Finally, we computed the overall luminance of each filmby finding themedian luminance value of each frame, then averaging across frames. For the black-and-white films we simply worked with 8-bit pixel values of 0 (black) to 255 (white) fromthe jpegs; for the color films we first converted them to grayscale using the standardMatlab conversion, and then measured them in the same way. Median values for each frame were then given a reverse gamma transformof 1/ before the whole-filmmean luminance was calculated
