look at iPhone 6 and 6 Plus Cameras
Chipworks publishes a more detailed report on iPhone 6 and 6 Plus cameras, both front and rear. All cameras have stacked sensors made by Sony. The front FaceTime camera has 2.2um pixels (up from 1.75um in iPhone 5s) and features an interesting CFA pattern:
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Question please : Why the peripheric pixels are brighter on the photo ?
ReplyDelete-yang ni
Color filters in the periphery (probably) lie on top of metal shielded, optical black pixels, with almost 100 % reflection. Color filter in the active area lie on top of the absorbing silicon pixels with ideally 0 % reflection. So it was even better if they looked completely black.
DeleteThanks Albert !
DeleteBut when you look at the auto-focus pixels inside the array, they are also brighter than others. I don't think that these pixels are shielded by a top metal.
-yang ni
The PD pixels would be 1/2 shielded by metal, so they would also look bright under the microscope illumination.
DeleteSo, why not using dark shielding? I think it could reduce sensor flares by reduce light reflected by optical black shielding.
DeleteAbsorptive black coating is much thicker than a reflective metal layer blocking the same amount of light. Metal layers are also much cheaper, most times they even come free of charge. An additional layer of optical black is costly, but for demanding applications quite worth it. The darker your dark pixels become, the better they can be used for correction in the presence of brigh light sources. Having a mirror finish to the area surrounding the imaging area is not good for stray light performance, either.
DeleteI hope that many sensor designers read this, so please, consider it for your next design. It makes the life of a camera designer much easier.
J.H.
Looks like 4 small microlens on 1 color filter.
ReplyDeleteWhy do they needs 4 small microlens? Have difficulties to make one large and thick microlens of 2.2um pixel size?
Maybe 1.1u pixels x 4 with analog binning and/or short/long exposure per line for real time HDR?
DeleteAgree, this is the likely case, so this is actually a ~5MP sensor that is only operated in binning or HDR modes.
DeleteJust my guess. This may be an improved way of doing “binning spatially varying exposure” to achieve HDR. One line of the 2-line pair is for long exposure and the other for short exposure, such as described in Sony’s 2013 ISSCC paper & slides.
ReplyDeleteThere can be four exposures. Check this patent application, US2013/0057743.
DeleteM. W.
the motion artifacts are even worse compared to the frame based HDR of the rear camera. Dont understand the fuss about the quad binning pixels and HDR. The HDR quality isnt any good
ReplyDeleteLook like Bayer filter to me
ReplyDeleteBut for each colour there are four pixels so actually its RRGG.
Delete