Before we dive into the difference between 1920 X 1080 and 4K resolution, let’s make sure we all have a correct understanding of the term “resolution”. Resolution represents the dimensions of a video in pixels. So a resolution of 1920 X 1080 means that the video is 1920 pixels wide and 1080 pixels high (remember to walk before you fly – width x height). “HD” really only applies to two specific resolutions: 1920 X 1080 and 1280 X 720 pixels.
D (Standard Definition). Pixel Size: 640 x 480 (also know as: 480p)
HD (High Definition) Pixel Size: 1280 x 720 (also know as: 720p)
Full HD Pixel Size: 1920 x 1080 (also know as: 1080p)
Where does 4k fit in?
“4K” is the thing a lot of TV and camera manufacturers are throwing around as “The Next Big Thing.” Cameras as small and inexpensive as the Panasonic G7, to much larger systems like the Sony FS7, all include 4K shooting in their list of specifications.
What isn’t particularly clear is just what “4K” means. The answer: it depends.
Strictly speaking, 4K refers to a video frame that’s at least 4,000 pixels wide. However, as a video editor, the type of so-called 4K footage you will likely encounter with a 16:9 aspect ratio is “4K” standard for TVs, which actually stops just short of being an actual 4000+ pixels wide. Take your good friend 1920 X 1080, and times the height and with by 2. What do you get: 3840 X 2160 pixels! This preserves the beloved aspect ratio of 16:9, which is the same aspect ratio for HD TVs. Of course, “4K” sounds a lot sexier, and easier to remember, which is why manufacturers go ahead and stick that logo on their boxes.
Photo Cred: the Video Effect
Editing 4K Video Footage.
At this point, you might be thinking: “SWEET! Should I be shooting in 4k?”
That depends. YouTube supports 4k video but will compress the file so much on upload that you might not see the benefits. Facebook still doesn’t support 4k video. And if you’re sending video files to clients, they might not appreciate a massive, computer-busting 1TB 4K .mp4 file showing up in their inbox.
I often shoot in 4k even when I know I’m going to export the finished project in 1080p. Why? Because I can simulate a multi-camera shoot easily. Either cutting between different crops, or using keyframes to animate movements, such as doing a two-minute zoom in on singer from wide to close-up. The motion is almost imperceptible, no way to accomplish that with most cameras. If you want to “cut” from one crop to another, just Razor the footage at the point where you want to change the scale/position.
Setting up your sequence: manually create a 1080p sequence. For instance, AVCHD > 1080p30. Drop your 4K clip into the sequence. Select clip and look at Effect Controls and you will see that it says 100% for scaling. At this point, if you zoomed in at all, you would actually lose quality, as if working with a 1080p source. So now right-click and select Set to Frame and you will notice that Scale drops to 50%.
This means that Premiere is now using the full original 3840×2160 pixels as a source (rather than pre-scaling to 1080 to match sequence) and is scaling that down to 50% to fit it in the 1920×1080 frame. Therefore, if you zoom (scale) the image up to anything between 50-100%, you will lose no quality at all. Every pixel in the 1920×1080 frame is being pulled from the 3840×2160 source, no pixels needing to be duplicated (blown-up).
Note that a 4k UHD image is the same as 4 full HD images. At 100%, you will be seeing one “quadrant” of the original, in 1:1 pixels, so quality would really be identical to an original 1080p image. Only once you scale past 100% would it technically start to degrade, and really you might get to 115-120% and it could still look good depending on clarity/quality of original footage.
The sample image above is at 3840 X 2160, made from 4 HD images. Try it with the above directions in a 1080p sequence to visualize what’s happening. Set to Frame, then scale to 100%, then position image so that just one of the 4 images fills the screen. That is the 1:1 pixel mapping and quality right there.
Tip: If you have several clips on the timeline, you can multi-select them and apply Set to Frame on all at once.
In conclusion, 4K video is pretty AWESOME (even if you export this final project to 1080p).
Check Out the 4k Video of Iceland (which I consider to be one of the most beautiful places on earth)
Even if you’re watching this video on a 1080p monitor, you can still get most of the benefit of 4K. That’s because 4K cameras are capturing 2 green, 1 blue, and 1 red pixel so each pixel isn’t a full color pixel. Displays and HDTVs on the other hand render full RGB. When you merge 4 pixels (2×2) from a 4K stream, it produces a full RGB 1080P image which renders perfectly on a 1080P monitor.
I hope you’ve enjoyed this article. Please comment below with your thoughts, insights and opinions!