WO2009089091A2

WO2009089091A2 - Testing of color output of display devices

Info

Publication number: WO2009089091A2
Application number: PCT/US2009/030015
Authority: WO
Inventors: Dirk Andreas Vahlsing; Rashmin Desai
Original assignee: Silicon Image, Inc.
Priority date: 2008-01-04
Filing date: 2009-01-02
Publication date: 2009-07-16
Also published as: WO2009089091A3

Abstract

A system and method for testing of color output of display devices. A method for testing of a display device may include providing a series of inputs to the display device, the series of inputs representing all or a subset of the possible inputs to the display device. The method may further include measuring an output luminance from the display device for each of the series of inputs, and determining a quality of the display device based on the series of inputs and the output luminance measurements.

Description

TESTING OF COLOR OUTPUT OF DISPLAY DEVICES

RELATED APPLICATIONS

[0001] This application is related to and claims priority to U.S. provisional patent application 61/019,210, filed January 4, 2008.

TECHNICAL FIELD

[0002] Embodiments of the invention generally relate to the field of testing of electronic devices and, more particularly, to a method and apparatus for testing of the color output of display devices.

BACKGROUND

[0003] Television and other displays continue to improve in display quality to provide a better viewing experience. In addition to improvements in display definition and similar elements, television displays have improved in the numbers of colors that may be displayed.

[0004] The number of colors that may be displayed is commonly expressed by the number of bits of gradation available. This may be expressed either as bits per primary color (such as 8 bits per primary color), or as a total number of bits (24 bits if there are 8 bits for each of three primary colors. "Deep color" refers to extended resolution for digital video data beyond 8 bits per primary color. For most consumer digital video applications (including high-end consumer and low to mid-end professional), 8 bits of resolution for video data has been the maximum supported color resolution, while high-end professional applications, such as digital intermediates of cinematic films, have utilized 10-bits.

[0005] Considering the RGB (Red-Green-Blue) color space as one example, 8 bits for each of the three primary colors (also referred to as 24-bit color) results in a theoretical possibility of approximately 16.77 million colors that can be represented with 24 bits of RGB data. For simplicity, it is assumed that 0 represents a minimum brightness level (which may be referred to as "black"), and 255 represents a maximum brightness level (which may be referred to as "white"). To simplify this disclosure, minimum and maximum brightness levels are referred to herein as "black" and "white" respectively regardless of the colors actually represented at these brightness levels. The actual color represented by "white" and "black" will vary according to the display monitor, color scheme, current conditions, and other factors. For a horizontal, linear black to white ramp video signal, all three primary colors would step from 0 to 255 in unison, producing 256 shades of gray (including black and white). If a display is capable of producing 256 discrete brightness levels for each of the three primary colors, then the display is truly capable of representing 24- bit color resolution.

[0006] However, increased color resolution is being implemented in products, including consumer entertainment products. For example, HDMI™ (High- Definition Media Interface) version 1.3 protocol supports deep color. (HDMI is a trademark of HDMI Licensing, LLC) High-Definition Multimedia Specification 1.3 (Hitachi, Ltd., Matsushita Electric Industrial Co., Ltd., Philips Consumer Electronics, International B.V., Silicon Image, Inc., Sony Corporation, Thomson Inc., and Toshiba Corporation) (June 22, 2006). While HDMI is an example of a protocol that supports deep color, the principle of deep color or similar concepts is not limited to HDMI, and may be supported by other existing or future digital or analog video standards. Increasing the resolution of video data to 10, 12, or 16 bits results in an exponential increase in the number of discrete brightness levels, and therefore the total number of colors rises into billions of colors. However, this assumes that a display screen providing deep color is capable of producing the levels of intensity signified by the number of bits available. Certain display screens that are intended for deep color display may not be capable of actually providing all the available levels of intensity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements.

[0008] Figure 1 is an illustration of an embodiment of a testing system;

[0009] Figure 2 is an illustration of an embodiment of a system for providing display device testing;

[0010] Figure 3 is an illustration of an embodiment of a testing sequence for a display device;

[0011] Figure 4 is a flowchart to illustrate an embodiment of a testing process for a display;

[0012] Figure 5 is a flowchart illustrating test processes for a device under test; and

[0013] Figure 6 is an illustration of an embodiment of a computing device that may be included in an embodiment of the invention.

