HK1108756B - Rapid image rendering on dual-modulator displays - Google Patents

Description

Fast image rendering on dual modulator display

Cross reference to related applications

This application claims priority from U.S. patent application No.60/591,829 "RAPID FRAME RENDERING FOR HIGHDYMAMIC RANGE DISPLAYS", filed on 7/27/2004. FOR the case of the united states, the present application claims benefit under 2004, 7/month, 27/month, No.60/591,829, "RAPIDFRAME RENDERING FOR HIGH DYMAMIC RANGE DISPLAYS" in accordance with 35u.s.c. § 119.

Technical Field

The present invention relates to a system and method for displaying images on a display of the type having two modulators. A first modulator produces a light pattern and a second modulator modulates the light pattern produced by the first modulator to produce an image.

Background

International patent application WO02/069030 published on 6/9/2002 and WO03/077013 published on 18/9/2003, both of which are incorporated herein by reference, disclose a display having a modulated light source layer and a modulated display layer. The modulated light source layer is driven to produce a lower resolution image representation. The low resolution representation is modulated by the display layer to provide an image at a higher resolution viewable by a viewer. The light source layer may comprise a matrix of actively modulated light sources such as Light Emitting Diodes (LEDs). The display layer positioned in front of and aligned with the light source layer may be a Liquid Crystal Display (LCD).

If the two layers have different spatial resolutions (e.g., the resolution of the light source layer may be about 0.1% of the resolution of the display layer), then both the software correction method and the psychological response (e.g., masking the luminance) may prevent the viewer from seeing a resolution mismatch.

Electronic systems for driving light modulators such as LEDs or LCD panels are well known to those skilled in the art. For example, LCD computer monitors and televisions are commercially available. Such displays and televisions include circuitry for controlling the amount of light transmitted by each pixel on the LCD panel. The task of deriving the drive from the image data signal to control the light source layer and the display layer can be computationally expensive. The acquisition of such signals may be performed by the processor of the video/graphics card of the computer or by some other suitable processor integrated into the computer, to the display itself or to an auxiliary device.

The task of deriving from the image data signals to control the light source layer and the display layer can be computationally expensive. Obtaining such a signal may be performed by the processor of the video/graphics card of the computer or by some other suitable processor integrated into the computer, display or auxiliary device. The performance limitations of the processor may undesirably limit the rate at which successive image frames may be displayed. For example, if the processor's capability is insufficient to process incoming video data at the frame rate of the video data, then the viewer may detect a pause between successive video image frames as small as a movie. This can distract the observer and negatively impact the observer's image viewing experience.

There is a need for a practical, cost-effective and efficient display system for displaying images on a display of the general type described above.

Drawings

The drawings show non-limiting embodiments of the invention.

The diagram of fig. 1 depicts the segmentation of the Point Spread Function (PSF) into narrow and wide gaussian-based segments.

The diagrams of fig. 2A, 2B and 2C depict the 16-bit Point Spread Function (PSF) split into 2 8-bit (high and low byte) segments.

The diagram of fig. 3 depicts the transitional behavior of the 8-bit high and low byte point spread function values with respect to the 16-bit range.

The diagram of fig. 4 depicts high and low byte point spread functions corresponding to the point spread function depicted in fig. 1.

The diagram of fig. 5 depicts the application of an iteratively derived interpolation function, i.e. to derive an interpolated Effective Luminance Pattern (ELP) that closely approximates the actual Effective Luminance Pattern (ELP).

Fig. 6 is a schematic diagram of a display.

FIG. 7 is a flow chart representing a method for displaying an image on a display having a controllable light source layer and a controllable display layer.

Fig. 8 is a flow chart illustrating a method of determining an effective luminance pattern.

Fig. 9 is a flow chart illustrating a method of determining an effective luminance pattern or determining an effective luminance pattern component.

Description of the invention

Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the present invention. However, the practice of the present invention may not require these particulars. In other instances, well-known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

The invention is applicable to a wide range of fields in which an image is displayed by generating a light pattern that is determined, at least in part, by image data, and modulating the light pattern to generate the image. The light pattern may be generated by any suitable device. Some examples include:

● are a plurality of light sources driven by a driver circuit that allows the brightness of the light sources to be varied.

● in combination with a reflective or transmissive modulator that modulates the light emitted by the light source.

