1. Field of invention.

The present invention generally relates to the reconstruction of high- dynamic-range pictures, !n particular, the technical field of the present invention is related to the reconstruction of a high-dynamic-range picture from two low-dynamic-range pictures generated by a dual modulation which takes a high dynamic range picture as input.

2. Technical background.

This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

Low-dynamic-range pictures (LDR pictures) are pictures whose luminance values are represented with a limited number of bits (most often 8, 10 or 12 bits). This limited representation does not allow to correctly render small signal variations, in particular in dark and bright luminance's ranges. In High-Dynamic-Range pictures (HDR pictures), the signal representation is extended in order to keep a high accuracy of the signal on its entire range. In HDR pictures, pixels' value are usually represented in floating-point format (either 32-bit or 16-bit for each component), the most popular format being openEXR half-float format (16-bit per RGB component, i.e. 48 bits per pixel).

Dual modulation methods are usually used in the dual modulation HDR displays. Such dual modulation HDR displays are made of two panels:

- one LED panel as a backlight panel that generates low resolution luminance picture of the scene; and - one LCD panel that modulates the light coming from the LED panel to generate the resulting HDR picture.

In order to feed those two panels, a HDR picture is decomposed in two separate LDR pictures by help of a so-called dual modulation: a first picture (usually called a LCD picture) which is a low dynamic range version of the high-dynamic-range picture and a second picture (usually called a LED picture) which is a low-resolution version of the luminance component of the high-dynamic-range picture.

Several dual-modulation decompositions have been developed to address this issue, for instance in [Sewoong Oh, "High Dynamic Range Image Encoding for BrightSide Display", Department of Electrical Engineering, Stanford University] and [Helge Seetzen, "High Dynamic Range Display and Projection systems", thesis, University of British Columbia. Vancouver. April 2009] p. 75.).

Dual-modulation-HDR displays have the ability to display content with luminance values up to 4000 cd/m2. Such luminance values are useful to see details in bright areas if the display environment is bright (midday in a room with large windows) but can be very aggressive and disturbing if the display environment is dim (at night in a room with few ambiance light). Dual modulation HDR displays are also able to provide true blacks and lot of details in very dim scenes. Such details will be visible if the display environment is dim (at night in a room with few ambiance light) but won't be visible if the display environment is bright (midday in a room with large windows). These phenomena's are due to the eye capability to adapt to the environment average luminance. Thus HDR content shall be adapted to the illumination conditions of the environnemet around the display.

Moreover, the HDR content shall be adapted to end-user preferences. For example, a user may prefer brighter and dimmer content and have the option to select the correct HDR content relative brightness for example. 3. Summary of the invention.

The invention is aimed at alleviating at least one of the drawbacks of the prior art. To this aim, the invention relates to a method for generating two low-dynamic-range picture from a high-dynamic-range picture by help of a dual-modulation, one of said low-dynamic-range pictures, said first picture, being a low-dynamic-range version of the high-dynamic-range picture and the other of said low-dynamic-range pictures, said second picture, being a low-resolution version of the luminance component of the high-dynamic- range picture, the method is characterized in that the behavior of said dual- modulation is controlled by metadata received from a remote device.

According to an embodiment, the metadata are received following the transmission to the remote device of some metadata which are either relative to a characteristic of a dual-modulation HDR display or defined from data issued from sensors that inform on the illumination environment around the dual-modulation HDR display or defined according to the end-user preference.

According to an embodiment, the two low-dynamic-range picture are transmitted separately to the remote device.

According to an embodiment, the two low-dynamic-range pictures are transmitted over usual 8 bits channel usually used to transmit low-dynamic- range picture.

According to another of its aspects, the invention also relates to a method for reconstructing a high-dynamic-range picture by help of an inverse dual-modulation which combines together a first and a second picture to reconstruct said high-dynamic-range picture. Said first picture being a low- dynamic-range version of the high-dynamic-range picture and said second picture being a low-resolution version of the luminance component of the high-dynamic-range picture, the method is characterized in that the behavior of said inverse dual-modulation is controlled by metadata received from a remote device.

