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5/3/07 New Chassis for Serial Button Box! See below...
The Automatic Text Insertion Machine
This interface was designed for a researcher who studies peoples' facial expressions. She wanted to display a series of images on a computer screen and record the reactions of her test subjects for later analysis.
More specificially, she needed to know which of several hundred images her subjects were viewing at any given time, as well as the time each image was displayed. Also, the interface had to be compatible with Empirisoft's Medialab software.
We designed a simple, intuitive system with two inputs and one output. A parallel port connects the Text Insertion Machine with the host computer. A video input port allows a video camera to be connected. The interface then overlays the desired user data with the video signal and sends it to a video output port, which can be connected to a VCR, DVD recorder or television monitor.
The overlaid data looks similar to a 'closed caption' display on a television set. There are two lines of data dispayed: the first consists of 34 characters which are user definable and adjustable in realtime. The second line contains a counter which increments when a new experiment begins, a stopwatch display with 1/30 second resolution (the maximum available in a video-based system), and the number of each displayed image. Below is a screen shot:
Of course, by switching into 'Text Edit Mode,' the first line of characters can be edited. The beauty of the interface is that this text can be updated or cleared on a moment's notice via 2 knobs on the front panel. One adjusts the cursor position, the second scrolls through alphanumeric characters. It's fast. It's easy. It's really cool. Note that in these examples, all text is displayed with a 'halftone' background. This means that the original video image is visible behind and through the words.
Alternately, the text can have a completely black background, or no background at all. In our opinion, the halftone background is the nicest.
The subject counter can be incremented or resetted manually (in this case, to 8).
When the box is placed in 'run' mode, it takes all control cues from the host computer. When MediaLab sends out the 'experiment begin' signal, the experiment counter increments. As each successive random image is displayed, the image's title is displayed on screen and the stopwatch begins to count.
If you don't need to interface with a specific software program but want a fast and elegant real-time character generator, the Automatic Text Insertion Machine can be modified to match your application.