One problem faced by many churches using video projection systems is the inability to do a smooth transition between an image from a computer system to an image sent from a videocassette recorder or live camera feed. Depending on the age or generation of your projector, this transition may be so involved that it could require executing several on-screen menu commands and result in the projector displaying on-screen flickers, flashes, or rolling bars until the image has re-synced. This is distracting to the viewer, and is certainly not considered technical excellence.

There is a solution to this problem, but first some things to think about and then some technical basics. Video presentation or image magnification has an inherent problem in the fact that most people see it as television, and everyone is an expert when it comes to knowing what is good television. They see it everyday in their homes and they know what to expect. Due to the fact that human’s visual senses are highly developed, any error or “glitch” is noticed by the viewer.

Sound has the same effect, as it can be a distraction. However, the church grew up with the development of sound and sound errors are more readily accepted. Video for the most part developed outside the church to a high level of technical excellence. Video errors seen on a bigger-than-life screen are not as readily accepted and can be a major distraction. Therefore, every effort should be made to attain the same level of technical excellence with video as the viewer sees at home.

Now on to some technical basics. All video projectors today have what is called a “native resolution” which is the optimized design image quality for the specific projector in use. This native resolution is stated as a pixel number such as 1024 x 768 (XGA), or 1280 x 1024 (SXGA). These are the resolutions found in many mid-range projectors in use today. For simplicity’s sake, pixels are the little “dots” that make up the image projected to the screen, and the bigger the number the better the image quality.

Pixels became the standard measurement for video projector image resolution because computers send their image data to their monitor screens in this format. Video projectors picked up this format as a measurement of resolution because the majority of them project images that originate on a computer. To get the best image from the projector, the input signal to the projector (usually from a computer) must match the native resolution of the projector. In other words, if you have a projector that has a 1024 x 768 (XGA) native resolution, the computer it is hooked up to should have it’s video output set at 1024 x 768 (XGA) resolution. This way the input to the projector matches the projectors output pixels “dot for dot.”

Simply stated, video from a computer, and video from a television source, such at a VCR or camera are not the same. However, to the audience, the end result is the same: a projected video image. The way the image gets each of those differences which affects resolution. Video from a television source exists at much lower resolution than the computer resolution discussed above, and this creates a problem for the video projector. Television resolution is not even measured in pixels; it is measured in “lines of resolution.” The important fact here is that television resolution is lower, meaning the pixel number would be lower, if that measurement was used. The result is poorer image quality. So in order to have the optimum projected image, the television signal resolution must be brought up to the projector’s native resolution.

Many projectors have a device built in which converts the television signal. However, this may require a series of menu options (often displayed) from the projector’s remote control, and the installation of a second signal cable to each of the video sources. Other projectors will “sense” the change in the signal from the active input signal and do the conversion automatically. This will often times cause a flicker, flash, or rolling image on the screen as the projector re-syncs with the new signal. Both of these are distracting and certainly would not be considered technical excellence, as it is not as smooth and seamless as television.

Now, the solutions… First and most important, have a single source signal for the projector — one cable running to the projector’s input. This eliminates the need to change the input source signal via the remote control and thus the on screen menus. Which input cable to use is not in the scope of this article, however for the best results the RGB+HV should be considered. Next, add a switcher/scaler between your input devices (computer, VCR etc) and your projector. This device will convert all your input signals to match the native resolution of your projector and provide seamless switching (no on-screen flicker, flash, or image-roll) between your input signals.

What is a switcher/scaler? The switcher is simply the device that allows the used to select the input signal that will be sent to the scaler, whether it is the computer, VCR, live camera, or television network feed. This differs from a “standard” video switcher in that the output goes to the scaler, not directly to the projector. Most of the time this switcher is integrated into the scaler, however high-end units such as the one recently installed a First Baptist Church in Midland, Texas, has a separate switcher console. More on First Baptist’s installation later.

The scaler–the heart of the system– takes the input signals and converts them to the native resolution of your projector. You will have to tell the scaler what the native resolution of your projector is, but once done, all input signals will be optimally converted.

The scaling process involves taking the low-resolution television signal and converting it to the high resolution needed for the projector. This is called up-scaling and produces the optimum picture quality of the television signal for the video projection system. Some switcher/scalers provide audio switching that follows the video input switching. Some provide digital transitions when switching, such as wipes or dissolves. Others include a front panel input for a second computer; nice for attaching a laptop used by a visiting presenter. Line doubling is another common feature found in most scalers.

We must also mention down-scalers. The down-scaler converts the high-resolution video image, produced by the computer, to the low-resolution image needed for television. These devices should not be used for video projection, as they have the inverse effect on image quality. They could appropriately be used for video stage monitors or hallway monitor systems.

The pictures provided for this article were compliments of Jim Cawthon, Media Minister, at First Baptist Church in Midland, Texas. Jim recently installed a “top-of-the-line” video presentation system that included the high-end Folsom ScreenPro Plus High-Resolution Seamless Switcher (scaler). This switcher/scaler also includes a router, which allows any input to go to, or be routed to, any projector. In the case of First Baptist’s installation, the routing is to one of two projectors, with the expansion capabilities of adding a third projector when needed. The switcher is a standalone console that is very similar to a video production console. The operator can select any input — he is currently using five (two computers, two video tape sources, and one live TV) — and send that input to either or both projectors.

While, this system is an example of the “top-of-the-line” in the switcher/scaler world, many smaller, less complex systems are available from Folsom, Extron, and Analog Way and others.

A switcher/scaler may not be for every church with a video projector, but for those that want to take their video presentations to the next level of technical excellence, this must be an option to seriously consider.

Don Brooks is the former director of technical ministries at Central Community Church in Wichita, Kansas. He now operates a no-fee consulting service called TechMissionS. It is his goal to help churches with technology in much the same way Paul helped the first church with issues of theology. He can be reached through his web site “www.techmissions.com.”