September 5, 2016 at 4:38PM

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Is Downresing From 4k to 1080 Actually Good?

I've been working with the a6300 for two months now. I had a friend and people on different forums tell me that down resing to 1080 looks just as good if not better than rendering in 4K. I have not found that to be the case. My 4k renders always look better than the 1080 renders. Now, there are projects where I will downres because it's going straight to IG. But as far as wanting the best resolution quality, 4k always looks better to me (I've even been wearing my glasses). The 1080 doesn't look bad, but it doesn't look as good as 4k. Can anyone here explain why downresing to 1080 doesn't look as good? And why do some people actually think it does look as good?

9 Comments

Obviously 4K is much better than 1080p!

People who claim 1080p is better probably do not shoot in 4k! :p

September 5, 2016 at 6:59PM, Edited September 5, 7:00PM

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Cary Knoop
Member
2507

A lot depends on how you down-rez your footage and the format you are using.

Good 4K footage will retain more image resolution than down-rezzed 1080p footage, but 4K 4:2:0 footage properly down-rezzed becomes 1080p 4:4:4 footage that can look better than the original 4K 4:2:0 footage because the chroma-resolution of the down-rezzed footage is the SAME as the luma resolution.

My favorite method of down-rezzing 4K to 1080p is to use the Cineform CODEC which uses wavelet compression ( which retains as much 4K detail as it can in it's 1080p format ) and is designed to retain all of the color information from the 4K 4:2:0 footage when it converts it down to 1080p 4:4:4 footage.

September 5, 2016 at 10:57PM

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Guy McLoughlin
Video Producer
30354

>> " 4K 4:2:0 footage properly down-rezzed becomes 1080p 4:4:4 footage that can look better than the original 4K 4:2:0 footage because the chroma-resolution of the down-rezzed footage is the SAME as the luma resolution."

Sorry Guy but I have to disagree with you on that.

1080p 4:4:4 is better than 1080p 4:2:0 (although the difference is hard to see in natural images) but it is not even close to 4K 4:2:0.

Cary Knoop

September 6, 2016 at 10:01AM

Thanks Guy. I was looking for a technical/scientific explanation that I could piggy back off and research with the proper terms (4:2:0, chroma resolution, etc). I see Cary disagrees. I don't know enough on the subject to pick a side. Also, I will try your process with Cineform. The two ways I'vs been doing it are clearly not good enough to my eyes.

Don Way

September 11, 2016 at 4:08PM, Edited September 11, 4:08PM

>>>1080p 4:4:4 is better than 1080p 4:2:0 (although the difference is hard to see in natural images) but it is not even close to 4K 4:2:0

The difference is most visible with fine diagonal or curved lines, where the footage with the lower color resolution will look aliased or "jaggy". While the 4K 4:2:0 footage contains the same amount of color information as the 1080p 4:4:4, it's spread out over 4 times the luma area, so you will see aliasing and "jaggy" color edges in 4K that you won't see in the 1080p 4:4:4 footage.

September 6, 2016 at 1:52PM, Edited September 6, 1:53PM

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Guy McLoughlin
Video Producer
30354

That's standard practice with our FS5. Shoot everything in 4k and work in 1080. Comparing them side by side, its not a dramatic difference unless you pixel peep, but being able to push in on any shot, especially interviews, has been a big game changer.

September 7, 2016 at 9:48PM

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Josh.R
Motion Designer/Predator
862

It all comes down to what resolution your display and your viewing distance. 480p video on my iphone looks as sharp as 4K on my 27" monitor. If you're watching 4K on a 1080p display, you are not actually seeing a difference vs 1080p content.

September 9, 2016 at 7:02PM

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Dave
80

Yes it is... Wait! This is also one of those questions which have the answer "it depends".

If you know that you audience has full HD monitors and TVs and projectors etc. only then it does make sense.
BUT (and this is where the future is an important factor) if you know, that your audience has or will have the ability to watch native 4K (or UHD, whatsoever), it's better to not downscale it.
Because then you have a 4K image downscaled to 1080 upscaled by the TV to 4K with some anti-aliasing filters.

Yes. An image shot in 4K watched on a 1080 monitor looks way better than a 1080 image on a 1080 monitor from the same / a similar camera. But higher hardware resolution is always better because then you have realy more information. If you just downscale 4K it's still the same info as 1080 but it looks nicer because higher res images on smaller res monitors look always sharper.

Also, if you scale it to 1080, you can punch in and out so you get multible shots out of one. That's maybe the most important aspect of all of this discusion if you are not interrested into sharpnes and detail ishues.

In conclusion:
It does make sense. But only, if you cannot watch it in full resolution or if you need multible shots.
Most of the time, the higher resolution on the higher res screen is the best option because of aliasing and moire.

September 12, 2016 at 1:05PM

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Eric Halbherr
Director, DP, Editor, Creative Storyteller
2259

Are you talking about shooting 1080 p and rendering it to 4k or 4k and rendering it to 1080p?

For the a6300 I am really surprised that you would think the 4k is better than the hd resolution.
I have the a6500 and found the 4k internal recording shooting modes to be very restrictive in terms of where it results in acceptable images.

Basically the 1080p vs 4k debate on that camera comes down to bitrate and chroma sampling. The camera has a low bitrate for 4k recording at around 100Mbs peak. It has to throw out LOTS of information to make that work and much of that is chroma data. So while you have more pixels there is less color information. Add on top of that there is an 8 bit limitation.

So think of it this way in a rgb 4:4:4 image you have 8 bits for each channel of 24 bits of color information per pixel.

in 4:2:0 you have 8:4:0 bits so for any individual pixel you only have 12 bits of color information. On top of that you then need to compress that data and there is a lot of data in a 4k image.

For the HD resolution it can record at 50Mbit, 4:2:2 . That is 16 bits available for each pixel. It records at 1/2 the data rate but only has to encode 1/4 of the pixel information. It is far less compressed, which can give you smoother color transitions on top of starting with much more data to describe colors.

So for internal recording you get smoother colors with less compression. For me the chromatic bleed on the edge of colorful colors against neutrals was just to distracting. and it only became worse as images got darker.

If you can use an external recorder and can have 4:4:4 at a high low compression then 4k is the obvious choice. When you are recording in camera HD is easier to work with then rescale to 4k for final deliverable.

March 28, 2017 at 3:41PM

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Joseph Slomka
Color Scientist - Acquisition through archival
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