Figure 3.

Demonstration of how spatial fractal D is calculated using stimulus condition gray scale spatial slope of 2.25 and temporal slope of 2.25. (A) Before box counting, the frames of each movie stimulus were thresholded (i.e., binarized). This consisted of converting all pixels above mean luminance to white (255) and all pixels below to black (0). B) The box-counting procedure consisted of overlaying each frame with a mesh grid of equally sized boxes. Boxes which contained pixel values 0 and 1 were counted as occupied. This procedure was conducted across multiple spatial scales, and the maximum number of scales analyzed was equal to maximum number of times the image size could be divided by 2, with the smallest box size being 2. For stimuli in the present study, seven scales were counted (256 -> 128, 64, 32, 16, 8, 4, 2). Only four scales are depicted for brevity. (C) After box counting, spatial fractal D is calculated by fitting the slope of the relationship between box size and box occupancy a log–log axis. This value was calculated for each frame separately. The final spatial reported value is the average across all frames.