Friday, January 16, 2009

Solving the Aspect Ratio Issues

We ran into some challenges in trying to connect the computers, projectors and wide screen interactive white boards. It is not nearly as easy to make these work together in an easy way. The real difficulty comes form the differing aspect ratios of the equipment. The Promethean boards are in a “High Definition” 16:10 aspect ratio. Just like most movie screens, the display here is a rectangle that is wider horizontally than it is high. Most of our computers are not native in the “high definition” 16:10 aspect ratio, instead they have the old school square 4:3 aspect ratios that all older televisions have.

The projector has even more variables to it. You can buy projectors in either format with the 16:10 format called wxga or the 4:3 format called svga. There are even projectors that will take a svga signal (4:3) and then display a 16:9 image. In order to do this conversion, the projector must insert additional pixels into the horizontal image, and this can cause problems when used with a Interactive Whiteboard. The whiteboard needs to track the movement of the pen over the entire surface and if it encounters a band of these inserted pixels, then it can cause frustrating dead spots in the board. The computer and the interactive white board need to talk to each other and match each part of the projected screen to a pixel on the computers actual screen.

While you can use the display control panel on the computer to vary the image on the computer screen, and it is possible to get the computer to output a 16:10 format, it has to be the primary monitor for the computer and reset each time the computer is attached to the classroom system. This is just a pain, and more work than most teachers want to do. They just want to hook up and go.

After hours of research and testing various combinations of projectors, computers and our 95 inch interactive white board, we have decided to use the Epson svga projector and have it do the conversion to the 16:9 image. This will give us the ease of use that we feel is so critical to our program. Teachers will just be able to take their native svga computers and connect it to the system and have it work. They will not have to do any image conversion on the projector or the laptop. Finally, our testing did not reveal any noticeable dead spots in the board.

No comments: