Patent Description:
The human eye is capable of adapting to displayed information with precision over a range of <NUM> orders of magnitude in luminance, from bright day to starlight. Typically, visual displays (hereinafter, "screens") used in theaters, simulation and training, or the like offer a range less than <NUM> orders of magnitude, and their peak luminance is a tiny fraction of that of the real-world scenes being displayed or simulated.

Typically, for existing screens visual details intended to represent part of a daytime visual scene are actually rendered at luminance levels only encountered at night in the real world. The eye responds very differently at different luminance levels. In simulation and training scenarios, training fidelity may suffer when screen luminance is inappropriate for the training scenario. This lack of fidelity to real-world conditions limits the transference of training that can be achieved in a simulator and, therefore, the number of training tasks that can be performed in-simulator.

HDR has come into wide use for home entertainment and theatrical content generation. Demanding standards have been developed for capture, distribution and display of imagery that spans nearly the entire range of human visual sensitivity. Digital encoding and decoding of such HDR imagery typically requires from <NUM> to <NUM> bits, or two to four more bits than the <NUM> bits which were standard for video and computer graphics for many years. The home TV industry has been very successful adding this additional precision while maintaining affordability by adopting new technologies such as quantum dots, organic light emitting diodes and spatially modulated back lighting which can be easily adapted to the small format sizes common in consumer television. HDR TVs are now available in sizes up to <NUM> inches (diagonal, equivalent to <NUM>). Digital cinema on the other hand has struggled to come up with an affordable method to display HDR on large screens because of the high brightness and high contrast involved. Digital Cinema projectors with laser light sources and dual modulation have been developed but have not been well accepted because of cost. There are currently no displays in between these extremes that the simulation and training industry could adopt where large screen display is required.

Other drawbacks, inconveniences, and issues for current systems and methods also exist.

<CIT> in accordance with its abstract states projection displays include a highlight projector and a main projector. Highlights projected by the highlight projector boost luminance in highlight areas of a base image projected by the main projector. Various highlight projectors including steerable beams, holographic projectors and spatial light modulators are described. <CIT> in accordance with its title states a projector device, image display system, and image display method.

Accordingly, disclosed examples address these and other drawbacks, inconveniences, and issues of existing systems and methods. For instance, disclosed examples bridge the gap between existing market segments with an active screen approach that is scalable down to the high end of direct view TVs and up to moderate size theatrical venues at a cost advantage to the large and expensive, laser cannon-like HDR digital cinema projectors.

An embodiment of a method of the disclosure is set out in claim <NUM>.

An embodiment of a system of the disclosure is set out in claim <NUM>.

While the disclosure is susceptible to various modifications and alternative forms, specific examples have been shown by way of example in the drawings and will be described in detail herein.

<FIG> is a schematic flow diagram illustrating methods <NUM> of displaying HDR imagery on a screen in accordance with disclosed examples. As indicated, method <NUM> may begin at step <NUM> by inputting an HDR signal into a processing device. Any suitable image processing device may be used to decode an HDR signal of at least <NUM> bits/color/pixel such as HDR10 (<NUM> bits), Dolby Vision (up to <NUM> bits) or other appropriate HDR standards to a native RGB <NUM>:<NUM>:<NUM> video signal. Other processing devices are also possible.

At step <NUM> the processing device processes the HDR signal. Processing step <NUM> includes application of a specialized local dimming that performs amplitude and frequency separation and scaling to convert the processed HDR signal into a binary weighted digital byte that separates the HDR signal into a separate LSB component of high spatial frequency/low brightness, as shown at step <NUM>, and a separate MSB component of low spatial frequency/high brightness, as shown at step <NUM>. Processing step <NUM> includes an anti-aliasing algorithm to smooth out transitions in the high brightness MSB signal. This is accomplished by a low pass spatial filter which samples and filters the signal to remove high frequencies from the MSB portion of the signal. These high frequency components are then processed separately to appropriate amplitude and frequency scale and are added to the LSB signal. This assures that the high frequency, high amplitude components of the signal are not lost and do not produce aliasing but are reproduced in the LSB signal which is output from the step <NUM> processor. Step <NUM> also performs brightness uniformity correction to smooth out the variations in brightness produced by the high brightness zonal illuminators <NUM>. The brightness uniformity correction is added to the LSB signal output from step <NUM> processor.

