BioWall

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Camera
This experiment allows to display a video stream from a standard web-cam on the BioWall. Colors are mapped into eight color-levels (between green and red) to be compatible with the BioWall's LEDs.

The BioWall's cellular tissue has not been designed specifically to be used as a video display. It is however possible to display digital images and even video streams in low resolution and at low frame rates by means a rather sophisticated design.

The camera experiment allows to display a video stream coming from a standard web-cam on the BioWall. We use a Logitech camera with an image resolution of 160x120 pixels and 32 bits of color information. The captured video-stream is pre-processed on a PC before a special bit-stream is sent to the BioWall.

The pre-processing basically consists in:

Cutting and scaling the image to the BioWall's resolution (100x320 pixels). The video-stream is actually displayed twice (side by side) on the BioWall.
Converting colors to eight color-levels (between green and red) by means of the Floyd-Steinberg algorithm.

To display the video bit-stream, the BioWall's molecules are configured to form a large shift-register. The bit-stream is decoded within each molecule and the information received is displayed. The actual frame-rate is about one image per second.

In addition, a three-image animation with a much higher frame-rate can be generated on the BioWall itself: by touching one of the touch-sensitive membranes, the current image is memorized in a special memory located within each molecule. When all available memories are full, the three images are displayed in an infinite loop (at about 8 frames per second).

For further information

R. W. Floyd and L. Steinberg. "An adaptive algorithm for spatial greyscale". Proceedings of the Society of Information Display, 17(2):75-77, 1976.

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