SUMMARY

[0014] Embodiments of the invention are generally directed to testing of color output of display devices. [0015] In a first aspect of the invention, an embodiment of a method for testing of a display device may include providing a series of inputs to the display device, the series of inputs representing all or a subset of the possible inputs to the display device. The method may further include measuring an output luminance from the display device for each of the series of inputs, and determining a quality of the display device based on the series of inputs and the output luminance measurements.

[0016] In a second aspect of the invention, a testing system for a display device may include a connection to the display device, the display device being a device under test, one or more sensors to detect luminance of the display device, and a sensor control to control the one or more sensors. The system may further include a test image generator, the test image generator to generate a series of inputs to the display device representing all or a subset of the possible inputs to the display device. The sensors measure an output luminance from the display device for each of the series of inputs, and the testing system calculates a quality of the display device based on the series of inputs and the output luminance measurements.

DETAILED DESCRIPTION

[0017] Embodiments of the invention are generally directed to testing of color output of display devices.

[0018] As used herein:

[0019] "Display device" means any type of video display, including television screens and computer monitors. The term display screen includes any display technology, including, but not limited to, LCD (liquid crystal display), plasma, CRT (cathode ray tube), and projection systems based on these technologies or others, including DLP/DMD (Digital Light Processing / Digital Mirror Device) technologies.

[0020] "Deep color" means color having greater than 8 bits of color depth per color component.

[0021] In some embodiments, a system provides for testing of color output of display devices. In some embodiments, a testing system provides for dividing a display under test into multiple sectors, and testing each sector. In some embodiments, testing includes stepping each sector through all or some portion of the possible color intensity values and measuring the color output at each tested value. In some embodiments, testing of a display device includes comparing the difference in luminance produced by a one- step input change to a nominal output luminance step. In other embodiments, testing of a display device includes counting different measured luminance levels and comparing this number to an expected number.

[0022] In some embodiments, a testing process includes calibrating the testing of a display to lower and upper calibration values, such limits producing "black" and "white" outputs (darker and brighter outputs), after every n steps to allow for drift in output values.

[0023] In some embodiments, a testing process maintains a stable total or average luminance for the display device under test, or for certain parts of the display, to prevent changes in backlight brightness or aperture that may occur in a display device when an image is lightened or darkened.

[0024] In an embodiment, testing of a display device includes testing of deep color capability. Deep color provides a display with greater color accuracy and vividness. Deep color assists in eliminating the occurrence of on-screen color banding, enabling tonal transitions that are very smooth, and allowing graduations of colors that are very subtle. Deep color further allows for increase in contrast ratio, and can represent many times more shades of gray between black and white. Deep color also minimizes "posturization", which refers to the effect that occurs when limited shades of gray or a small number of colors are used to display an image.

[0025] In an embodiment, a test process and system may be utilized to ensure that devices claiming to support deep color up to a certain color depths actually provide the promised color depths to the consumers' eyes. To meet the color depth requirements, a deep color capable display device must be capable of emitting (within a certain standard) as many luminance intensity levels as the supported color depth allows. The luminance levels should be well distributed throughout the whole luminance range. However, the requirement is not a requirement for absolute accuracy (in comparison with a theoretical black or white output, for example), but rather only a requirement for relative accuracy. In an embodiment, testing may concentrate on luminance output only, and not, for example, the particular colors displayed. In other embodiments, other factors, including the actual correctness of colors displayed by a display device, may be included in a testing process.

[0026] Test Approach - In some embodiments, testing of an output of a display screen includes the testing of color resolution by measuring the luminance provided by the display while the display is provided an input of a series of known input values. In an embodiment, a testing process is applied to deep color. However, embodiments of the invention are not limited to any particular color scheme. In an embodiment, a quality of the display device may be determined or calculated based on the input values and output luminance of the display device.

[0027] In some embodiments, a testing process includes the division of a display screen under test into a number of sectors. In one possible example, the screen is divided into nine sectors in a three-by-three grid, but an embodiment may utilize any number, size, and shape of sectors in any physical arrangement. For example, the sectors may be of unequal size, and different numbers of sectors may exist in different rows. In another example, the sectors may not line up in rows or columns, or may be of non-rectangular shape. In an embodiment, each of the sectors of the display device under test is tested separately. All of the sectors may be tested at the same time, but this is not required in all embodiments. A display device may vary in color resolution from one sector to another and thus the results from each sector of the display device may not be the same.

