Video Upscaling – The Basics

How video upscaling affects what you see on your TV screen

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With the abundance of content sources to view on your TV, it is important to note that not all those sources have the same video resolution. Incoming signals from broadcast/cable/satellite/DVD/streaming, etc... may not have the same video resolution that your TV is capable of displaying. In order to provide the best viewing quality for different sources, video upscaling may be needed.

What Video Upscaling Does

Video upscaling is a process that mathematically matches the pixel count of an incoming video signal to the displayable physical pixel count on a TV or video projector, which may be:

The way this is typically done is an upscaling processor analyzes the pixel resolution of the source and, using interpolation "creates" additional pixels or duplicates the pixels to match the number of pixels on the screen.

4K Resolution Comparison Chart
Image courtesy of OPPO Digital

As shown in the illustration above, if a 4K Ultra HD TV receives a 1080p resolution image and displayed it without any upscaling, the image would only fill one-quarter of the screen. To fill the entire screen, the TV has to increase the number of pixels accordingly.

What Upscaling Doesn't Do

The upscaling process does not "magically" convert a lower resolution to a higher resolution – it is merely an approximation. This means an image that is upscaled to match the number of pixels on a TV screen will not look the same as an image that is native to that higher resolution in the first place.

Although upscaling is designed to improve the image quality of lower resolution video signals it isn't always effective. If a signal contains additional embedded artifacts, such as excessive video noise, poor color, harsh edges, or is otherwise unstable, a video upscaling processor may actually make the image look worse. This is especially an issue when upscaled images are sometimes displayed on large screens. This means defects already present in the source signal are magnified, along with the rest of the image.

While upscaling DVD and DVD-quality sources to 1080p and even 4K can look pretty good, upscaling poor signal sources, such as VHS (especially recordings made in the EP speed, analog cable, or low resolution streaming content) can deliver mixed results.

How Upscaling Is Executed In Home Theater Devices

Upscaling can be performed by several types of components.

  • DVD players that have HDMI outputs also have built-in upscaling so that DVDs will look better on an HD or 4K Ultra HD TV or video projector.
  • All Blu-ray Disc players have built-in video upscaling to provide better quality playback of standard DVDs.
  • All Ultra HD Blu-ray players provide video upscaling for both DVD and Blu-ray playback.
  • HD and Ultra HD TVs and video projectors have their own built-in video processors that can perform video upscaling functions.

However, one thing to keep in mind is that video upscaling processors are not all created equal. Although your TV may provide video upscaling, your DVD or Blu-ray Disc player may be able to perform the task better. By the same token, your TV might do a better job of video upscaling than your home theater receiver (more on that in the next section).

Except for TVs and video projectors whose upscaling processors are always on, the video upscaling functions in a DVD, Blu-ray Disc Player or home theater receiver can be turned off, allowing the native resolution signals coming from each source to be untouched until they reach the TV.

If you leave the upscaling function your source devices on they will supersede the video upscaling in the TV or video projector. For example, if you have a 1080p TV and the signals coming are either native 1080p or previously upscaled to 1080p - the TV becomes neutral.

This also applies to 4K Ultra HD TVs – if the incoming signal is native 4K or already upscaled to 4K.

Video Upscaling and Home Theater Receivers

Many home theater receivers, in addition to performing their role as a source switcher, audio processing, and amplifier, may also provide built-in video upscaling, and, in some case, provide image quality adjustment settings similar to what you may find on a TV or video projector.

Video processing on home theater receivers may take four forms:

  • Video pass-through only: All video from devices connected to the receiver are routed through the receiver to the TV without any video upscaling or processing. 
  • Analog to HDMI conversion: All analog signals are converted to digital signal signals so that they can be sent from the receiver to the TV via HDMI cable. However, no further video processing or upscaling is performed. 
  • 1080p to 4K upscaling: All 1080p sources (Blu-ray or streaming) are upscaled from 1080p to 4K for better results when connected to a 4K UHD TV. Analog to 1080p or 4K upscaling may, or may not be provided. 
  • Analog and Digital Video Upscaling: All analog and digital video signals can be upscaled to 720p, 1080p, or 4K if needed. 

More To Consider

If you have a setup that includes a 1080p or 4K Ultra HD TV or video projector and you have source device or a home theater receiver that can also perform upscaling functions, you have to decide which does the better job (in other words what looks best to you). Once you have decided, set the video output resolution of your source components accordingly.

There are some exceptions to the rule as higher-end 1080p, 4K Ultra HD, and 8K TVs provide some additional color or other image processing no matter what the incoming signal resolution is. For example, with the Ultra HD Blu-ray Disc format, as well as some 4K streaming sources, the content may also contain HDR and Wide Color gamut information that the TV must process before displaying the images.