8k filming is becoming reality

The CMOSIS digital sensor is now available. It has 48Mpixels and support 8k video at 30fps. Credit: CMOSIS

We are just getting used to 4k television (and 4k has basically been the standard for digital movies) but technology is continue in its progress and is opening the way to 8k video.

8k video (UHDTV) is based on a resolution of 7680x4320 and is the highest definition (as of today of course) for television and digital cinematography that has been defined. 

Why would we want an 8k definition since our eye cannot resolve (at a normal distance) images over 4k definition (this is basically the accepted limit of our eye resolution taking into account the number of cones and rods of the retina)?

Well, there is actually a reason. Our eyes are very seldom standing still. What they do is to continuously scan the environment, and in this scanning the field of view that is covered is larger than the field of view possible to a stationary eye. Hence the image that we feed to our brain is larger than the one optically captured by an eye standing still. The scanning has a very important consequence from a perceptive point of view: it brings to our consciousness the feeling of being part of what we see, a feeling of immersion. This is not what you get by looking at a 4k screen since your brain (because of your eyes scanning) "sees" both the screen and what is around it. Hence you are not feeling as part of the image shown on the screen, even though its definition is equivalent from your point of view ,-) to a real world definition.

By moving onto an 8k definition you can display images that are larger than your scanned field and yet have at least 4k definition in what is captured by your retina. Hence the image you see is indistinguishable from reality AND you feel as being part of it. The video becomes immersive.  To achieve this the screen needs to be so large that the angle of vision exceeds 128° (this is the scanning visual field).

CMOSIS has just released (November 7, 2016) a digital sensor that has 48Mpixel, in a surface that is equivalent (almost) to the 35 mm format (full format) with 7920x6004 pixels. It is priced at 3450€, not cheap, but we know how price evolve over time. (Notice that there are some tricky differences between a sensor resolution and a screen definition...).

The sensor comes without a color filter, hence it provides only black and white information, however a version with an overlaid filter should be available in the coming months.

Interestingly the chip supports an embedded shutter, that can be programmed line by line. This means that one can pick up photons data from odd lines every 1/60 of a second and from even lines every 1/500 seconds. This is equivalent of having to overlaid video cameras working at a 3 stops interval, thus providing a mach broader exposure latitude (HDR). Amazing!

We do not have, yet, any 8k screen at a reasonable mass market price - there was an LG 8k television screen, 88", shown at CES 2016 but no price was indicated, and one from Sharp, 85", at 133,000$, the best on the market are 5k (like the iMac screen or the LG screen).  By the next decade, however, 8k may become what today is the 4k. 8K screens will become affordable but of course we will have to find the space to accommodate them, since it makes sense to have an 8k screen only if they exceed 80". Any smaller will just make that sort of definition useless.

Author - Roberto Saracco

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