The following description relates to non-limiting exemplary embodiments in which a light pattern is generated by an array of LEDs on one side of an LCD panel, and the LCD panel is controlled to modulate the light of the light pattern to produce a viewable image. In this example, it is contemplated that the LED array constitutes a first modulator and the LCD panel constitutes a second modulator.

Typically, rendering an image frame or group of frames for display on an LED/LCD layer display is accompanied by the following calculation steps:

1. acquiring image data (full screen or partial screen image data)

2. Appropriate drive values are derived from the image data for each LED of the first modulator using appropriate techniques (which may be, for example, nearest neighbor interpolation based on factors such as intensity and color) well known to those skilled in the art.

3. Using the derived LED drive values and the LED point spread function on the LED layer and the characteristics of any layers between the LED layer and the LCD layer, an effective luminance pattern is determined, the result of which pattern will be on the LCD layer when the LED drive values are applied to the LED layer.

4. Then, an image defined by the image data is divided by an effective luminance pattern to obtain coarse modulation data of the LCD layer.

5. In some cases, the coarse modulation data is modified to cause problems such as non-linearity or other artifacts that occur in the LED or LCD layers. These problems can be addressed using appropriate techniques (e.g., measurement, gamma correction, value substitution operations, etc.) well known to those skilled in the art. For example, generating modified modulation data may involve changing the coarse modulation data to match a gamma correction curve or other specific characteristics of the LCD layer.

6. Finally, the modulation data for the LCD (which may be coarse modulation data or modified modulation data) and the LED driving data are used to drive the LCD and LED layers to produce the desired image.

Various methods of reducing the computational cost of generating final modulation data for displaying an image are described herein. These methods include:

● in a lower precision domain, performing at least some partial computation (e.g., computing in the 8-bit domain, rather than the 16-bit domain); and is

● are implemented as one or more options effective to establish an effective luminance pattern as described herein.

Although these techniques may be implemented individually, any combination of the techniques described herein may be used.

Determination of an effective luminance pattern

The point spread function of each LED within an LED layer is determined by the geometric properties of that LED. A simple technique for determining the overall effective luminance pattern of the LED layers is to initially multiply the point spread function of each LED (specifically, the point spread function of the light emitted by the LED and passing through all optical structures between the LED and the LCD layers) by the selected LED drive value and an appropriate scaling parameter to obtain the effective luminance contribution to the LED of each pixel on the LCD layer for that drive value.

In this way, the luminance contribution of each LED within the LED layer may be determined and summed to obtain a total effective luminance pattern across the LED layer that results when the selected drive value is applied to the LED layer. However, these multiplication and addition operations are computationally expensive (i.e., time consuming) because to facilitate the division operation of step 4 above, the effective luminance pattern must be determined to be the same spatial resolution as the LCD layer.

The computational expense is particularly great if the point spread function of the LED has a very wide "support". The "support" of an LED point spread function is the number of LCD pixels illuminated by the LED in a non-negligible amount. The support can be defined by means of radii measured in the pixels of the LED layer, where the LED point spread function becomes so small that it is imperceptible to an observer. The support corresponds to a number of LCD pixels being illuminated by each LED in an effective amount.

For example, consider a hexagonal LED array in which the center of each LED is spaced from the immediately adjacent LED by a distance equal to 50 LCD layer pixels. If each LED has a point spread function with the support of 150 LCD pixels, then each pixel in the central portion of the LCD layer will be illuminated by light from approximately 35 LEDs. Thus, for this example, the calculation of the effective luminance pattern requires 35 operations for each pixel of the LCD layer in order to determine the amount of light each associated LED contributes to each pixel. Where the LCD layers have high spatial resolution, such calculations are very expensive (i.e., time consuming).

Resolution reduction

The time required to determine the effective luminance pattern produced on the LCD can be reduced by calculating the effective luminance pattern at a reduced spatial resolution, which is lower than the resolution of the high resolution image appearing on the LCD layer. This is possible because the point spread function of the individual light sources is usually smoothly varying. Therefore, the effective luminance pattern changes relatively slowly at the resolution of the LCD. Thus, the effective luminance pattern can be calculated at a lower resolution and scaled to the desired high resolution without causing significant artifacts.