[0028] In an embodiment, a process provides for stimulating a display device, including, but not limited to, a deep color capable device, at its input with all possible intensity levels or some portion or subset of the possible intensity levels, and for measuring the emitted luminance level for each digital input level. If the display device under test supports the color depth that is used for stimulation, then any 1 LSB (least significant bit) step at the input should lead to a step of output luminance that also reflects 1 LSB of difference. The expected step of output luminance may be adjusted or modified if the display device includes a Gamma adjustment, as discussed below.

[0029] In some embodiments, a subset or subsets of the possible intensity levels may be utilized in stimulating a display device. For example, a subset may be chosen to represent continuous parts of the whole value range, such as [0...30], [60...70], [100...110],..., [220...255]. In this manner, only partial response curves will be produced, but each such curve can be analyzed. In an example, to save measurement time for a large set of values, such as in 16-bit deep color, a process may include conducting a pre-analysis using a subset of values. The resulting output may be used to identify critical parts of the display's response curve, and the process may then concentrate on these critical parts in a second, 16-bit measurement.

[0030] In some embodiment, a testing process for a display device or each sector of a display device involves stepping the display device or sector through each available digital value (for example example, up to 1024 values for each available step in 10-bit deep color in a grey scale mode), and evaluating the luminance level that is provided for each step. However, not all theoretically possible values may apply in each case. Depending on the video mode of a display, and the related color space for the display, it is possible that not all possible levels are valid or used for a particular display. For example, 8-bit RGB provided on computer monitors will generally use all 256 possible levels, 0 to 255. However, an 8-bit YUV signal only uses 224 levels from level 16 to 240. (YUV is a standard worldwide television color encoding system, in which Y = luma or brightness, U = blue minus luma, and V = red minus luma.) For deep color with 10-bit values, these values scale up by a factor of 4 to levels 64 to 960 being utilized in 10-bit YUV. As a result, there are 896 specified levels existing for 10-bit YUV, in comparison with 1024 for 10-bit computer RGB. In another possible example, xvYUV (xvYCC) uses all possible levels, in a similar manner as computer RGB.

[0031] However, certain display screens require the use of a well known process called "Gamma correction", which was originally used in older analog televisions. In this process, a non-linear input is provided to an output transfer function, which is the "gamma curve". In an embodiment, each measured luminance value may accordingly be corrected or adjusted to address the effect of the gamma curve. In implementation, modern digital televisions often "enhance" the image quality by using a gamma curve that, at least in part, doesn't follow the historic exponential curve used in gamma correction. In some embodiments, an algorithm is implemented to make educated guesses regarding how the appropriate gamma curve is split into segments, and what corrections (linear, exponential, or other corrections) need to be applied to each identified segment of a curve in order to reproduce a reasonably linear response curve. The corrected output can then in turn be rated by the testing algorithms.

[0032] It is understood that a system may be unable to provide a separate luminance level for every input. In some embodiments, a standard is applied to designate sufficient performance for a display device under test. In an embodiment, a calculation is made of the difference between the luminance for two measurements where the input level differs by 1 LSB (Least Significant Bit). In this manner, the difference between luminance levels represents an actual output step size for one input step. In an embodiment, it is also possible to calculate an expected or nominal output step size as:

S = (WL - BL)/N [1]

Where:

S = Nominal Output Step

WL = White Level Luminance

BL = Black Level Luminance

N = Number of steps the color space supports

[0033] In this manner, it is possible to express each observed output step size as a percentage of the nominal step size. In some embodiments, a standard is applied based on a comparison between the actual step size and the nominal step size. In an embodiment, a standard is applied requiring that the size of certain percentage of the actual measured output steps (for example, 80% of the measured output steps) is within a certain percentage of the nominal step size (such as +/- 20% of the nominal step size).

[0034] In another embodiment, a standard may be applied comparing the number of actual luminance levels to the number of input values. For example, if there are 1024 input levels, there potentially are 1024 separate monotonically increasing output levels, each such level being larger than the previous level. In an embodiment, a standard may be applied based on a comparison between the number of actual luminance levels and the number of potential luminance levels. In an embodiment, the number of actual luminance levels is required to be a certain percentage (for example, 80 to 90 %) of the number of potential luminance levels.