According to an embodiment, the two low-dynamic-range pictures are received separately. According to another of its aspects, the invention relates to an apparatus for generating two low-dynamic-range picture from a high- dynamic-range picture by help of dual-modulation means, said means being configured in order that one of said low-dynamic-range pictures, said first picture, is a low-dynamic-range version of the high-dynamic-range picture and the other of said low-dynamic-range pictures, said second picture, is a low-resolution version of the luminance component of the high-dynamic- range picture. The apparatus is characterized in that said dual-modulation means are controlled by metadata received from a remote device.

According to another of its aspects, the invention relates to an apparatus for reconstructing a high-dynamic-range picture by help of inverse dual-modulation means configured to combine together a first and a second picture in order to reconstruct said high-dynamic-range picture. Said first picture being a low-dynamic-range version of the high-dynamic-range picture and said second picture being a low-resolution version of the luminance component of the high-dynamic-range picture, the apparatus is characterized in that said inverse dual-modulation means are controlled by metadata received from a remote device.

The specific nature of the invention as well as other objects, advantages, features and uses of the invention will become evident from the following description of a preferred embodiment taken in conjunction with the accompanying drawings.

4. List of figures.

The embodiments will be described with reference to the following figures:

Fig. 1 shows a diagram which represents an embodiment of a dual modulation of a floating-point HDR picture.

Fig. 2 shows a diagram which represents an embodiment of an inverse dual-modulation used to reconstruct a floating-point HDR picture from a LDR and LED picture. Fig. 3 shows an embodiment of the invention implemented apparatuses of a communication system.

Fig. 4 shows an example of a VSDB.

Fig. 5 shows an example of a VSDB relative to specific metadata. Fig. 6 shows an example to carry out the LED picture as metadata. Fig. 7 shows an example of a SCDCS table to cary out metadata. Fig. 8 represents an exemplary architecture of a device 80.

5. Detailed description of a preferred embodiment of the invention.

The present invention will be described more fully herein-after with reference to the accompanying figures, in which embodiments of the invention are shown. This invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein. Accordingly, while the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims. Like numbers refer to like elements throughout the description of the figures.

The teminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising," "includes" and/or "including" when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components. but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Moreover, when an element is referred to as being "responsive" or "connected" to another element, it can be directly responsive or connected to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly responsive" or "directly connected" to another element, there are no intervening elements present. As used herein the term "and/or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as .

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the teachings of the disclosure.

Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows.

Some embodiments are described with regard to block diagrams and operational flowcharts in which each block represents a circuit element, module, or portion of code which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in other implementations, the function( s) noted in the blocks may occur out of the order noted. For example, two blocks shown in succession way, in fact, be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending on the functionality involved.

Reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

While not explicitly described, the present embodiments and variants may be employed in any combination or sub-combination.

Fig. 1 shows a diagram which represents an embodiment of a dual modulation of a floating-point HDR picture.

The goal of the dual modulation is to generate two low-dynamic-range pictures called a LED picture and a LCD picture from the floating-point HDR picture.

At step 11 , the minimal and the maximal value of the floating-point

HDR input picture are calculated.

At step 12, the floating-point HDR input picture is normalized between

[0..1 ]·

At step 13, the normalized picture is scaled to a max brightness value (for instance 4000 cd/m2). This produces a picture called "scale_RGB".

At step 14, the square root of the picture scale RGB is computed. At step 15, the luminance component Y of the square root of the picture scale_RGB is computed, for instance by Y = 0.2126xR + 0.7152xG + 0.0722xB where R,G and B are respectively the Red, Green and blue component of the square root of the picture scale_RGB.

At step 16, a blur function is applied (for instance a gaussian filter) to the luminance component Y in order to have a coarse representation of the luminance component that makes the further downsampling (step 17) to the LED grid more robust to peaks (noise).

At step 17, the coarse luminance component is downsampled to a resolution of a LED grid of a dual-modulation HDR display and the resulting component is scaled (step 18) in order to take into account a further convolution with a Point Spread Function (step 21 ) that will increase each luminance pixel value due to the additive process of the convolution.

At step 19, the resulting luminance component is scaled between

[0..255] in order to produce a low-resolution version of the luminance component of the high-dynamic-range picture which is called a LED picture. The minimal and maximal values of the LED picture are also calculated.

