4K HD and 4K 16:9 difference

[Rob Ruffo]

Think of what happens to individual pixels when you scale down. In 4K HD a four pixel square is combined into one final pixel. This is not true of the other formats: when combining the 'edge' pixels have to be handled in terms of percentages. Think of 3K HD where 1.5 pixels in each direction get combined into one pixel. 5K HD is much more complex.

If final delivery is 1080p I think I'd shoot 4K HD, unless I needed a wider shot than my widest lens could deliver.

Bob

I most certainly would not. Lens handling is best at 5K HD. Noise is smaller, etc.

 

[James Mustaine]

I'm new to working with R3D files and I'm having an issue. My source files are 5120x2160 but when I export in Premiere using H264, the videos come out 4096x1728 and look really widescreen. How can I get the best quality while maintaining the 16x9 look?

Please help :eek6:

 

[Jeff Kilgroe]

If your clips are 5120x2160, then you shot in 2.35:1 aspect mode or one of the anamorphic modes and it's being de-squeezed. So exporting to 4K, you will get the 1728 pixel height, as that is maintaining the same aspect ratio. If you need 16:9, then you need to crop the sides off the image. Or if everything looks stretched, perhaps you shot in an anamorphic mode when you didn't intend to and instead of cropping, you need to squeeze the image horizontally. Might be helpful if you can post an R3D frame so we can see what you're dealing with.

 

[Gavin Greenwalt]

Just to correct a few things in this thread dug up from the grave:

1) "Quad HD" aka "QHD" is not "Full HD" 1920x1080 x4 (3840x2160). It's "HD" aka the technical definition of HD 1280x720 x4 (2560x1440). If you buy a QHD display that's what you'll get not 4k HD aka UHD (3840x2160)

Oh and because the naming was confusing enough there is also qHD or "quarter HD" which you would think is a quarter of 720 but is actually a quarter of FHD and is 960x540.

Don't even get me started on the naming convention for the UHD derivatives which are even less consistent.

2) There isn't really that much of a practical difference in sharpness between 50% scaling and 48% scaling. It's not badly as extreme as half pixel translations.