Scaling (scaling) may be performed using suitable linear, gaussian or other interpolation techniques. Such a reduction in spatial resolution results in an approximately linear reduction in the computational effort to establish the effective luminance pattern. Many available interpolation methods for scaling up the effective luminance pattern calculated at a low resolution are computationally economical compared to the cost of calculating the effective luminance pattern at the resolution of the LCD or another second light modulator.

With the foregoing example, a 10-fold reduction in resolution in both the width and height directions yields an approximately 100-fold reduction in computational expense. This is because the total number of pixels in the reduced resolution image is 100 times less than the total number of pixels in the high resolution image that appear on the LCD layer. Each pixel of the reduced resolution image still receives light from 35 LEDs and 35 calculations per pixel are necessary, but these calculations apply to 100 times fewer pixels than if the calculations were performed separately for each pixel in the actual high resolution image appearing on the LCD layer.

Point spread function decomposition

The computational cost of the image rendering may also be reduced by decomposing the point spread function of each light source (e.g., each LED) into several components (e.g., by performing a gaussian decomposition), in which all components are recombined to produce the original point spread function. The effective luminance pattern for each component can then be determined separately. Once the effective luminance pattern is determined for each component, those effective luminance patterns can be combined to produce an overall effective luminance pattern. For example, the combination may be performed by addition.

As described above, the calculation of the effective luminance pattern contributed by each component may be performed at the resolution of the LCD layer or at a reduced resolution.

Since hardware components that are particularly suited for performing fast operations based on standard point spread functions (e.g., gaussian point spread functions) are commercially available, fast benefits can be obtained even if the effective luminance pattern is calculated for each component at the resolution of the LCD layer. Such hardware components are typically not commercially available for the non-standard point spread functions typical of actual LEDs within the LED layer of a display, and thus must resort to rather slow computational techniques using general purpose processors.

Greater speedy benefits can be achieved if the resolution reduction technique described above is used to determine the effective luminance pattern of each portion. Furthermore, different spatial resolutions may be used for different components of the point spread function to produce greater speedy benefits. For example, fig. 1 (solid line) depicts an exemplary LED point spread function having a steep center portion 10 and a wide tail portion 12. In this case, the actual point spread function can be decomposed into a narrow-based gaussian component 14A and a wide-based gaussian component 14B as described.

The wide-base gaussian component 14B (dashed line) contributes less to the image intensity than the narrow-base gaussian segment 14B. In addition, the wide-base gaussian component 14B changes more slowly than the narrow-base gaussian component 14A. Thus, the effective luminance pattern for narrow-based gaussian component 14A can be determined at a higher spatial resolution, while the effective luminance pattern for wide-based gaussian component 14B can be determined at a relatively lower spatial resolution. This preserves a significant portion of the image intensity information contained in the narrow base gaussian component 14A and is still relatively fast since the effective support of the narrow base gaussian segment is small and few LCD pixels are covered by that component. Conversely, since wide-base gaussian component 14B contains relatively small image intensity information, the component can be processed relatively quickly at low resolution without substantially reducing the resolution of the overall effective luminance pattern produced by combining the patterns derived for each component.

8 bit split

Image data is typically provided in the form of 16-bit words. High-end (i.e., more expensive) graphics processors typically perform computations in the 16-bit domain. Such processors may have dedicated 16-bit or floating-point arithmetic units that are capable of performing 16-bit operations quickly. The need for a high-end processor that can quickly perform 16-bit operations can be alleviated by computing the effective luminance pattern in the 8-bit domain. Such calculations can be reasonably performed by a less expensive processor.

Each LED point spread function is a two-dimensional function of intensity versus distance from the center of the LED. Such a point spread function may be characterized by a plurality of 16-bit data words. Wherein, the point spread function is expressed by a lookup table, and a plurality of 16-bit values are required to define the point spread function; for example, a value may be provided for each LCD pixel located on or within a circle centered on the LED and having a radius corresponding to the support of the radius of the point spread function.

Each of these 16-bit data words has an 8-bit high byte component and an 8-bit low byte component (any one 16-bit value a may be split into two 8-bit values B and C, such that a ═ B × 2⁸+ C, where B is the "high byte" and C is the "low byte"). The 8-bit value is preferably extracted only after all necessary scaling and processing operations have been applied to the input 16-bit data. FIG. 2A depicts a 16-site spread function; fig. 2B and 2C depict the 8-bit high and low byte components, respectively, of the locus expansion function of fig. 2a 16.