As indicated at steps <NUM> and <NUM>, the separated LSB component and MSB component are then optically combined by projecting the LSB component onto the front side of a screen and the MSB component onto the back side of the same screen. In examples where the LSB component is <NUM> bits, a typical <NUM> bit per color SDR projector (or projectors) may be used to modulate the least-significant-byte of the HDR signal onto the front of the screen at high spatial resolution as indicated at step <NUM> and the MSB component may be projected onto the back of the screen as indicated at step <NUM> using, for example, a high brightness array of LED zonal illuminators, or the like, which modulate the MSB component (high brightness) end of the HDR signal at much lower spatial resolution.

<FIG> is a perspective view schematic diagram of systems <NUM> for displaying HDR imagery on a screen <NUM> in accordance with disclosed examples. As indicated, screen <NUM> has a front side <NUM> and a back side <NUM>. While shown as generally rectangular in <FIG>, screen <NUM> need not be and may be any suitable size, shape, or transparency. For example, screen <NUM> may be flat, concave, or convex, may be a dome-type screen as used in a flight simulator, or may be any other appropriate screen depending upon, among other things, the intended use and environment. Additionally, screen <NUM> is not restricted in size or shape by the availability of AMLCD panels, or the like, and can be used to create HDR displays of any size or shape including trapezoidal, toroidal or spherical.

As shown, system <NUM> includes one or more projectors <NUM>. In examples where the LSB component is <NUM> bits, a typical <NUM> bit per color SDR projector <NUM> (or projectors <NUM>) may be used to modulate the least-significant-byte of the HDR signal onto the front side <NUM> of the screen <NUM> at high spatial resolution. Other projectors <NUM> may also be used, which are preferably LCOS-type projectors with high contrast and low darkfield brightness characteristics.

System <NUM> also includes a high intensity, high brightness, light source <NUM> which may be a number of LED zonal illuminators (e.g., 210A-210N) or the like. Any number (N) of light sources <NUM> may be used. Light sources <NUM> may also be laser sources, laser diodes, LEDs, or the like. As disclosed herein, light source <NUM> is used to illuminate the back side <NUM> of screen <NUM> with the MSB component of the HDR signal.

System <NUM> also includes one or more image processing devices (e.g., processor <NUM>) in communication with projector <NUM> and light sources <NUM> and to a apply the local dimming algorithm disclosed above (step <NUM>) that performs bit separation and scaling to convert the processed HDR signal into a binary weighted digital byte that separates the HDR signal into a separate LSB component of high spatial frequency/low brightness and a separate MSB component of low spatial frequency/high brightness. Processor <NUM> may be a stand-alone device, may be integrated into the projector <NUM> or light sources <NUM>, or may be a networked or otherwise distributed device as would be apparent to those of ordinary skill in the art having the benefit of this disclosure.

System <NUM> is scalable in resolution and brightness by selecting the power and density of the light sources <NUM> (e.g., LED zonal illuminators 210A-210N) and the resolution and brightness of the projector <NUM>. Further, it is relatively inexpensive to mass produce system <NUM> in large sizes because of its use of increasingly common LED zonal illuminators (e.g., 210A-210N), low cost plastic Fresnel lenses, which may be part of the zonal illuminators <NUM>) and commodity video projectors <NUM>. As a result of this unique architecture the display system <NUM> can be scaled to a wide range of applications. It can be made larger than the typical active matrix LCD and OLED devices used for consumer television and does not require the expensive and potentially dangerous laser light sources used in HDR digital cinema projectors.

System <NUM> can also be adapted to existing flight simulator dome displays which commonly have projectors projecting onto a spherical front projection screen from inside the dome. By replacing the front projection dome with an active screen modulated on the back side with a spherical LED array these systems can be upgraded to high dynamic range. Applied to a curved screen a very high brightness, high dynamic range full field of view dome display for a flight simulator/aircrew trainer can be created.

<FIG> are schematic diagrams representing LSB components <NUM> and MSB components <NUM> in accordance with disclosed examples. <FIG> fall within the scope of the claims while <FIG> does not fall within the scope of the claims. As disclosed herein, a digital HDR video signal <NUM> (shown schematically as <NUM> bits in <FIG>) is separated into an MSB component <NUM> and an LSB component <NUM>. As shown, LSB component <NUM> may be <NUM> bits and MSB component <NUM> may be <NUM> bits (<FIG>, within the scope of the claims), <NUM> bits (<FIG>, within the scope of the claims), or <NUM> bits (<FIG>, outside the scope of the claims). For HDR signals <NUM> of sizes other than <NUM> bits other sizes for MSB component <NUM> and LSB component <NUM> may be used and may be generalized to an integer "N bit" size. Likewise, the low spatial frequency of the MSB component <NUM> may be a multiple of the high spatial frequency LSB component <NUM> selected from the series of <NUM>, ½, ¼,. , <NUM>/n, where n = even integers.