The luminance component, output of the step 18, is also used to reconstruct a full resolution backlight picture usually called LCD picture.

At step 20, the luminance component, output of the step 18, is copied on a full-size picture grid and each copied value is convoluted with a Point Spread Function (step 21 ).

At step 22, the resulting luminance component called rec-lum is then used to divide the picture scale_RGB to produce a RGB version of the HDR picture.

At step 23, the RGB version of the HDR picture is scaled between [0..255] in order to produce the LCD picture. The minimal and maximal values of the LCD picture are also calculated.

According to an embodiment, the Point Spread Function is a Gaussian filter which is characterized by a standard deviation (sigma) and the size in pixels of the picture representing the PSF. The Point Spread Function is given for example by:

where: x = CLsize of the picture and y = CLsize of the picture.

The max brightness value used in step 13, the resolution of the LED grid used at step 17, the full-size picture grid used in step 20 and the Point Spread function used in step 21 form a first set of metadata.

The metadata relative to the resolution of a LED grid of a dual- modulation HDR display may be a number of lines and a number of rows of a LED grid. The metadata relative to the Point Spread Function may be a standard deviation (sigma) of a Gaussian filter and the size in pixel of this Point spread Function for example.

According to a variant of the embodiment, the behavior of the dual- modulation is controlled by the first set of metadata.

According to a variant of the embodiment, the first set of metadata comprises at least one defaut value stored locally. According to a variant of the embodiment, the first set of metadata is received from a remote device.

The invention is not limited to the embodiment of the dua!-modulation described in Fig. 1 and any other dual-modulation may be used to generate the LCD and LED pictures. Moreover, the scope of the invention is not limited to the examples of metadata (first set of metadata) given in relation with the dual-modulation described in Fig. 1 but extends to any metadata which control the behavior of a dual-modulation.

Fig. 2 shows a diagram which represents an embodiment of an inverse dual-modulation used to reconstruct a floating-point HDR picture from a LDR and LED picture.

At step 24, the LCD picture is inverse scaled using the min and max LCD values calculated at the step 23 to generate a reconstructed version of the RGB version of the HDR picture called "inv-scale-RGB".

At step 25, the LED picture is inverse scaled using the minimal and maximal LED values calculated at step 19 to generate a reconstructed version of the scale LED picture.

As for the dual modulation, the reconstructed version of the scaled LED picture is used to reconstruct the full resolution backlight picture.

At step 26, the reconstructed version of the scale LED picture is copied on a full-size picture grid. The step 26 requires the resolution of the LED grid used in step 17.

At step 27, the output of step 26 is convoluted with the Point Spread Function used in the step 21.

At step 28, the output of step 27 which is a reconstructed version of the rec-lum (step 22) is multiplied by the picture "inv-scale-RGB" picture to generate the reconstructed RGB version of the HDR picture.

At step 29, the reconstructed RGB version of the HDR picture is normalized by dividing it by the max brightness value (for instance 4000 cd/m2) used in step 13. The output of step 29 is then de-normalized (step 30) using the min and max HDR values calculated at step 11 in order to generate a reconstructed version of the HDR picture.

According to the invention, the behavior of the inverse dual-modulation is controlled by metadata received from a remote device.

These metadata are called the second set of metadata in the following. For example, the second set of metadata (shown in Fig. 1 and 2) may define at least one item of the following list: the min and max LCD values calculated at the step 23, the minimal and maximal LED values calculated at step 19, the min and max HDR values calculated at step 11.

According to a variant, the second set of metadata may also comprises at least one item of the first set of metadata descrived above.

According to a variant, the second set of metadata comprises also the LED picture.

The invention is not limited to the embodiment of the inverse dual- modulation described in Fig. 2 and any other inverse dual-modulation may be used to reconstruct a HDR picture from the LCD and LED pictures. Moreover, the scope of the invention is not limited to the examples of metadata given in relation with the inverse dual-modulation described in Fig. 2 but extends to any metadata which control the behavior of an inverse dual- modulation.

Fig. 3 shows an embodiment of the invention implemented in apparatuses of a communication system.