A 16-bit data word can represent a sub-2⁰-1 to 2¹⁶-an integer value of 1 (i.e., from 0 to 65535). An 8-bit word can represent from 2⁰-1 to 2⁸-an integer value of 1 (i.e. from 0 to 255). The "support" (as defined above) of the point spread function characterized by the 8-bit high byte component is much smaller (narrower) than the support of the entire point spread function. This is because when the 16-bit data word characterizing the point spread function as a whole reaches 255 values out of the range of 65535 possible values, the 8-bit high byte component reaches its lowest value of the 255 possible values (zero). The remaining 255 values are provided by the low byte component with the high byte component value equal to zero. So that the effective luminance pattern corresponding to the narrow base 8-bit high byte component can be determined quickly without substantial loss of image intensity information. Resolution reduction and/or other techniques described above further speed up the determination of the effective luminance pattern for the 8-bit high byte component.

The support of the point spread function characterized by an 8-bit low byte component is quite broad. Specifically, although the 8-bit low-byte component has only 255 possible values, those values are reduced from 255 to 0 (resulting from 65535 values as a whole point spread function), and those 255 values correspond to the 255 lowest intensity levels (i.e., in terms of this level, the value of the high-byte component is equal to 0). Those 255 levels represent the values of the point spread function in its peripheral part.

The low byte component may be divided into two regions. A central region within the boundary where the point spread function described by the high byte component reaches zero. In the central region, if the original 16-site spread function is fairly smooth, the low-byte components typically change in an irregular saw-tooth pattern (as depicted in FIG. 3). This is because, in the central region, the portion of the point spread function described by the low byte component is increased by the portion of the point spread function described by the high byte component.

For example, consider a transition from a 16-bit value 10239 to a 16-bit value 9728. The 16-bit value 10239 has a high byte component value of 39 and a low byte component value of 255 (i.e., 39 x 256+255 x 10239). Thus, the contribution of this low byte component to the point spread function is initially 255, while the contribution of the high byte component is initially 39. The contribution of the high byte component remains at 39 while the contribution of the low byte component drops smoothly from 255 to 0-at which point the original 16-site spread function has a value of 9984 (i.e., 39 x 256+ 0). The contribution of the high byte component to the point spread function then changes smoothly from 39 to 38, but this change is accompanied by a sudden change (from 255 to 0) in the contribution of the low byte component to the point spread function.

As can be seen in fig. 4, within the original point spread function radius R (and where the contribution value of the high byte component to the point spread function is non-zero), the resulting saw-tooth pattern of the contribution of the low byte component to the point spread function is characteristic of the original point spread function. Outside the radius R, the contribution value of the high byte component to the point spread function is zero, and the contribution value of the low byte component to the point spread function varies smoothly.

The contributions of the low-byte components of the point-spread function can be processed differently in these two regions (i.e. the inner and outer regions of radius R) to avoid unwanted artifacts. For example, keeping a substantial portion of the image intensity information contained in the region inside the radius R, the effective luminance pattern is preferably determined for this region, using the same relatively high resolution that was used to determine the high byte component contribution to the point spread function as previously described. Conversely, the effective luminance pattern for regions outside the radius R can be determined using a much lower resolution without substantial loss of image intensity information.

After the three point spread function segments (i.e., the high byte component, the low byte component region within radius R and the low byte component region outside radius R) have been processed as described above, the results are individually upsampled to match the resolution of the LED layers and then recombined with the appropriate scaling factor used. A typical combination involves summing the values of the two low byte component regions with the value of the high byte component after multiplying the value of the high byte component by 256.

Interpolation

If the effective luminance pattern value is determined using a resolution lower than the resolution of the LCD layer, the value must be upsampled to match the resolution of the LCD layer. Interpolation techniques for upsampling low resolution images to high resolution images are well known, and linear and gaussian based techniques are well known. While this prior art technique can be used in conjunction with the above techniques, the use of interpolation techniques optimized for a particular display configuration can improve accuracy or speed, or both. Optimization facilitates higher resolution image compression, minimizes the introduction of undesirable insertion artifacts, and reduces image presentation time. In the extreme case, interpolation techniques can be used to reduce the effective luminance pattern resolution to match that of the LED layers.

