If advanced scaling algorithms, improved image equalization, and custom zooming (aspect ratios) will assist in providing a better image suited to your requirements, or you’re experiencing EDID/handshaking issues, an outboard video processor may just be the solution for you. If you’re an industry veteran, you probably recognize the term “video processor,” or “video scaler” from the days when Faroudja introduced the line doubler to convert standard definition video from 480i to 480p, a process that effectively “doubled” the lines of resolution on a display at a given time. Since then, video processors have had a significant impact on our television system, evolving into scalers and video equalizers. Today, nearly every display on the market has a video processor built in to accommodate the copious amounts of video formats available. As built-in processors have improved, my company is often asked the question, “Do I really need a video processor?” The answer, as you may expect, is quite complicated.
Originally, video processors were developed to improve lower resolution sources, starting with de-interlacing, then scaling images to different resolutions, and eventually adding advanced equalization capabilities. During this time, advancements made the technology more cost effective, allowing manufacturers to include video processing as a built-in feature, even if it was limited, compared with its “outboard” counterparts.
Today, almost all display devices come with a built-in video processor that is quite capable. At the same time, outboard video processors are as affordable as ever–the majority ranging from about $500-$5,000. I know what you’re thinking. If displays come with a quality built-in processor, why would I need to go with an outboard one? Generally speaking, it comes down to the requirements of the application and the display system with which it will be used.
Lumagen’s latest video processor models are the Radiance 2021, 2041, 2022, and 2042. The 2021 and 2041 feature only HDMI inputs, while the 2022 and 2042 offer analog video inputs as well. Today’s built-in video processors will, for the most part, utilize advanced scaling algorithms allowing for resolution and frame-rate conversion to be accomplished without a glaring issue. Additionally, they will often implement basic equalization features for calibration, such as two-or 10-point grayscale/gamma tracking and single-point color decoding/color management adjustments. To clarify, the “single point” involves adjusting red, green, blue, cyan, yellow, and magenta at one spot instead of having multiple points for each color. Sizing is often limited to either one-to-one pixel mapping or an approximate two-percent overscan. Because of this, the only way to make an image perfectly fit the screen is often to provide an image at the native resolution of the display. This is important when using a computer, because the interface is not cropped. The color space and resolution requested over the EDID is left up to what the manufacturer built into the display; we have found at times that this is not ideal, as what is requested may not be what is optimum, which leads to a sub-par image.
Outboard video processors, on the other hand, often have a significant amount of capability above and beyond today’s built-in units. Their scaling algorithms are often more advanced, allowing for bad edit detection to clean up improperly formatted source content and proper filtering of chroma upsampling errors when applicable. Their equalization adjustments for calibration are often more sophisticated with not only multipoint grayscale/gamma and color management adjustments, but also the introduction of 3D LUTs (look-up tables) for improved grayscale/gamma and color gamut mapping capability. LUTs offer a significant number of adjustment points over traditional color management systems and can greatly improve color accuracy on today’s consumer displays. Input and output sizing allow for custom aspect ratios and overscan on a per-requirement basis. As an example, if an anamorphic lens is used to allow a 1.78 imager to be filled with 2.39 formatted content, the outboard scalar could provide the vertical stretch necessary to do so. Additional sizing options such as a zoom for standard definition 1.33 letterboxed content to 1.78 are now easily achieved; of course, this will not be as sharp as higher resolution content, but clients often love filling their screen area.
One side effect of using an outboard video processor has been the ability to correct HDMI handshake issues between products. Most outboard processors allow for the user to force the desired input and output signal to optimize for color space, as well as correct for poor EDID. In some cases, we have found that a quality video processor can allow for a handshake between two components that otherwise would not talk to each other.
So, should you purchase an outboard video processor for the systems that you install? If advanced scaling algorithms, improved image equalization, and custom zooming (aspect ratios) will assist in providing a better image suited to your requirements, or you’re experiencing EDID/handshaking issues, it may just be the solution for you.
David Abrams is president of Avical, a Los Angeles-based audio/video calibration and consulting company. Follow him on twitter @AvicalTweets or on Facebook at www.facebook.com/Avical.Inc