This communication system is detailed in the following when two remote apparatuses A1 and A2 are configured to communicate to each other via at least one communication link or network NET. The apparatus A1 is called a transmitter and the apparatus A2 is called a receiver. However the invention is not limited to the use of a single transmitter but may be extended to multiple transmitters communicating with at least one receiver A2. Moreover, an apparatus A1 or A2 may be a single device or composed of multiple devices which communicate together to implement the same functions of either the apparatus A1 or A2 detailed in the following. The dual-modulation described in relation with Fig. 1 is implemented in the transmitter A1 and the inverse dual-modulation described in relation with Fig. 2 is implemented in the receiver A2.

According to an embodiment, the first set of metada is stored locally in the transmitter A1 or may be obtained from the floating-point HDR input picture, and the transmitter A1 is configured to send to the receiver A2 the first set of metadata. The receiver A2 is then configured to receive the first set of metadata sent by the transmitter A1 and to control the behavior of the inverse dual-modulation according to the received metadata.

Note that when some metadata which result of the execution of the dual modulation is not sent by the transmitter A1 , the receiver A2 may obtain this metadata from an internal storing memory.

According to an embodiment of the invention, the receiver A2 is configured to send to the transmitter A1 some metadata which are either relative to a characteristic of a dual-modulation HDR display or defined from data issued from sensors that inform on the illumination environment around the transmitter A1 (or a display) or defined according to the end-user preference. These metadata are called the third set of metadata in the following.

Some metadata of the third set of metadata may be relative to a characteristic of a dual-modulation HDR display. For example, they may be metadata of the first set of metadata.

According to this embodiment, the transmitter A1 is then configured to receive the third set of metadata and to control the behavior of the dual- modulation according to the received metadata.

This embodiment is advantageous because the receiver A2 has the ability to change dynamically the behavior of both the dual-modulation implemented by the transmitter A1 and the inverse dual-modulation implemented by the receiver A2 in order to optimize the rendering of the HDR picture on the dual-modulation HDR display. According to a variant, the transmitter A1 selects the most appropriate first set of metadata to control the dual-modulation from the received third set of metadata and sends this selected first set of metadata to the receiver A2.

According to a variant, the most appropriate set of first metadata is the the first set of metadata embedded in the received third set of metadata.

Optionally, the transmitter A1 is configured to receive occasionally or periodically a third set of metadata from the receiver A2 and the transmitter A1 is then configured either to select a new most appropriate first set of metadata from the last received third set of metadata and to send the selected first set of metadata to the receiver A2 or to consider the first set of metadata embedded in the last received third set of metadata to control the dual-modulation.

For example, an end-user may also prefer brighter and dimmer content and this may depend also on the environment around the display. So the end-user may have the option to select the correct HDR content relative brightness, for example, from an user interface of the receiver A2. This selection defines then a maximum brightness value which is embedded as metadata in the third set of metadata for example. Both the duai-modulation and the inverse dual-modulation takes then into account this new maximum brightness value.

According to a variant of the embodiment, the LCD and LED picture are transmitted separately, i.e. the LCD and LED pictures are transmitted by the transmitter A1 using different means and the receiver A2 receives the LCD and the LED picture from different means.

For example, the LCD picture is sent over a communication link or network as an active video data and the LED picture is sent over the communication link or network as metadata.

The term "separately" means that the metadata are not transmitted as a part of the transmitted active video data as well-known in prior art. In fact, in prior art, the LED picture data are directly inserted in the first pixels of the LCD picture, following a sync word, and the modified LCD picture is then sent over the communication link or network. Such a method is dedicated, for example, to a well-known "Sim2 HDR47" display. The main drawback is the lost of the two first lines of the LCD picture that are used to transmit the LED picture data.

The LCD picture and metadata (including the LED picture) may be sent over 8 bits channels usually used to transmit low-dynamic-range picture.

According to an example, given for illustrative purpose, the

apparatuses A1 and A2 communicate each other over a HDMI link

(http://en.wikipedia.org/wiki/HDMl, http://www.hdmi.org/).

Usually, the HDMI protocol between the transmitter A1 and the receiver A2 starts by a discovery phase : when the receiver A2 is connected to the transmitter A1 , or when you power on those already connected pieces of equipment, the transmitter A1 detects the receiver A2 and discovers it through the DDC (Display Data Channel) of the HDMI link. It's basically a way to have the transmitter A1 receiving metadata from the receiver A2.