Existing interpolation techniques are often limited to use with specific pre-interpolation data, or to use with specific interpolation functions. The interpolation technique used to match the resolution of the effective luminance pattern to that of the LCD display need not satisfy such a constraint, so long as the convolution of the pre-interpolation data with the selected interpolation function will produce an effective luminance pattern that has sufficient similarity to the actual effective luminance pattern.

The required similarity depends on the display application. Different applications require different degrees of similarity-in some applications, relatively small deviations may unacceptably distract the viewer, while larger deviations may be tolerable in other applications (e.g., applications involving television or computer game images, where relatively large deviations simply produce images of acceptable quality to most viewers). It is therefore not necessary to apply interpolation techniques directly to the actual LED drive values, or to the actual LED point spread function.

For example, FIG. 5 depicts the results obtained by reducing the resolution of the effective luminance pattern to match the LED layer resolution using an iteratively derived interpolation technique. The pixel values at the resolution of the LED layer are not the LED drive values-they are the luminance values of the effective luminance pattern before interpolation. The interpolation function may be determined using standard iterative methods and random start conditions. As seen in fig. 5, the convolution of the iteratively derived interpolation function with the effective luminance pattern values yields results that are fairly close to the actual effective luminance pattern.

Many different interpolation techniques may be used. No correlation is required between the interpolation function and the point spread function of the LED, the LED drive values, or any other display characteristic, so long as the interpolation function is selected and the input parameters selected for use with the function produce results that are reasonably close to the actual effective luminance pattern.

Exemplary embodiments

Fig. 6 illustrates certain exemplary embodiments of the present invention. Fig. 6 shows a display 30 comprising a modulated light source layer 32 and a display layer 34. For example, light source layer 32 may include:

● controllable light source arrays such as LEDs;

● a fixed intensity light source and a light modulator configured to spatially modulate the intensity of light from the light source;

● some combination of these means.

In the illustrated device, the light source layer 32 includes an array of LEDs 33.

Display layer 34 includes a light modulator that further spatially modulates the intensity incident on display layer 34 from light source layer 32. For example, display layer 34 may include an LCD panel or other transmissive light modulator. Display layer 34 typically has a higher resolution than light source layer 32. A light structure 36 suitable for transmitting light from light source layer 32 to display layer 34 may be provided between light source layer 32 and display layer 34. The light structure 36 may include elements such as voids, light diffusers, collimators, and the like.

In the illustrated arrangement, controller 40 includes a data processor 42 and appropriate interface electronics, with 44A for controlling light source layer 32 and 44B for controlling display layer 34, which receives image data 46 defining an image to be displayed on display 30. Controller 40 drives the light emitters (e.g., LEDs 33) of light source layer 34 and pixels 35 of display layer 34 to produce a desired image for viewing by an individual or multiple persons. The program memory 46, accessible to the processor 42, contains software instructions that, when executed by the processor 42, cause the processor 42 to perform the methods described herein.

Controller 40 may comprise a suitably programmed computer having suitable software/hardware interfaces for controlling light source layer 32 and display layer 34 to display an image defined by image data 48.

Fig. 7 illustrates a method 50 of displaying image data on a display of the general type shown in fig. 6. Method 50 begins with receiving image data 48 at block 52. In block 54, first drive signals for light source layer 32 are derived from image data 48. Suitable known methods may be used to obtain the first drive signal at block 54.

In block 56, method 50 calculates an effective luminance pattern. The effective luminance pattern may be calculated from the first drive signal and a known point spread function for the light source of light source layer 32. Block 56 calculates the effective luminance pattern at a resolution lower than the resolution of the display layer 34. For example, block 56 may calculate the effective luminance pattern at each dimension by a factor that is less than 4 or less than the resolution of display layer 34 (in some embodiments, factors for each dimension range from 4 to 16 less).

In block 60, the effective luminance pattern calculated in block 58 is upsampled to the resolution of the display layer 34. This may be achieved by using, for example, any suitable interpolation technique. In block 62, a second drive signal for the display layer is determined from the upsampled effective luminance pattern and the image data. The second drive signal may also take into account known characteristics of the display layer and any desired image correction, color correction, etc.

At block 64, the first drive signals derived in block 54 are applied to the light source layer and the second drive signals derived in block 62 are applied to the display layer to display an image for viewing.

