As with most other forms of modern entertainment, porn will help embed it as the next format. Like it or not, the porn industry seems to have the power to make or break a format.

Sound slike 4k 3D porn is the way forward. Better learn to duck.

I do think that the extra costs of production might actually work against 4k porn. HD was pretty expensive in terms of set up costs. 4k Will be orders of magnitude more expensive and so I think that porn might not lead this trend.

4k mobile phones on the way - ones which can fin at that resolution, BTW. If they can cram it into a phone....

Above the resolution of retina screens can anyone actually tell? I think that it all becomes a pissing contest and the public are not served any better by it.

Even retina is part of the pissing contest.

I don't agree with that. Retina is about optimum resolution, ie that of a printed page, for the distance it is viewed from.

that's the important bit, the part that can be highly variable. Assigning a number and saying below that number is bad resolution above that number is a waste of a higher resolution.

I have a 32 inch full hd telly I inherited from my grandmother in law and unless, I'm right next to it, I can barely tell the difference between sd and hd. Admittedly, it's not a great telly.

SD doesn't look great on 37" or above. There's a massive difference between it and HD due to the way the scaling works.

It's the same as getting you lovely new 20" monitor and setting it to 640x480. It makes everything bigger and crappy looking.

I thought that retina or any resolution around 300dpi will be beyond the ability of the eye to detect individual pixels. So yes it is part of the pissing contest but it is the lower limit that makes any level above it a waste.