A videowall typically requires a significant investment, and is often the most expensive line item in a facility’s capital outlay for an AV project. While the videowall functions as a single display, it is always important to remember that it is a system.
Videowall processors are a significant component of the videowall in terms of cost. They provide features common to conventional scalers or video processors, but have greater input, output, and processing capability. The increased number of inputs and outputs creates requirements for many more dimensions of processing and image enhancements, providing greater value.
Videowalls have several distinct attributes and advantages, with image display capability and flexibility that simply cannot be achieved otherwise.
Because of the investment necessary to acquire and install a videowall, an inexperienced designer may be tempted to seek an alternative means of presenting large images or multiple sources simultaneously. Such means could include increasing picture size from a single projector, using conventional signal switching and distribution in place of a videowall processor, or installing independent LCD panels on a wall instead of an integrated videowall array. However, videowalls have several distinct attributes and advantages, with image display capability and flexibility that simply cannot be achieved otherwise.
Pixel density is the number of pixels per unit area, and is determined by the resolution and screen size of a display. When a single projected image is enlarged, pixel density decreases. However, for a videowall, pixel density is constant regardless of the array size, because it is based on the individual display unit. Enlarging the array increases the overall resolution of the videowall.
A videowall usually delivers much higher pixel density than a projected image of the same size. An image can be upscaled for enlargement on a videowall, so that it fills up the array without compromising picture quality. In contrast, significantly enlarging an image from a projector reduces apparent resolution and image quality.
Images that occupy large viewing areas need sufficient resolution or pixel density in order to present clear and legible content. Figure 1-1 . illustrates two images of equal size, one from a single 1080p projector fed by a multi-window processor, and the other a 3x3 videowall with 1080p panels via a videowall processor. Both are presenting the same content and layout for displaying multiple high definition input sources. However, the videowall can present the sources with nine times as many pixels when compared to the single projected image. This increased resolution, resulting from a higher pixel density, enables presentation of a row of three HD video sources at full resolution, compared to just 640x360 per image for the single display.
A videowall is created by “tiling” multiple display devices together. By tiling displays, videowalls of any size and aspect ratio can be constructed, often in very creative ways. A videowall display layout never has to be limited to the standard 16:9, 16:10, or 4:3 aspect ratios of single displays. Additionally, displays in a videowall can be oriented horizontally or vertically, or even a combination of both, further enhancing creative possibilities.
A front projector usually requires significant throw distance to produce an image that fills up a substantial portion of a wall. Practical throw distance requirements may limit the number of allowable participants in the room without blocking the projected image, even when special wide angle lenses are used. Videowalls comprised of flat panels or projection cubes occupy a compact footprint, due to each display’s fixed depth. This depth remains constant, regardless of how large the videowall may be. See Figure 1-2 . A display array 20 units wide and 10 units high shares the same depth of a single display device.
A bright, clear image is crucial for a video display. Whether being viewed by a workforce interpreting on-screen information, or by customers casually glancing at digital signage in a retail environment, images must be sufficiently bright so that content will be clear and easy to decipher.
A bright, clear image is crucial for a video display. Videowalls present viewers with consistently bright, inviting images, regardless of size.
Videowalls present viewers with consistently bright, inviting images, regardless of size. While a single projector loses brightness as image size increases, there is no reduction in brightness as more displays are added to a videowall. A videowall with 40 screens is just as bright as a videowall with four screens.
Most flat panels and projection cubes have internal scalers that allow a single image to be stretched across a tiled array. This may be suitable for applications that only use videowalls for displaying a single, large image. For applications requiring simultaneous presentation of multiple image sources, a simple solution is to feed sources directly to individual displays in the videowall. A switcher, distribution amplifier, or matrix switcher can be used to provide some flexibility in distributing signals to the displays.
However, with this solution, the number of sources that can be presented will frequently be limited by the number of displays in the videowall. For example, a 2x2 videowall with a matrix switcher will allow for simultaneous display of four image sources.
A videowall processor is a far more versatile and powerful solution. It provides the flexibility to present multiple sources on fewer screens by allowing a user to display multiple source windows on each display. Windows can always be sized and positioned as necessary to accommodate the number of images to be presented.
A videowall processor accepts and processes multiple signal formats such as standard definition video, computer graphics, and high definition video, so they can be simultaneously displayed together. Each source can be displayed on any part of a videowall, and many different source types can be displayed within a single screen. See Figure 1-3 . The ability to “mix and match” signal formats for simultaneous viewing can be a crucial factor for workflows that rely on a variety of visual data sources, as well as the flexibility to determine how they should be positioned or grouped together.
Figure 1-3. Sources of various formats and resolutions can be combined on a videowall. Aircraft images from Analytical Graphics, Inc. - www.stk.comThe ability to “mix and match” signal formats for simultaneous viewing can be a crucial factor for workflows that rely on a variety of visual data sources, as well as the flexibility to determine how they should be positioned or grouped together.
Videowall processors supply a consistent output signal format, eliminating the need to save unique input adjustments such as size, position, or phase for different signal types on each display. Managing multiple input formats across a common output format simplifies integration, since the displays need only be configured for one resolution and refresh rate. Driving the display at its native resolution will maintain the best quality image, avoiding inefficient or unnecessary scaling within the display.
Videowall processors typically provide better image scaling quality over the internal scaling for the displays. This can be clearly visible when magnifying images for arrays larger than 2x2, or when high resolution images are downscaled. The latter is particularly important for applications in which critical details in graphs, data screens, and camera feeds need to be discernible, despite the smaller image sizes.
A videowall processor provides full flexibility to customize presentations by adding, sizing, and placing windows, and assigning input sources to them. Any window can be as small as desired, or as large as the entire videowall. Additionally, windows can be layered over each other. Videowall processing automatically optimizes the input source to the size of the window. Many more enhancements are available, including window borders and captions, live backgrounds from a source input, and maps, logos, or other graphics stored on the processor for use as static backgrounds. Videowall processors let the user precisely define the look and style of the presentation, and also allow window layouts to be created, saved, and then recalled.
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