Fig. 8 illustrates a method 70 for calculating an effective luminance pattern. The method 70 may be used within block 56 of the method 50 or applied to other applications. Method 70 begins by calculating the ELP for each component of the point spread function of the light sources of light source layer 32 (blocks 72A, 72B, and 72C — collectively block 72). The blocks 72 can be performed in any order or in parallel with one another. Fig. 8 shows three PSF components 73A, 73B and 73C and three corresponding blocks 72. The method may be implemented by two or more PSF components 73.

The components of the Point Spread Function (PSF) are typically predetermined. A representation of each component is stored in a location accessible to processor 42. For each light source of light source layer 32, each of blocks 72 may include multiplying the value defining the point spread function component by a value representing the intensity of the light source. In block 74, the effective luminance patterns determined in block 72 are combined, e.g., by summing, to produce a total estimate of the effective luminance pattern, which is produced by applying the first drive signal to the light source layer 32.

Fig. 9 illustrates a method 80 that may be used to calculate an effective luminance pattern. The method 80 may be applied to:

● calculating the effective luminance pattern of method 50 in block 56; or

● calculating effective luminance patterns for the components of the point spread function in block 72 of method 70; or

● apply to other applications.

Method 80 begins at block 82 with data that plots a point spread function (or a PSF component) of the light sources of light source layer 32, and data that indicates at what intensity the light sources can operate under control of the first drive signal. The method 80 combines these values together (e.g., multiplies them together) to obtain a set of values characterizing the contribution of the light source to the effective luminance pattern for various spatial locations.

Block 84 obtains the high order and low order components of the resulting value. In some embodiments, the result value is a 16-bit word, the high-order component is an 8-bit byte, and the low-order component is an 8-bit byte.

The contribution to ELP is determined for the high and low order components in blocks 86 and 88, respectively. For each light source, the support area whose value is contained in the high-order contribution of 86 is generally significantly smaller than the support area whose value is contained in the low-order contribution of block 88.

Block 88 generally calculates the low-order contribution separately for points located within the support area of the high-order contribution (block 90) and for points located outside the support area of the high-order contribution (block 92). Blocks 86, 90, and 92 may be performed in any order or simultaneously.

In block 94, the contributions from blocks 86, 90, and 92 are combined together to produce an overall ELP. Where the high and low order components are 8-bit bytes or less, the computations in blocks 86, 90, and 92 may be performed predominantly or entirely in the 8-bit domain (i.e., using 8-bit operations on 8-bit operands).

Certain implementations of the invention include a computer processor that executes software instructions that cause the processor to perform the methods of the invention. For example, one or more processors in a computer or other display controller may implement the methods described in fig. 7, 8, and 9 by executing software instructions in a program memory accessible to the processors. The present invention may also be provided as a program product. The program product may comprise any medium carrying a set of computer-readable signals comprising instructions which, when executed by a data processor, cause the data processor to carry out the inventive methods. The program product according to the invention may be of any varying form. For example, the program product may include physical media such as magnetic data storage media, including floppy disks, hard disk drives; optical data storage media including CD ROM and DVD, electronic data storage media including ROM, flash RAM, etc.; or a transmission type medium such as a digital or analog communication link. The computer-readable signal on the program product may optionally be compressed or encrypted.

Where a component (e.g., a part, section, assembly, device, processor, controller, collimator, circuit, etc.) is referred to above, unless otherwise indicated, reference to that component (including a reference to a "means") should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.

It will be apparent to those skilled in the art from this disclosure that many alternatives and modifications are possible in the practice of the invention without departing from the spirit or scope thereof, for example:

● the light source layer may include many different types of light sources that may have different point spread functions from one another.

● the display may include a color display and the calculations described above may be performed separately for each of the plurality of colors.

While several exemplary embodiments and examples have been discussed above, those skilled in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true scope.

Claims (28)

1. A method for displaying an image on a display, the display comprising a light source layer and a display layer, the method comprising:

determining a driving value for a light source of the light source layer;

determining an effective luminance pattern of the light source layer at a first spatial resolution lower than a spatial resolution of the display layer; and

the spatial resolution of the effective luminance pattern is increased to a second spatial resolution corresponding to the resolution of the display layer.

2. A method according to claim 1, wherein the resolution of the display layer is at least 4 times the resolution used to determine the effective luminance pattern in at least one dimension.

3. A method according to claim 2, wherein the resolution of the display layer in each of the two dimensions is at least 8 times the resolution used to determine the effective luminance pattern.

