Strobing to Mitigate Vibration for Display Legibility

The innovation improves upon the performance of passive automatic enhancement of digital images. Specifically, the image enhancement process is improved in terms of resulting contrast, lightness, and sharpness over the prior art of automatic processing methods. The innovation brings the technique of active measurement and control to bear upon the basic problem of enhancing the digital image by defining absolute measures of visual contrast, lightness, and sharpness. This is accomplished by automatically applying the type and degree of enhancement needed based on automated image analysis. The foundation of the processing scheme is the flow of digital images through a feedback loop whose stages include visual measurement computation and servo-controlled enhancement effect. The cycle is repeated until the servo achieves acceptable scores for the visual measures or reaches a decision that it has enhanced as much as is possible or advantageous. The servo-control will bypass images that it determines need no enhancement. The system determines experimentally how much absolute degrees of sharpening can be applied before encountering detrimental sharpening artifacts. The latter decisions are stop decisions that are controlled by further contrast or light enhancement, producing unacceptable levels of saturation, signal clipping, and sharpness. The invention was developed to provide completely new capabilities for exceeding pilot visual performance by clarifying turbid, low-light level, and extremely hazy images automatically for pilot view on heads-up or heads-down display during critical flight maneuvers.

The Spatial Standard Observer (SSO) provides a tool that allows measurement of the visibility of an element, or visual discriminability of two elements. The device may be used whenever it is necessary to measure or specify visibility or visual intensity. The SSO is based on a model of human vision, and has been calibrated by an extensive set of human test data. The SSO operates on a digital image or a pair of digital images. It computes a numerical measure of the perceptual strength of the single image, or of the visible difference between the two images. The visibility measurements are provided in units of Just Noticeable Differences (JND), a standard measure of perceptual intensity. A target that is just visible has a measure of 1 JND. The SSO will be useful in a wide variety of applications, most notably in the inspection of displays during the manufacturing process. It is also useful in for evaluating vision from unpiloted aerial vehicles (UAV) predicting visibility of UAVs from other aircraft, from the control tower of aircraft on runways, measuring visibility of damage to aircraft and to the shuttle orbiter, evaluation of legibility of text, icons or symbols in a graphical user interface, specification of camera and display resolution, inspection of displays during the manufacturing process, estimation of the quality of compressed digital video, and predicting outcomes of corrective laser eye surgery.

A laser or a light source is incident on a detector. It usually passes through a shutter that can open and then close to limit the amount of light hitting the detector. There are limitations on the speed, size and cost of such apertures. The design of this technology uses DLP mirror technology. It can rapidly deflect the incoming light beam onto an aperture, which blocks the beam path, or through the aperture, which allows it to go onto the detector. The DLP mirror in this shutter uses an aperture design that is nearly 3 orders of magnitudes faster (shorter exposure time) than similar-sized aperture using conventional commercial-off-the-shelf mechanical shutters and 1-2 orders of magnitude smaller and cheaper than higher-performing custom-made shutters that are used by a few labs around the world. The DLP mirror is actuated via a computer controlled oscillator circuit. A laser beam directed to the mirror is either passed to a target detector, or diverted, based on the inputs from the circuit. In this manner, the DLP mirror / circuit can act as a fast shutter, modulator, or chopper for the light beam. One novel feature of this invention is the application of the DLP to divert a beam onto or off a detector for instrumentation systems.

A supersonic shock wave forms a cone of pressurized air molecules that propagates outward in all directions and extends to the ground. Factors that influence sonic booms include aircraft weight, size, and shape, in addition to its altitude, speed, acceleration and flight path, and weather or atmospheric conditions. NASA's Real-Time Sonic Boom Display takes all these factors into account and enables pilots to control and mitigate sonic boom impacts. How It Works Armstrong's technology incorporates 3-dimensional (3D) Earth modeling and inputs of 3D atmospheric data. Central to the innovation is a processor that calculates significant information related to the potential for sonic booms based on an aircraft's specific operation. The processor calculates the sonic boom near a field source based on aircraft flight parameters, then ray traces the sonic boom to a ground location taking into account the near field source, environmental condition data, terrain data, and aircraft information. The processor signature ages the ray trace information to obtain a ground boom footprint and also calculates the ray trace information to obtain Mach cutoff condition altitudes and airspeeds. Prediction data are integrated with a real-time, local-area moving-map display that is capable of displaying the aircraft's currently generated sonic boom footprint at all times. A pilot can choose from a menu of pre-programmed maneuvers such as accelerations, turns, or pushovers and the predicted sonic boom footprint for that maneuver appears on the map display. This allows pilots to select or modify a flight path or parameters to either avoid generating a sonic boom or to place the sonic boom in a specific location. The system also provides pilots with guidance on how to execute a chosen maneuver. Why It Is Better No other system exists to manage sonic booms in-flight. NASA's approach is unique in its ability to display in real time the location and intensity of shock waves caused by supersonic aircraft. The system allows pilots to make in-flight adjustments to control the intensity and location of sonic booms via an interactive display that can be integrated into cockpits or flight control rooms. The technology has been in use in Armstrong control rooms and simulators since 2000 and has aided several sonic boom research projects. Aerospace companies have the technological capability to build faster aircraft for overland travel; however, the industry has not yet developed a system to support flight planning and management of sonic booms. The Real-Time Sonic Boom Display fills this need. The capabilities of this cutting-edge technology will help pave the way toward overland supersonic flight, as it is the key to ensuring that speed increases can be accomplished without disturbing population centers.

Supersonic flight over land is generally prohibited because sonic booms created by shockwaves disturb people on the ground and can damage property. Armstrong innovators are working to solve this problem through a variety of innovative techniques that measure, characterize, and mitigate sonic booms. The BOSCO technology is helping researchers understand how sonic booms travel through the air. How It Works Armstrong's patented system visualizes air density gradients generated by air compressing as it flows around an object. Researchers first obtain a celestial background image and then collect a series of images of an object in supersonic flow in front of the celestial object. The density change in the air refracts the light, shifting the background as compared to the undisturbed background image. The amount of movement corresponds directly to density gradients in the airflow. Using computer algorithms to analyze the images, resultant images essentially show the distortions caused by the aerodynamic flow of shockwaves passing between the camera and the celestial background. Why It Is Better Schlieren photography has been used for years in wind tunnels, where the environment is controlled. BOSCO enables its use in the real atmosphere with real propulsion systems. Studying life-sized aircraft flying through Earth's atmosphere provides better results than modeling and can help engineers design better and quieter supersonic airplanes. In addition to studying shock waves for aircraft, NASA's schlieren techniques have the potential to aid the understanding of a variety of flow phenomena and air density changes, such as investigating air flows around tall buildings and the tips of wind turbines and helicopter blades.