<FIG> is an illustration of another exemplary system and method for displaying HDR imagery on a screen. The system <NUM> includes an interface for receiving an input HDR signal <NUM>, such as a <NUM>-bit or <NUM>-bit video signal. The image processor <NUM>, at step <NUM>, is configured to process the input HDR signal, by removing the most significant <NUM> bits of a <NUM> bit HDR signal for example, to yield a separate <NUM>-bit LSB component of high spatial frequency/low brightness from the input HDR signal (step <NUM> may be similar to <NUM> in <FIG>). At step <NUM>, the image processor <NUM> is configured to process the input HDR signal, by removing the least significant <NUM> bits of the <NUM> bit HDR signal for example, to yield a separate <NUM>-bit MSB component of low spatial frequency/high brightness from the input HDR signal (step <NUM> may be similar to <NUM> in <FIG>). (Note that the example of a <NUM>-bit HDR signal that is divided between an <NUM>-bit MSB component and a <NUM>-bit LSB component does not fall within the scope of the claims, but a <NUM>-bit HDR signal that is divided between an <NUM>-bit MSB component and a <NUM>-bit LSB component and includes a further two-bits between the MSB component and the LSB component would fall within the scope of the claims. ) As shown in <FIG> at step <NUM>, the image processor <NUM> may further be configured to process the signal using a local dimming algorithm that is configured to perform uniformity correction (by using a high spatial frequency modulation of the processed HDR signal to correct for brightness uniformity), brightness detail compensation (by using an anti-aliasing algorithm to smooth our transitions in the high brightness processed HDR signal) and to perform Gamma correction (by using Electro-Optical Transfer Function according to standard HDR decoding). The image processor <NUM>, at step <NUM>, outputs the LSB component of the HDR signal via a connection <NUM> to a standard dynamic range projector <NUM> (similar to projector <NUM> in <FIG>) that is configured to project the LSB component imagery onto the front of a display screen <NUM> (similar to screen <NUM> in <FIG>). The image processor <NUM>, at step <NUM>, outputs the MSB component of the HDR signal via a connection <NUM> to a high brightness LED zonal illuminator <NUM> that is configured to project the MSB component imagery onto the back of the display screen <NUM>. The separated LSB component and MSB component are then optically combined by projecting the LSB component onto the front side of the screen <NUM> and the MSB component onto the back side of the same screen <NUM>, where the MSB component is the properly weighted to the light projected onto the front side of the screen. The standard dynamic range projector <NUM> may be a Low Dynamic Range LDR projector, for example, which at step <NUM>, projects the LSB component imagery of high spatial frequency/low brightness onto the front of the display screen <NUM>. The high brightness illuminator <NUM> may be a high brightness zonal illuminator LED projection array <NUM> that, at step <NUM>, projects the MSB component imagery of low spatial frequency/high brightness onto the back of the display screen <NUM>. In some examples, the system <NUM> is incorporated in a flight simulator display, to project the separate LSB component onto the front of a simulator display screen, and to project the separate MSB component onto the back of the simulator display screen, to provide improved display of HDR image data in a flight simulator system at a cost advantage to more expensive HDR digital projectors.

Claim 1:
A method (<NUM>) for projecting an image on a screen (<NUM>, <NUM>), the method comprising:
processing (<NUM>, <NUM>, <NUM>, <NUM>) an X bit high-dynamic range video signal (<NUM>, <NUM>) using an image processing device (<NUM>, <NUM>) executing a local dimming algorithm that performs bit separation and scaling (<NUM>, <NUM>, <NUM>, <NUM>) to convert the high dynamic range video signal (<NUM>, <NUM>) into a binary weighted digital byte to derive a separate Y bit Least-Significant-Bit (LSB) component (<NUM>, <NUM>) comprising consecutive bits of high spatial frequency/low brightness including the least-significant-bit of the X-bit high-dynamic range video signal and an N bit Most-Significant-Bit (MSB) component (<NUM>, <NUM>) comprising consecutive bits of low spatial frequency/high brightness including the most-significant-bit of the X-bit high-dynamic range video signal that are scaled with a brightness weighting, wherein X, Y and N are integers;
characterized in that X > N + Y; and in that the method further comprises:
projecting (<NUM>, <NUM>) the LSB component (<NUM>, <NUM>) of the image onto a front (<NUM>) of the screen (<NUM>, <NUM>) with a standard dynamic range (SDR) projector; and
projecting (<NUM>, <NUM>) the MSB component (<NUM>, <NUM>) of the image onto a back (<NUM>) of the screen (<NUM>, <NUM>) using a high intensity light source (<NUM>, <NUM>).