4. The method of claim 1, wherein increasing the spatial resolution of the effective luminance pattern comprises performing interpolation on data defining the effective luminance pattern.

5. The method of claim 2, wherein increasing the spatial resolution of the effective luminance pattern comprises performing interpolation on data defining the effective luminance pattern.

6. A method according to claim 3 wherein increasing the spatial resolution of the effective luminance pattern comprises performing interpolation on the data defining the effective luminance pattern.

7. The method of any one of claims 1 to 6, wherein determining the effective luminance pattern of the light source layer comprises:

determining a contribution to the effective luminance pattern for each of the components of the point spread function of the light sources of the light source layer; and

the contribution of each component to the effective luminance pattern is combined.

8. The method of claim 7, wherein each component is a gaussian component.

9. The method of claim 7, wherein the point spread function is the sum of all components of the multi-component.

10. The method of claim 7, wherein each component is represented at the first spatial resolution.

11. The method of claim 7, wherein two or more of the components are represented at different spatial resolutions from each other.

12. The method of claim 10, increasing the spatial resolution of each component to a second spatial resolution before combining the contributions to the effective luminance pattern.

13. The method of claim 11, increasing the spatial resolution of each component to a second spatial resolution before combining the contributions to the effective luminance pattern.

14. The method of claim 7, wherein combining the contributions to the effective luminance pattern comprises applying a mathematical inverse to the applied operation to decompose the point spread function into multiple components.

15. The method of claim 7, wherein determining the contribution to the effective luminance pattern for each of the plurality of components of the point spread function is performed over different support regions for each of the two components of the point spread function.

16. The method of claim 10, wherein determining the contribution to the effective luminance pattern for each of the plurality of components of the point spread function is performed over different support regions for each of the two components of the point spread function.

17. The method of claim 11, wherein determining the contribution to the effective luminance pattern for each of the plurality of components of the point spread function is performed over different support regions for each of the two components of the point spread function.

18. The method of claim 12, wherein determining the contribution to the effective luminance pattern for each of the plurality of components of the point spread function is performed over different support regions for each of the two components of the point spread function.

19. A method according to any one of claims 1 to 6 wherein determining the effective luminance pattern of the light source layer comprises:

for each of a plurality of light sources of the light source layer:

determining contributions of high-order and low-order components of a set of point spread function values to the effective luminance mode, respectively; and

the contribution of the high-order and low-order point spread function values to the effective luminance pattern is combined.

20. The method of claim 7, wherein determining the effective luminance pattern of the light source layer comprises:

for each of a plurality of light sources of the light source layer:

determining contributions of high-order and low-order components of a set of point spread function values to the effective luminance mode, respectively; and

the contribution of the high-order and low-order point spread function values to the effective luminance pattern is combined.

21. The method of claim 19, wherein the point spread function values comprise 16-bit words and the high-order and low-order portions of the set of point spread function values comprise 8-bit words.

22. The method of claim 19, wherein determining the contribution to the effective luminance mode of the high-order and low-order portions of the set of point spread function values is performed over a larger support area of the low-order portion of the set of point spread function values than the support area of the high-order portion of the set of point spread function values.

23. The method of claim 22, wherein determining the contribution of the low-order part of the set of point spread function values to the effective luminance pattern comprises determining the contribution of each of:

the intersection of the high-order and low-order partial support regions of the point spread function value; and

the higher order part of the point spread function value supports the area part of the lower order part of the point spread function value outside the area supported.

24. The method of claim 19 including identifying a higher order part support region for the point spread function value by determining a radius R where the point spread function for the higher order part of the point spread function value equals zero.

25. The method of claim 19, comprising determining the contribution of the lower-order part of the set of point spread function values to the effective luminance pattern at different resolutions inside and outside of a region supported by the higher-order part of the point spread function values.

26. The method of claim 20, comprising determining the contribution of the lower-order part of the set of point spread function values to the effective luminance pattern at different resolutions inside and outside of a region supported by the higher-order part of the point spread function values.

27. The method of claim 25, comprising determining the contribution of the low-order part of the set of point spread function values to the effective luminance mode at a high resolution within the support area of the high-order part of the point spread function value and at a low resolution outside the support area of the high-order part of the point spread function.

28. The method of claim 26, comprising determining the contribution of the lower-order part of the set of point spread function values to the effective luminance pattern at different resolutions within and outside a support region of the higher-order part of the point spread function values.