A video scaler is a device for converting video signals from one size or resolution to another: usually "upscaling" or "upconverting" a video signal from a low resolution (e.g. standard definition) to one of higher resolution (e.g. high definition television).

Video scaler devices can be found embedded in:

  • Computer monitors
  • Scan conversion devices
  • Televisions
  • Video editing and broadcasting equipment
  • Other audio/visual devices

Video scalers can also be a completely separate box, often providing simple video switching capabilities. These units are commonly found as part of home theatre or projected presentation systems. Home theatre uses might include converting a standard definition DVD or video game signal into high-definition for display on an LED, LCD or plasma television while obtaining the best image quality possible. Scalers can also be found in schools, lecture theatres and modern churches, where numerous video sources (e.g. DVD video, live camera feeds, DVI/VGA output from a computer) need to be switched between, while the highest possible resolution is maintained.

Video scalers are primarily a digital device, however they can be combined with an analog-to-digital converter (ADC, or digitizer) and a digital-to-analog converter (DAC) to support analog inputs and outputs. One upscaling process that has gotten a lot of attention is the IMAX DMR.


Scaling a signal to match the display

This is a comparison of several common video resolutions. The more pixels in an image the greater the possibility for finer detail and fidelity.

A blow-up of a small section of a 1024x768 (VESA XGA) resolution image. The picture is actually made up from very small squares – these are pixels.

The "native resolution" of a display is how many physical pixels make up each row and column of the visible area on the display's output surface. There are many different video signals in use which are not the same resolution (neither are all of the displays), thus some form of resolution adaptation (video scaling) is required to properly frame a video signal to a display device. For example, within the United States, there are NTSC, ATSC, and VESA video standards each with several different resolution video formats.

Image artifacts/errors related to video scaling

  • Banding or posterization
  • Scaler ringing
  • Double scaling – When a source device is used which upscales to a resolution not native to a television's display, the TV can scale the image a second time which unnecessarily reduces the final output quality.

Video processor

Video scalers are often combined with other video processing devices or algorithms to create a video processor that improves the apparent definition of video signals. These other devices may include the ability for:

  • deinterlacing
  • aspect ratio control
  • digital zoom and pan
  • brightness/contrast/hue/saturation/sharpness/gamma adjustments
  • frame rate conversion and inverse-telecine
  • color point conversion (601 to 709 or 709 to 601)
  • color space conversion (Component to RGB or RGB to Component)
  • mosquito noise reduction
  • block noise reduction
  • detail enhancement
  • edge enhancement
  • motion compensation
  • primary and secondary color calibration (including hue/saturation/luminance controls independently for each)

These can either be in chip form, or as a stand alone unit to be placed between a source device (like a DVD player or set-top-box) and a display with less-capable processing. The most widely recognized video processor companies in the market as of June 2007 are:

  • Genesis Microchip (with the FLI chipset – was Genesis Microchip, STMicroelectronics completes acquisition of Genesis Microchip on 01/25/08)
  • Sigma Designs (with the VXP chipset – was Gennum, Sigma Designs purchased the Image Processing group from Gennum on February 8, 2008)
  • Integrated Device Technology (with the HQV chipset and Teranex system products – was Silicon Optix, IDT purchased SO on October 21, 2008)
  • Simplay Labs - Silicon Image (with the VRS chipset and DVDO system products - was Anchor Bay Technologies, Silicon Image purchased ABT on Feb 10, 2011)

All of these companies' chips are in devices ranging from DVD upconverting players (for Standard Definition) to HD DVD/Blu-Ray Disc players and set-top boxes, to displays like plasmas, DLP (both front and rear projection), LCD (both flat-panels and projectors), and LCOS/”SXRD”. Their chips are also becoming more available in stand alone devices (see "External links" below for links to a few of these).