Faroudja Video Processing and Genesis Controller Chips
Introduction
Advanced Colour Management (ACM)
Directional Correlational
Deinterlacing (DCDi)
Film Mode Detection Technology
/ Bad Edit Detection
Motion Adaptive Noise Reduction
Problems Caused by Faroudja Processing
Faroudja Video Processing and Genesis Controller Chips
Many monitors use controller microchips manufactured by Genesis. They produce HD capable Digital TV controllers for use in LCD TV's (Genesis Microchip PurView HD) which offer video enhancements from Genesis as well as Faroudja, one of their subsidiaries (see below). Genesis were the first company to offer single-chip scaling solutions to meet growing requirements for resolution scaling on screens with a fixed native resolution. This was particularly important with the massive growth of LCD displays and televisions in recent times. Genesis also introduce Response Time Compensation (RTC) into their controller chips to help reduce motion blur and ghosting which can be a problem on liquid crystal displays.
Faroudja is a subsidiary of Genesis, and have developed a suite of video enhancement technologies designed to help improve image quality, without introducing artefacts. Faroudja helped develop up-conversion equipment to allow broadcasters to continue to transmit legacy NTSC (US TV standard) from existing equipment during the transition to HDTV. One of the main problems was that traditional upscalers resulted in jaggedness to diagonal edges in video and so Faroudja developed DCDi to help eliminate this problem (see below). They combined this with several other enhancements to form the Faroudja Video Processing Technology. The following enhancement algorithms form the Faroudja suite:
One of the key aspects of the Genesis Controller chips is the Advanced Colour Management (ACM) which was designed to compensate for the reduced brightness and contrast in LCD displays relative to traditional CRT screens. Video can often look dim and less colourful when viewed on an LCD display and ACM was designed to help overcome this. The Genesis ACM suite of Algorithms includes:
Adaptive Colour and Contrast (ACC)
Active Colour Management (ACM-II)
Active Colour Management 3D (ACM-3D)
These are designed to
enhance colours and adaptively augment contrast levels on LCD displays. A series
of viewing presets are supplied with modes like 'sport', 'video' and 'nature'
being available for example. These offer various preset configurations of the
ACM algorithms designed to help bring the best out of the screen in various
situations. Use of these algorithms and enhancements varies from one Genesis
chip to another.
Further Reading: ACC / ACM White Paper
Directional Correlational Deinterlacing (DCDi)
Faroudja's unique DCDi
algorithm identifies all the moving edges in a scene and adjusts the angle of
interpolation at each pixel so that the interpolation always follows the edge
instead of crossing it, eliminating staircasing or jagged edge artefacts. This
technology, in combination with its decoding, deinterlacing and enhancement
technologies, won an Emmy Award from National Academy of Television Arts and
Sciences in 2001. The DCDi algorithm is now incorporated into Genesis
Microchip‘s video controllers that were derived from the Faroudja technology.
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Film Mode Detection Technology / Bad Edit Detection
In 1989 Faroudja developed a technology which detected film content which has gone through "3:2 pull-down" for conversion to NTSC (this was a process for delivering content in US NTSC format). This technology from Faroudja detects any content which has been subject to this 3:2 pull-down and by blending the fields back together, the original film frame-rates are recreated. Thanks to Faroudja's "Bad Edit Detection" the image produced is free of motion artefacts and has full vertical resolution. This processing is particularly important and beneficial when switching between commercials (normal mode) and a movie (film mode) and this technology is widely accepted in the industry.
Video enhancements can often lead to artefacts in use due to the "peaking filters" which are commonly used to enhance high frequency components of the video signal. Genesis do not use a peaking filter but instead use their TrueLife Enhancement technology to identify transitions considered to be the details in an image such as skin texture, freckles or hair. These detail transitions are deliberately enhanced making them more visible and more lifelike. The technology also enhances large edges to create greater depth of perception without introducing visual artefacts or distortion.
Motion Adaptive Noise Reduction
Filtering can help eliminate noise in image playback, and this can be done spatially (2-D) or temporally (3-D). Spatial filtering results in a soft image with loss of detail. Temporal filtering does not create loss of detail, but if done incorrectly, does result in smearing or ghosting of moving objects in the image. Genesis uses Motion Adaptive processing to reduce noise without introducing smearing.
When composite video is not decoded perfectly, it can lead to an artefact referred to as cross colour. This is effectively the presence of colourisation where there shouldn't be any. This is particularly noticeable in very hectic scenes and the most common and visible cross colour artefacts are flickering that occurs at 15 Hz rate, flashing colours or rainbow patterns. Faroudja's Cross Colour Suppression uses various filters to help eliminate this problem depending on whether the motion detector technology identifies motion in the image.
This is self-explanatory really. This handles video of different aspect ratios, whether it be 4:3, 16:9, 16:10 etc. Faroudja's Aspect Ratio Technology handles video of various formats and successfully adapts these to the screen being used.
Problems Caused by Faroudja Processing
Recent TFT releases have brought up a lot of discussion about the Faroudja processing technology. Most notably the new Dell 2007WFP and Dell 2407WFP which showed some quite noticeable banding in colour gradients. Dell acknowledged the problem and addressed this with the following statement:
“Dell has a firmware update that adjusts the ACC (Adaptive Color and Contrast) & ACM (Active Color Management) features, eliminating the banding issue when using the Desktop mode. All of these monitors have three display modes: Desktop, Multimedia and Gaming. The firmware turns off Faroudja video processing in Desktop mode. It remains enabled in the other two modes.”
It seems that the presence of the Faroudja video processing in these models (which feature a Genesis chip) has lead to some issues. Potentially the presence of ACC and ACM in certain circumstances can lead to problems, and I would suggest this is only where other components are used in conjunction with the chip. Dell disabled these features in the “desktop” preset mode, but left it on in the other settings. The impact of this is obvious, with users reporting the presence of banding in the other modes, but not in “desktop” use.
DCDi Information
ACC / ACM White Paper
Example Genesis Controller Chips:
FLI5962H - As used in the Dell 2407WFP
GM1601 - As used in the Dell 2405FPW