[0035] In some embodiments, the testing process of a display device will be implemented in grayscale, which may, for example, be implemented in steps from black to white (or white to black). In a particular example of an RGB display, the red, blue, and green components each would have the same intensity for incremental step to provide the steps from black to white. However, embodiments of the invention are not limited to this step process. In other embodiments, it is possible to step each color (such as red, green, and blue in an RGB display) or color pairs (for example, RG, RB, GB) through each level from dark to light as well. Color pairs may be utilized in, for example, DLP/DMD (Digital Light Processing/Digital Mirror Device) style rear projection televisions or projectors. Embodiments are not limited to any particular system. In addition to the RGB color space, an embodiment may be used for other color spaces, such as YUV, as well. Embodiments of the invention are not limited to any particular starting or ending point in steps, and are not limited to any particular stepping process. While the discussion here may be directed to stepping up intensity from black to white, a process can start at any of the steps, and may be reversed such that intensity is reduced with each step, down from white to black.

[0036] Calibration of Display Luminance Measurements to Address Drift - In some embodiments, a process is provided for calibrating the measurement of the luminance of a display device to account for drift in the luminance of a display over time due to various factors relating to the display itself or the outside environment. Display devices can drift quickly even over short time periods, and thus can affect the measurements made during a test of a display device. In an embodiment, because the measurement of luminance provides an absolute luminance level and the issue in testing is the relative luminance level of each step, the actual luminance measurements need to be recalibrated to known levels over time.

[0037] In some embodiments, a calibration process operates by utilizing extreme luminance values to provide for a basis for comparing other values. In an embodiment, the process includes measuring the luminance of a "black" value (which may be '0' in a 10-bit color system) and the luminance of a "white" value (which may be '1023' in a 10-bit color system), with white and black being measured in either order, to establish a first calibration, and then stepping through the measurement of a certain number of luminance LSB values. The calibration process then proceeds with another calibration of black and white measures after the certain number of measurement steps. The terms "black" and "white" may be used herein for convenience, but such the calibration values may vary in different embodiments. In some embodiments, the lower and upper calibration values may be the extreme valid minimum and maximum input levels a display can accept being used for calibration purposes. In other embodiments, other values may be used for calibration. For example, local minimum and maximum values of a small series of input values may be used for calibration, such as, for example, a value of 30 as "black", a value of 40 as "white", and the values 31 through 39 as the stimulus range utilized while measuring. In other instances, two suitably spaced levels from inside the stimulus range may be used. To simplify description, the terms "black" and "white" are used in this application to refer to the lower and upper calibration levels, and the mechanisms herein may be shown in terms of "black" and "white" valid input levels. Embodiments of the invention may use any number of measurement steps between calibrations. In one particular example, a calibration process will include measurement of black and white values, and then a series of seven measurement steps, thus providing a repeating nine-step process.

[0038] In some embodiments, through the use of black and white luminance measurements before and after a series of luminance steps, it is possible to interpolate what the luminance values for black and white were at the time each measurement is made. This may also be looked at mathematically as an offset value (the interpolated black level) and a full scale value (the interpolated white level to interpolated black level difference) that are generated for each measurement and then used to normalize the associated measured luminance value to a virtual black level of 0 and a virtual white level of 1 (which may be referred to as 100%, 2^ColorDepth-l or N valid levels, or whatever other mathematical form is suitable for further processing and/or the color space being used for stimulation).

[0039] In some embodiments, the calibrations then can be used to generate an expected luminance value for each step based on the relative black and white values. For example if for a particular step Z the calibrated black value is X and the calibrated white value is Y, and the system provides 10 bit deep color, or 1024 steps, then there should be 1024 luminance steps between X and Y (assuming that all steps are available). The expected luminance at Z to be Z steps between X and Y, within some threshold, such as plus or minus 20%.

[0040] Dynamic Backlight/Aperture Control - In some embodiments, a system provides for the testing of the luminance of a display device without being affected by backlight adjustments (or aperture control) of the display device. Because modern, non CRT/Plasma televisions generally will adjust the light input to the display's filter (e.g. LCD or DMD) in accordance with the overall brightness of a particular frame (reducing output for a dark image frame, increasing for a bright image frame), it is necessary to address this so that the testing of the display is not affected by lighting changes.

[0041] In some embodiments, a testing process includes providing a test pattern that maintains a relatively constant, or average, light output for the entire screen or any relevant part of the screen at any time. The test pattern may be designed so that the total brightness of the screen or relevant portion of the screen remains relatively constant (such as within a certain predetermined amount of variation) during the testing process. This process may be implemented whether or not the screen is split into multiple sectors for testing. The maintenance of a stable total luminance may then prevent the display under test from adjusting the backlight/aperture control based on frame brightness because the overall brightness of the display is unchanged for each test step.

