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How to Upscale 1080p to 4K – Magic behind the Video Processing

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If you listen to the marketing from TV manufacturers, it seems TVs with 4K resolution will deliver a massive boost in picture quality. And, if you’re lucky enough to actually have a source of real 4K video — one with the same 3,840×2,160-pixel resolution as 4K TVs — you may well be able to see additional detail. Though 4K diaplay are everywhere, real 4K contents are not. Almost all the streaming videos, DVDs, TV broadcast, Blu-ray and other available contents today are 1080p, 720p or even 480p. To watch 1080P or lower resolutions on 4K UHD TVs or screens, there is a step called 4K upscaling. How this works? Go check this post.

What is 4K upscaling?

Upscaling (also upconverting) refers to a process of converting low resolution material into a higher definition – or that’s what it’s purported to do anyway. And 4K upscaling means enlarging the 1080P, 720P or lower-resolution images to near 4K quality to fit the large 4K display. Simply put, 4K displays have 3,840×2,160 pixels, while 1080P videos have 1,920×1,080 pixels. The 4K displays will have four times as much the screen space to fill than 1080P. Therefore, if the 4K TV displays a 1080P video without upscaling, the screen will look like below. For lower resolutions, the image will be smaller.

1080p on 4k tv

How to Upscale 1080p/720p to 4K Video in Just Few Clicks

To upscale video to 4k quaility, there is a video processing technology called interpolation, a process fo creating new pixel points within the range of a discrete set of known pixel points. Simply put, as shown in the above picture, it needs to create more pixel pionts to fill the blank area of a 4K dispay. There are several upscaling algorithms to help achieve this. Here we will introduce you the major consumer-level UHD upscaling algorithms used by 4K TVs, Blu-ray players and other devices: nearest neighbor interpolation, bilinear interpolation and bicubic interpolation. Let’s see how each method works.

1. Nearest neighbor interpolation

Nearest neighbor interpolation, also known as point sampling, is the simplest, fastest and also widely-used method to upscale videos to 4K from 1080P or lower. Unlike the two other methods, it determines the new interpolated pixel by the nearest neighbor point in the input vector or matrix without calculating the value via any weighting criteria or complicated rules. It thus has a lot of blurriness and artifacts.

nearest neighbour interpolation

2. Bilinear interpolation

Linear interpolation is implemented in both X and Y directions (and Z for 3D). And bilinear interpolation is a method that uses the distance-weighted average of 4 nearest known neighboring pixel points to determine the new pixel value. The output pixels are heavily influenced by the neighboring four points. This method is better than the nearest neighbor interpolation but also has visible artifacts and blurring.

bilinear interpolation

3. Bicubic interpolation

In Bicubic interpolation, the interpolated pixel is calculated as the weighted average of 16 (4×4) nearest neighboring points. Generally, bicubic interpolation is more complicated than the other two 4K upscaling methods, but generates more fine details than its bilinear counterpart. Currently, many commonly-used 4k video upscaler programs such as Adobe Photoshop and Corel Photo-paint use Bicubic interpolation as the standard.

bicubic interpolation

So what the easiest way to improve video quality?

To upscale your 1080p to 4K videos with 99% video quality, the key is to get a good 4K upscaling software, which can get this task done. To make it short, Pavtube Video Converter Ultimate is the desirable 4K upscaler for good reasons:

1. Convert video with SD/HD resolution, Blu-ray, DVD to MP4, MOV, M4V, MKV, and other hundreds video formats, and upscale the videos to 4K.
2. Flexible parameter adjustments offers options to upconvert videos to 4K 60fps or 30fps, compress upscaled 4K videos to 30%-70% smaller, etc.
3. Massive video formats, optimized device presets including iDevice, Andorid devices, game console, TVs, Windows operating system, non-linear editing software, and other for you to select with best settings.
4. Rich video editing features allows you to trim the video length, crop video aspect ratio, add image/text watermake, inset external subtitles to it, more features here are beyond your imagination.

Step by step to upscale 4K from 1080P, 720P, SD 540P, 480P

Step 1. Load video files you want to upscale

Click "File" to load the video you to upscale to this software, you also can directly drag or drop the video to this software. Moreover, batch conversion is available here, you are able to upscale several clips at a time.

To download: Pavtube iMedia Converter for Mac

LOAD VIDEOS

Step 2: Choose output file format.

From "Format" bar drop-down list, select H.264 file format by following "HD Video" > "H.264 HD Video(*.mp4)". If you plan to play the upscaling videos on 4K TV, just output H.265 codec which offers the best 4K picture quality with small file size. Or you can driectly follow TVs and output the one you prefer.

Define output file format

Step 3: Adjust output file size as 3840*2160.

Click settings to open "Profile Settings" window, here you can adjust the output file resolution as "3840*2160" by typing the value beside the brackets of "Size(pix)" in the video section.

h.264 settings

Step 4. Start upscaling 4K video

Click Convert and start the video processing. Wait for a while, you can click Open the output folder to locate the generated file. Now you can trasfer the video to your 4K TV for enjoyment, it will not get you down.


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