Scan converters, on the other hand, do just the opposite: they convert a high resolution computer-video signal to match the low resolution needs of video, so that the computer image can be viewed on a television or recorded on a DVD recorder.

Analog television resolution was stated in ''lines of resolution,'' as we move away from analog video and toward digital video, we can now express the quality of both still images and motion video images in terms of ''pixel resolution.''

The relative number of pixels that comprise an image tells us a great deal about the image and whether it has more, or less, resolution than the television image we've set as our standard of reference. It's important to match the output of the scaler to the native resolution of the display in order to realize the highest image quality and to utilize the maximum available image area on the display.

Advantages of a Scaler

Perhaps the most important, key attribute of a video scaler is the way in which it can simplify the design of an A/V system. When video signals are scaled up to match the native resolution of the display, the system requires only one RGBHV connection to the display. This reduces installation time and cabling, and minimizes control system programming as well.

Other advantages include:

• Fewer points of failure
• Allows the use of smaller conduit
• Simplifies operation and control
• Speeds operation by eliminating the need for the projector to switch between inputs
• Image sizing and aspect ratio control
• Pre-programmed, common resolutions native to typical display devices
• Input rate auto-scanning
• Memory presets
• Remote control via IP and/or RS-232

 
Scan Converters

There are just as many occasions in which computer resolution images must be converted for use in a television or video presentation application. For example, computer graphics such as those used in PowerPoint presentations must be

converted to a video signal in order to be transmitted over a video cable, or recorded on a DVD. In cases such as these, the resolution of the image is higher than the capability of the system that will convey the image to the viewer. To make the conversion from a higher resolution image to a lower resolution, we typically use a reverse scaler, or scan converter.

The scan converter is an image scaler that's specially designed to decrease, or conform, computer-video image resolution to match that of a lower resolution system such as video, or to that of MPEG-2 data for Internet streaming applications. The scan conversion process is complicated by the fact that some information in the original image may be lost in the down-conversion process.

Most scan converters include specialized, adjustable image filters that can be used to minimize the loss of detail and provide the best possible image when the original is compressed.

Scan Converter Attributes to Consider:

• Compatibility with the computer's maximum output resolution
• Ability to genlock two or more input signals
• Quantizing level, or width of data bit path used to process image information
• Quality of the broadcast or MPEG-2 encoder
• The necessary output video formats required for use
• Support for digital input and output formats such as SDI and HD-SDI
• Need for a test pattern generator
• Ability to manage product updates via software downloads and field-upgradeable hardware

 
Categories

Video Scalers
Video Scalers are commonly used to scale standard definition video signals, such as component video, S-video, and composite video, to high resolution output rates, including HDTV. Many of the scalers in this category also offer input switching, aspect ratio conversion, and quad standard video decoding for worldwide compatibility.

RGB Scalers
RGB Scalers accept RGB/computer-video high resolution sources and scale them to another RGB/computer-video resolution — or HDTV or plasma/LCD resolution depending on the scaler. They also include additional capabilities, such as picture controls for brightness and contrast.

Video & RGB Scalers Video & RGB Scalers are capable of scaling HDTV, RGB, component video, S-video, composite video formats up or down into a single output resolution — while maintaining optimum image quality. These scalers offer multiple scaled output rates, including computer-video, plasma or LCD, and HDTV rates. Seamless Switchers Seamless Switchers provide high performance scaling of standard definition video, HDTV, and computer-video sources to high resolution output rates, including HDTV. They also offer true seamless switching between inputs with selectable transition effects for professional quality presentations.

Scan Converters
Scan Converters optimize high resolution computer-video signals for use on standard definition video displays. Each scan converter Extron manufactures provides a different set of features and level of functionality.

Scaling Matrix Switchers
Scaling matrix switchers are designed for applications requiring all video input signals to be scaled to a common video output rate.

Universal Signal Processors
A Universal Signal Processor combines high performance scaling, switching, scan conversion, standards conversion, and transcoding in one unit. It accepts a wide range of video input signals and transcodes them, or converts them up or down, into a number of different signal formats to meet the video signal requirements of virtually any system.