Some people have wondered why Arrow and Criterion aren't releasing 4K discs. The answer is that the vast majority of titles they release would not show major benefits of 4K versus blu-ray. I compared the German 4K disc of Oldboy to the Arrow release - which are based on the same scan - and the differences projected onto a 150 inch screen are subtle. Sure - there are differences, but the number of people with set-ups that are able to appreciate these are miniscule. The biggest difference is probably in the English translated subtitles (which are a bit better on the Arrow release). If you want a decent video for home viewing, you don't necessarily need a 4K disc. The scan and the mastering are the most important factors. My old Tartan Video blu-ray of Oldboy looks awful, compared to the new Arrow.