Go to the NASA Homepage
Search >
Click to Search
Human Systems Integration Division homepageHuman Systems Integration Division homepage Organization pageOrganization page Technical Areas pageTechnical Areas page Outreach and Publications pageOutreach and Publications page Contact pageContact page
Human Systems Integration Division Homepage
Outreach & Publications Sidebar Header
Go to the Outreach & Publications pageGo to the Outreach & Publications page
Go to Awards pageGo to Awards page
Go to News pageGo to News page
Go to Factsheets pageGo to Factsheets page
Go to Multimedia pageGo to Multimedia page
Go to Human Factors 101 pageGo to Human Factors 101 page
What is Human System Integration? Website
Publication Header
Halftoning method for the generation of motion stimuli  (1989)
Abstract Header
We describe a novel technique in which color table animation in conjunction with a single base image can be used to generate a broad class of motion stimuli. We have applied this technique to the generation of drifting sine-wave gratings (and by extension, sine-wave plaids). For each drifting grating, sine and cosine spatial phase components are first reduced to 1bit/pixel by using a digital halftoning technique. The resulting pairs of 1-bit images are then loaded into pairs of bit planes of the display memory. To animate the patterns, the display hardware's color lookup table is modified on a frame-by-frame basis. Because the contrasts and temporal frequencies of the various components are mutually independent, a large number of two-dimensional stimulus motions can be produced from a single image file. We also analyze the effects on the stimulus of a variety of artifacts: the spatial artifacts produced by the halftoning process, the spurious motion signals produced by the interaction of these spatial artifacts and the temporal animation, the artifacts produced by intensity quantization (and inaccurate gamma correction), and, finally, the important but rarely considered artifact of nonlinear spatial summation. We propose a physical model to account for the observed failures of pixel independence that provides an excellent fit to our measurements.
Private Investigators Header
Authors Header
Groups Header
Keywords Header
generation, Halftoning, method, motion, stimuli
References Header
Journal of the Optical Society of America A 6: 1217-1227
Download Header
Adobe PDF Icon  josa89.pdf (Download Acrobat Reader Click to download Adobe Acrabat Reader)
  (1803KB) (application/pdf)
Go to the First Gov Homepage
Go to the NASA - National Aeronautics and Space Administration Homepage
Curator: Phil So
NASA Official: Alonso Vera
Last Updated: August 15, 2019