[0042] Conventional television technology with regard to aperture control utilizes the luminosity of the whole display screen to determine if the luminosity of the television set or monitor should be modified. However, television sets may utilize the luminosity of a certain area of a display for purposes of aperture or backlight control for that area. In some embodiments, the luminosity of any such relevant area of the display screen remains constant during the testing process.

[0043] In some embodiments, the steps used in the testing and calibration of a display device may be used to assist in maintaining a relatively constant overall screen luminosity. In one example in which a display screen or relevant portion of the display screen is divided into a certain number of sectors (such as nine sectors) and the calibration and testing sequence is a repeating pattern of black, white, and then seven testing steps, then these steps can be staggered through the sectors to ensure equal luminance for the entire screen. At any point in time, there can be one sector that is black, one that is white, and seven sectors that have various levels of gray, with the total luminance provided by all the sectors remaining constant. In some embodiments, a system may have each sector stepping through the measurement levels starting at a different point (such as perhaps dividing the total steps into divisions and starting sectors at different divisions). In some embodiments, the measurements of certain sectors may be counting up in LSBs, while other sectors are counting down to offset each other. Embodiments of the invention are not limited to these processes, but may include any balancing processes to maintain the total luminance of the display device or portion of the display device at or near a constant value.

[0044] In some embodiments, total or average luminance of a display device may be maintained at a stable level without regard to the division of the display into sectors for testing. In some embodiments, total or average luminance of a display is maintained as a constant within each sector of the display.

[0045] Figure 1 is an illustration of an embodiment of a testing system. In this illustration, a display device under test 102 is tested using a testing tool 104. While the testing tool 104 is shown here as a single device for simplicity, in various implementations the testing tool 104 many include multiple elements, or may be a part of a larger system. In an embodiment, the display device 102 is divided into a certain number of sectors, which are here illustrated as nine sectors, sector-0 106 through sector-8 122. Each sector is tested utilizing a sensor 124 to detect luminance output. In some embodiments, the sensors may be a part of the testing tool 104. The sensors may use any known process for measuring luminance. The data from the sensors 126 is provided to the testing tool 104, which produces the test signals 128 for the display device 102. In an embodiment, the test signals will provide an input to step each of the sectors through the full color intensity range for the color output.

[0046] Figure 2 is an illustration of an embodiment of a system for providing display device testing. Figure 2 provides one implementation of a test system 200, and embodiments of the invention are not limited to this particular system arrangement, and may be implemented in varying systems utilizing more or fewer components. In this illustration, the display device under test (DUT) 202 may be a deep color compatible device. The display device 202 may receive input data from a deep color test image generator 208, which provides, for example, HDMI data to the display device 202. The data provided may also be DVI (Digital Visual Interface), UDI (Unified Display Interface), DisplayPort, or any other suitable digital or analog video data. Sensors 210 sensing the output of each sector of the display device 202 are controlled by a deep color sensor control 206. The sensor control 206 provides data to a computer 204 for processing, and may receive synchronization signals from the test image generator 208.

[0047] The testing system 200 may be implemented in different forms. For example, the computer 204 may be implemented as a microprocessor unit within the test system, and perform the analysis internally. In another example, the computer 204, sensor control 206, and test image generator 208 may be combined, such as in a single testing unit that provides the functions of each of such components.

[0048] Figure 3 is an illustration of an embodiment of a testing sequence for a display device. In this illustration, the testing sequence 300 includes a calibration sequence 330, followed by a certain number of luminance measurements 332. This process would be followed by the next calibration sequence 334, etc. The calibration sequence includes a "black" value 302 (lower calibration value) and a "white" value 304 (upper calibration value). This is followed by a certain number of measures, which in this particular example would be seven output steps, shown as LSB k 306 (where k is a counter to represent the sets of measurements made by the testing system) through LSB k + 6. This would then be followed by the next calibration sequence 334, which is again a "black" value 320 followed by a "white" value 322. In an embodiment, the testing sequence would include using the prior calibration 330 together with the later calibration 334 to determine what luminance values should be expected in the measurements, or to calibrate and/or normalize the measured values.

