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 include:
1280 x 720 or 1366 x 768 (720p) 1920 x 1080 (1080i or 1080p) 3840 x 2160 or 4096 x 2160 (referred to as 2160p, UHD, or 4K) 7680 x 4320 (4320p or 8K)
Suppose a 4K Ultra HD TV receives and displays a 1080p resolution image without any upscaling. In that case, the image only fills one-quarter of the screen. To fill the entire screen, the TV must increase the number of pixels accordingly.
Limitations of Upscaling
The upscaling process doesn’t convert a lower resolution to a higher resolution. Instead, it’s an approximation. Therefore, an image that is upscaled to match the number of pixels on a TV screen won’t look the same as an image made 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 make the image look worse. When upscaled images display on large screens, defects present in the source signal are magnified along with the rest of the image. While upscaling DVD and DVD-quality sources to 1080p and 4K can look good, upscaling poor signal sources, such as VHS or low-resolution streaming content, can deliver mixed results.
How Upscaling Works in Home Theater Devices
Several types of components can perform upscaling:
DVD players with HDMI outputs have built-in upscaling so that DVDs 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 DVD and Blu-ray playback. HD and Ultra HD TVs and video projectors have built-in video processors that 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 better perform the task. 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. However, 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 supersedes the video upscaling on the TV or video projector.
Video Upscaling and Home Theater Receivers
In addition to being a source switcher, audio processor, and amplifier, many home theater receivers have 4K upscaling built-in. In some cases, the receivers 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: 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: Analog signals are converted to digital signal signals so that the analog signal 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: Analog and digital video signals can be upscaled to 720p, 1080p, or 4K if needed.
Some high-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 contain HDR and wide-gamut color information that the TV must process before displaying the images.
