
[ description of experiment deleted ]


[ more deleted ]


A few years ago a friend and I took some 256 grey-level photos from
a 1 bit Mac Plus screen using this method. Displaying all 256 levels
synchronized to the 60Hz display took about 10 seconds. After
experimenting with different aperture settings and screen
brightnesses we found a range that worked well, giving respectable
contrast. The quality of the images was pretty good. There were no
visible contrast bands.

To minimize the exposure time the display program built 255
different 1 bit frames. The first contained a dot only for pixels
that had value 255, the second only for pixels that had value 254,
etc. These frames were stored using a sparse data structure that was
very fast to 'or' onto the screen in sequence. Creating these
frames sometimes took 5-10 minutes on that old Mac, but the camera
shutter was closed during that time anyway. And yes, we wrote
directly to the screen memory. Mea culpa.

Our biggest problem was that small images were displayed in the
top left corner of the screen instead of the center. It took
an extra week to have the film developed and printed, because the
processors took the trouble to manually move the all images into
the center of the print. Who'd have guessed?