[0049] Figure 4 is a flowchart to illustrate an embodiment of a testing process for a display. In the illustrated process, a device under test (a display) is connected to a testing system 402. In some embodiments, the screen is divided into sectors for separate testing, in some embodiments a separate sensor is installed or placed in position for each sector 404. In other embodiments, one or more sensors may be moved into position for the testing of more than one sector of the display. [0050] A testing pattern is established for the display, which may include a pattern for each sector of the display 406. The establishment of the testing pattern may include a determination of the input steps required to step the display through each required output level to allow measurement of the display at each level 408. Embodiments may further include balancing of the testing between sectors of the display in order to maintain the overall luminance of the display at a constant or near constant level 410. In addition, establishment of the testing pattern may include establishing a testing pattern that includes periodic calibration at low (black) and high (white) levels to address any drift in luminance 412.

[0051] Subsequent to the establishment of the testing pattern, the display is tested using the testing pattern 414. The test results then may be evaluated to determine or calculate the performance of the display, such as, for example, compliance with deep color requirements.

[0052] Figure 5 is a flowchart illustrating test processes for a device under test. In this illustration, a display device is connected with a testing system, with the display being divided into n sectors 502. Testing is to be performed for each sector of the display screen 504. In an embodiment, testing of the display screen includes balancing the testing so that the total luminance of the display remains relatively constant during the testing process 506. For each sector of the display 510, the testing process includes stepping through each available input to determine the output. For example, this may be illustrated by a variable k which begins as zero 512, with the testing including calibration using black and white values 514, followed by measurement of the output for a series of steps represented by steps (k + 0) through (k + m) 516. This is followed by the next calibration sequence 518. If there are still steps left to be measured 520, then the counter k is incremented (k = k + m + 1) 522 and the next series of measurements are made 516. When all steps have been measured, calibration and/or normalization of measured data may take place 524, and any Gamma component present in the measures may be removed 526 from all luminance outputs of all sectors. The luminance output for each of the sectors may then be evaluated to determine how well the display under test performed 528.

[0053] Figure 6 is an illustration of an embodiment of a computer system that may be included in an embodiment of the invention. In this illustration, certain standard and well known components that are not germane to the present description are not shown. Under some embodiments, a computing system 600 may include all or a part of a testing system for a display.

[0054] In some embodiments, the computing system 600 may include a display device 622. In some embodiments, the display device 622 may be a device under test. The computing system 600 may further include sensors to detect luminance of sectors of the display device 622. The sensors may be under control of a sensor control 626, and the display device may provide an output based on a test pattern generated by a test image generator 628. The display 622 may be a liquid crystal display (LCD), a plasma display, a cathode ray tube (CRT) display, projection system or any other display technology.

[0055] Under some embodiments, the computing system 600 comprises an interconnect or crossbar 602 or other communication means for communicating information, which may include high speed data transport. The computing system 600 further includes a processing means such as one or more processors 604 coupled with the interconnect 602 for processing information. The processors 604 may comprise one or more physical processors and one or more logical processors. Further, each of the processors 604 may include multiple processor cores. The interconnect 602 is illustrated as a single interconnect for simplicity, but may represent multiple different interconnects or buses and the component connections to such interconnects may vary. The interconnect 602 shown in Figure 6 is an abstraction that represents any one or more separate physical buses, point-to-point connections, or both connected by appropriate bridges, adapters, or controllers. The interconnect 602 may include, for example, a system bus, a PCI or PCIe bus, a HyperTransport or industry standard architecture (ISA) bus, a small computer system interface (SCSI) bus, a HC (I2C) bus, or an Institute of Electrical and Electronics Engineers (IEEE) standard 1394 bus, sometimes referred to as "Firewire". ("Standard for a High Performance Serial Bus" 1394-1995, IEEE, published August 30, 1996, and supplements) The computing device 600 further may include a serial bus, such as USB bus 616, to which may be attached one or more USB compatible devices, such as device A 618 and device B 620.

[0056] In some embodiments, the processors 604 may be utilized to support one or more virtual machines. In some embodiments, the computing system 600 further comprises a random access memory (RAM) or other dynamic storage device as a main memory 606 for storing information and instructions to be executed by the processors 604. Main memory 606 also may be used for storing temporary variables or other intermediate information during execution of instructions by the processors 604. RAM memory includes dynamic random access memory (DRAM), which requires refreshing of memory contents, and static random access memory (SRAM), which does not require refreshing contents, but at increased cost. DRAM memory may include synchronous dynamic random access memory (SDRAM), which includes a clock signal to control signals, and extended data-out dynamic random access memory (EDO DRAM). In some embodiments, memory of the system may include a shared memory, such as a shared BIOS/OS memory, that is accessible by multiple agents in the device. The computing system 600 also may comprise a read only memory (ROM) 612 or other static storage device for storing static information and instructions for the processors 604. The computing system 600 may include one or more non-volatile memory devices 614 for the storage of certain elements.