The metadata may possibly comprise an information which informs the transmitter A1 whether the inverse dual-modulation is supported by the receiver A2.

Possibly, the metadata comprise also the third set of metadata as described above.

Then, for example, the transmitter A1 compares the receiver A2's capabilities (represented by metadata embedded in the received third set of metadata) with its own capabilities and selects the "most appropriate format" to drive and feed the receiver A2.

When the received information indicates that the receiver A2 supports the inverse dual-modulation, the transmitter A1 may consider the first set of metadata embedded in the received set of metadata to configure the dual- modulation. Other variants may be considered as explained above.

According to a variant, the VSDB (Vendor Specific Data Block) as defined by the HDMI forum is used to hold the metadata from the apparatus A2 to the apparatus A1 .

Fig. 4 shows an example of such VSDB. As we can see, the metadata may be carried either by feeding the "Rsvd(O)" bits by the metadata or by specifying a different length N to increase the VSDB payioad up to 32 bytes (including the header) and by feeding the "Reserved(O) bits.

Fig. 5 shows an example of a VSDB relative to specific metadata.

Fig. 6 shows an example to carry out the LED picture as metadata from the apparatus A1 to the apparatus A2. In this example, a VSIF (Vendor Specific InfoFrame defined by CEA-861 -F is used). The LED picture data are here designated by the term "dual modulation byte" in Fig. 6.

The 3 first bytes are the header as standardized by CEA 861 . Our payioad start at byte 3. The "number of LEDs per line" x "number of LEDs per column" dual modulation bytes will have to be broken down is 20 bytes packets. Each DM packet will be numbered by a 12b "continuation index".

HDMI version 2.0 provides two ways for the apparatus A2 to inform dynamically the apparatus A1 that end-user preferences and/or environments conditions have changed: either the CEC or the SCDCS.

Using the CEC, the apparatus A2 will whenever it needs send a to be defined specific CEC message to the apparatus A1 and using the SCDCS, the apparatus A1 will regularly poll the apparatus A2 to read the metadata from a SCDCS table defined by the HDMI 2.0. A specific entry for each metadata sent by the apparatus A2 has to be added to the SCDCS table defined by the HDMI 2.0 as shown in Fig. 7.

According to another example, the apparatuses A1 and A2

communicate each other using a packet based protocol such as defined by DisplayPort (http://en.wikipedia.org/wiki/DisplavPort,

http://www.displavDort.org/).

DisplayPort provides a discovery phase that is similar to the HDMI's one, thus allowing an equivalent exchange of metadata.

The packet based protocol uses a physical layer that carries data at a given bitrate that is higher than the raw data bitrate to be transmitted. For instance DisplayPort carries up to 4.32 Gb/s per lane providing 17.16 Gb/ ^' s bitrate for 4 lanes, which can be used to transmit 1080p 50Hz video that needs about 2.5 Gbps data rate for instance. The data are transmitted in asynchronous packets, i.e. carried data don't need to be transmitted synchronously at the video rate. These data can be transmitted in small data packets using high speed bursts of data that are buffered in the receiver.

The packets are typed as video packets, audio packets, control packets or other packets... In DisplayPort these packets are sent using the 4 "MLJane" lanes.

Here, a "LED packet" type is for example defined and LED packets are send from the apparatus A1 to the apparatus A2 on the 4 "MLJane" lanes.

Moreover, these packet based protocols generally implement a bidirectional additional channel used as a communication channel between the transmitter and the receiver.

In DisplayPort, the Auxiliary Channel "AUX CH" that is usually used to carry information as EDID for instance may be used to carry out the metadata from the apparatus A2 to the apparatus A1 .

On Fig. 1 -7, the modules are functional units, which may or not be in relation with distinguishable physical units. For example, these modules or some of them may be brought together in a unique component or circuit, or contribute to functionalities of a software. A contrario, some modules may potentially be composed of separate physical entities. The apparatus which are compatible with the inventbn are implemented using either pure hardware, for example using dedicated hardware such ASIC or FPGA or VLSI, respectively « Application Specific Integrated Circuit », « Field- Programmable Gate Array », « Very Large Scale Integration », or from several integrated electronic components embedded in a device or from a brend of hardware and software components.

