Video Upscaling In Home Theater – The Basics

How video upscaling affects what you see on your TV screen

If you have multiple devices connected to your TV, incoming signals from your satellite, Blu-ray players, or streaming devices 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 necessary.

What Is Video Upscaling?

Video upscaling is a process that mathematically matches the pixel count of an incoming video signal to the displayable pixel count on a TV or video projector. An upscaling processor analyzes the pixel resolution of the source and uses interpolation to create additional pixels. Common display resolutions today include:

If a 4K Ultra HD TV receives and displays a 1080p resolution image 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.

Color chart showing video resolution ranges
Humble Support

Limitations of Upscaling

The upscaling process doesn't actually convert a lower resolution to a higher resolution; it is merely an approximation. Therefore, 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 made directly for the higher resolution.

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, or harsh edges, a video upscaling processor may actually make the image look worse.

When upscaled images are displayed on large screens, 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 or low-resolution streaming content, can deliver mixed results.

How Upscaling Works 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.

Not all video upscaling processors are 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.

Some TVs and video projectors have upscaling processors that are always on, but the video upscaling functions on a DVD player, Blu-ray player, or home theater receiver can be turned off. The upscaling function on the source device will supersede the video upscaling on the TV or video projector.

Video Upscaling and Home Theater Receivers

In addition to performing their role as a source switcher, audio processor, and amplifier, many home theater receivers have 4K upscaling built-in. In some case, they provide image quality adjustment settings similar to what you may find on a TV or video projector.

Video processing on home theater receivers comes in four types:

  • 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. 

Some higher-end 1080p, 4K Ultra HD, and 8K TVs provide some additional color or other image processing regardless of the incoming signal resolution. 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-gamut color information that the TV must process before displaying the images.