[0057] Data storage 608 may also be coupled to the interconnect 602 of the computing system 600 for storing information and instructions. The data storage 608 may include a magnetic disk, an optical disc and its corresponding drive, or other memory device. Such elements may be combined together or may be separate components, and utilize parts of other elements of the computing system 600. In a particular embodiment, the data storage 608 may include a hard drive 610.

[0058] An input device 630 may be coupled to the interconnect 602 for communicating information and/or command selections to, for example, the processors 604 or to the test image generator 628. In various implementations, the input device 630 may be a keyboard, a keypad, a touch-screen and stylus, a voice-activated system, or other input device, or combinations of such devices. Another type of user input device that may be included is a cursor control device 632, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to the one or more processors 604 or the test image generator 628.

[0059] One or more communication elements 634 may also be coupled to the interconnect 602. Depending upon the particular implementation, the communication elements 634 may include a transceiver, a wireless modem, a network interface card, LAN (Local Area Network) on motherboard, or other interface device. The communication elements 634 may provide a connection to a network 636 to transmit network data, such as Ethernet data. The uses of a communication device 634 may include reception of signals from wireless devices. For radio communications, the communication device 634 may include one or more antennas 640, including any dipole or monopole antennas, as required. In one embodiment, the communication elements 634 may include a firewall to protect the computing system 600 from improper access. The computing system 600 may also comprise a power device or system 642, which may comprise a power supply, a battery, a solar cell, a fuel cell, or other system or device for providing or generating power. The power provided by the power device or system 642 may be distributed as required to elements of the computing system 600.

[0060] In the description above, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form. There may be intermediate structure between illustrated components. The components described or illustrated herein may have additional inputs or outputs which are not illustrated or described.

[0061] Various embodiments of the present invention may include various processes. These processes may be performed by hardware components or may be embodied in computer program or machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor or logic circuits programmed with the instructions to perform the processes. Alternatively, the processes may be performed by a combination of hardware and software. [0062] Portions of various embodiments of the present invention may be provided as a computer program product, which may include a computer-readable medium having stored thereon computer program instructions, which may be used to program a computer (or other electronic devices) to perform a process according to the embodiments of the present invention. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, compact disk read-only memory (CD-ROM), and magneto-optical disks, read-only memory (ROM), random access memory (RAM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), magnet or optical cards, flash memory, or other type of media/machine-readable medium suitable for storing electronic instructions for execution by a processor. Moreover, the present invention may also be downloaded as a computer program product, wherein the program may be transferred from a remote computer to a requesting computer.

[0063] Many of the methods are described in their most basic form, but processes can be added to or deleted from any of the methods and information can be added or subtracted from any of the described messages without departing from the basic scope of the present invention. It will be apparent to those skilled in the art that many further modifications and adaptations can be made. The particular embodiments are not provided to limit the invention but to illustrate it. The scope of the embodiments of the present invention is not to be determined by the specific examples provided above but only by the claims below.

[0064] If it is said that an element "A" is coupled to or with element "B," element A may be directly coupled to element B or be indirectly coupled through, for example, element C. When the specification or claims state that a component, feature, structure, process, or characteristic A "causes" a component, feature, structure, process, or characteristic B, it means that "A" is at least a partial cause of "B" but that there may also be at least one other component, feature, structure, process, or characteristic that assists in causing "B." If the specification indicates that a component, feature, structure, process, or characteristic "may", "might", or "could" be included, that particular component, feature, structure, process, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, this does not mean there is only one of the described elements.

[0065] An embodiment is an implementation or example of the present invention. Reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. It should be appreciated that in the foregoing description of exemplary embodiments of the present invention, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims are hereby expressly incorporated into this description, with each claim standing on its own as a separate embodiment of this invention.

Claims

CLAIMSWhat is claimed is:

1. A method for testing a display device comprising: providing a series of inputs to the display device, the series of inputs representing all or a subset of the possible inputs to the display device; measuring an output luminance from the display device for each element of the series of inputs; and determining a quality of the display device based on the series of inputs and the output luminance measurements.