Fig. 8 represents an exemplary architecture of a device 80.

Device 80 comprises following elements that are linked together by a data and address bus 81 :

- a microprocessor 82 (or CPU), which is, for example, a DSP (or Digital Signal Processor);

- a ROM (or Read Only Memory) 83; - a RAM (or Random Access Memory) 84;

- an I/O interface 85 for reception of data to transmit, from an application; and

- a battery 86

According to a variant, the battery 86 is external to the device. Each of these elements of Fig. 8 are well-known by those skilled in the art and won't be disclosed further. In each of mentioned memory, the word « register » used in the specification can correspond to area of small capacity (some bits) or to very large area (e.g. a whole program or large amount of received or data). ROM 83 comprises at least a program and parameters. Algorithm of the method according to the invention is stored in the ROM 83. When switched on, the CPU 82 uploads the program in the RAM and executes the corresponding instructions.

RAM 84 comprises, in a register, the program executed by the CPU 82 and uploaded after switch on of the device 80, input data in a register, intermediate data in different states of the method in a register, and other variables used for the execution of the method in a register.

The implementations described herein may be implemented in, for example, a method or a process, an apparatus, a software program, a data stream, or a signal. Even if only discussed in the context of a single form of implementation (for example, discussed only as a method or a device), the implementation of features discussed may also be implemented in other forms (for example a program). An apparatus may be implemented in, for example, appropriate hardware, software, and firmware. The methods may be implemented in, for example, an apparatus such as, for example, a processor, which refers to processing devices in general, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as, for example, computers, cell phones, portable/personal digital assistants ("PDAs"), and other devices that facilitate communication of information between end-users. Implementations of the various processes and features described herein may be embodied in a variety of different equipment or applications, particularly, for example, equipment or applications. Examples of such equipment include an encoder, a decoder, a post-processor processing output from a decoder, a pre-processor providing input to an encoder, a video coder, a video decoder, a video codec, a web server, a set-top box, a laptop, a personal computer, a cell phone, a PDA, a TV set and other communication devices. As should be clear, the equipment may be mobile and even installed in a mobile vehicle.

Additionally, the methods may be implemented by instructions being performed by a processor, and such instructions (and/or data values produced by an implementation) may be stored on a processor-readable medium such as, for example, an integrated circuit, a software carrier or other storage device such as, for example, a hard disk, a compact diskette ("CD"), an optical disc (such as, for example, a DVD, often referred to as a digital versatile disc or a digital video disc), a random access memory ("RAM"), or a read-only memory ("ROM"). The instructions may form an application program tangibly embodied on a processor-readable medium. Instructions may be, for example, in hardware, firmware, software, or a combination. Instructions may be found in, for example, an operating system, a separate application, or a combination of the two. A processor may be characterized, therefore, as, for example, both a device configured to carry out a process and a device that includes a processor-readable medium (such as a storage device) having instructions for carrying out a process. Further, a processor-readable medium may store, in addition to or in lieu of instructions, data values produced by an implementation.

As will be evident to one of skill in the art, implementations may produce a variety of signals formatted to carry information that may be, for example, stored or transmitted. The information may include, for example, instructions for performing a method, or data produced by one of the described implementations. For example, a signal may be formatted to carry as data the rules for writing or reading the syntax of a described embodiment, or to carry as data the actual syntax-values written by a described embodiment. Such a signal may be formatted, for example, as an electromagnetic wave (for example, using a radio frequency portion of spectrum) or as a baseband signal. The formatting may include, for example, encoding a data stream and modulating a carrier with the encoded data stream. The information that the signal carries may be, for example, analog or digital information. The signal may be transmitted over a variety of different wired or wireless links, as is known. The signal may be stored on a processor-readable medium.

A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, elements of different implementations may be combined, supplemented, modified, or removed to produce other implementations. Additionally, one of ordinary skill will understand that other structures and processes may be substituted for those disclosed and the resulting implementations will perform at least substantially the same function(s), in at least substantially the same way(s), to achieve at least substantially the same result(s) as the implementations disclosed. Accordingly, these and other implementations are contemplated by this application.