2. The method of claim 1, further comprising dividing the display screen into a plurality of sectors, and further comprising testing each of the plurality of sectors of the display device.

3. The method of claim 1, further comprising adjusting the output luminance measurements to remove a Gamma correction.

4. The method of claim 1, wherein the display device utilizes a plurality of colors, and wherein the series of inputs provide for the same intensity for each of the plurality of colors.

5. The method of claim 1, wherein the display device utilizes a plurality of colors, and wherein each of the plurality of colors is tested separately.

6. The method of claim 1, wherein the display device utilizes a plurality of colors, and wherein the series of inputs provide for the same intensity for groups of the plurality of colors.

7. A method for calibrating a measurement of an output luminance of display device comprising: performing a first calibration measurement including performing a first measurement of a lower brightness level resulting from a first input to the display device and a first measurement of an upper brightness level resulting from a second input to the display device; measuring a series of output luminance values resulting from a series of inputs to the display device; performing a second calibration measurement including performing a second measurement of the lower brightness level resulting from the first input to the display device and a second measurement of the upper brightness level resulting from the second input to the display device; and calibrating the output luminance measurements based on the first calibration measurement and the second calibration measurement.

8. The method of claim 7, wherein calibrating the output luminance measurements includes interpolating a current lower brightness level and a current upper brightness level of the display device for each of the series of output luminance measurements.

9. The method of claim 8, wherein calibrating the output luminance measurements includes generating an expected luminance for each input to the display device based on the current lower brightness level and the current upper brightness level of the display device.

10. A method of testing a display device comprising: determining a test pattern for the display device, the test pattern including a first group of one or more inputs and a second group of one or more inputs; inputting the first group of one or more inputs to the display device; measuring a first group of one or more outputs of the display device resulting from the first group of inputs; inputting the second group of one or more inputs to the display device; and measuring a second group of one or more outputs of the display device resulting from the first group of inputs; wherein the first group of outputs and the second group of outputs provide a stable luminance for all or a part of the display device.

11. The method of claim 10, wherein all or the part of the display device is divided into a plurality of sectors for testing, and wherein the output of the sectors are balanced to provide the stable luminance for all or the part of the display device.

12. The method of claim 11, wherein the stable luminance for the display device is utilized to avoid changes in an aperture control or backlight of the display device during testing of the display device.

13. The method of claim 11, wherein the stable luminance for each of the sectors of the display device is utilized to avoid changes in an aperture control or backlight of each of the sectors of the display device during testing of the display device.

14. A testing system for a display device comprising: a connection to the display device, the display device being a device under test; one or more sensors to detect luminance of the display device; a sensor control to control the one or more sensors; and a test image generator, the test image generator to generate a series of inputs to the display device, the series of inputs representing all or a subset of the possible inputs to the display device; wherein the sensors measure an output luminance from the display device for each of the series of inputs; and wherein the testing system calculates a quality of the display device based on the series of inputs and the output luminance measurements.

15. The system of claim 14, wherein each sensor senses the luminance of a sector of the display device.

16. The system of claim 14, wherein the system is to adjust the output luminance measurements to remove a Gamma correction.

17. The system of claim 14, wherein the series of inputs generated by the test image generator is to provide for a calibration of the measurements, the calibration of the measures to include: performing a first calibration measurement including performing a first measurement of a lower brightness level resulting from a first input to the display device and a first measurement of an upper brightness level resulting from a second input to the display device; measuring a series of output luminance values resulting from a series of inputs to the display device; performing a second calibration measurement including performing a second measurement of the lower brightness level resulting from the first input to the display device and a second measurement of the upper brightness level resulting from the second input to the display device; and calibrating the output luminance measurements based on the first calibration measurement and the second calibration measurement.

18. The system of claim 14, wherein the series of inputs generated by the test image generator is to provide for a stable luminance of the display device, the generation of the series of inputs to include: determining a test pattern for the display device, the test pattern including a first group of one or more inputs and a second group of one or more inputs; inputting the first group of one or more inputs to the display device; measuring a first group of one or more outputs of the display device resulting from the first group of inputs; inputting the second group of one or more inputs to the display device; and measuring a second group of one or more outputs of the display device resulting from the first group of inputs; wherein the first group of outputs and the second group of outputs provide a stable luminance for the display device.