Dynamic range test chart for devices with a reflective lens

Abstract

Test charts for testing the dynamic range of mobile phone cameras. One example dynamic range test chart includes test patches, each patch having a brightness value, and alignment features arranged in the corners of the test chart. The test patches include an outer plurality of test patches annularly arranged on a first side of the test chart, and an inner plurality of test patches annularly arranged on a second side of the test chart. A brightness value of a darkest test patch included in the outer plurality of test patches is the same as a brightness value of a brightest test patch included in the inner plurality of test patches. The test patches are positioned such that light from test patches that is reflected off a flat cover element of a camera-under-test lands on portions of the test chart outside the test patches.

Description

DYNAMIC RANGE TEST CHART FOR DEVICES WITH A REFLECTIVE LENSBACKGROUND1. Cross-Reference to Related Applications

[0001] This application claims the benefit of priority from PCT Application No. PCT / CN2023 / 111787, filed on 8 August 2023, U.S. Provisional Application No. 63 / 592,674, filed on 24 October 2023, and European Application No. 23208408.7 filed on 7 November 2023, each of which is incorporated by reference herein in its entirety.2. Field of the Disclosure

[0002] This application relates generally to test charts and, particularly, to a dynamic range test chart for devices having reflective lenses.3. Description of Related Art

[0003] Testing of dynamic range of cameras includes taking a picture of a test chart. Test charts include a plurality of square patches arranged in an order of bright patches to dark patches. High precision and high density test charts may be formed on photographic film or chrome on glass.BRIEF SUMMARY OF THE DISCLOSURE

[0004] Dynamic range test charts are testing instruments (e.g., testing devices, testing tools) that are used to identify the dynamic range of image capturing devices, such as cameras.Particularly, test charts include a plurality of test patches (for example, individual squares having a constant tone) that vary in brightness from one patch to another. The brightness value (or tone value) of each patch is known. When a camera takes a picture of the test chart in a controlled environment, the captured brightness values are processed to identify the dynamic range of the camera. However, modern phone cameras include a piece of glass that is flat and uncoated, resulting in reflections within captured images. When taking a picture of a dynamic range test chart, these reflections cause dark portions of the test chart to appear brighter than reality, resulting in an inaccurate test of the dynamic range of the phone camera.

[0005] To overcome such issues, embodiments described herein provide a test chart having patches arranged in a substantially circular pattern. Patches on the test chart are situated on a side opposite of expected light reflections to avoid reflections impacting measured brightness values of the patches when captured by the camera. Additionally, brighter patches are situated away from darker patches to avoid light interference. The organization and ordering of test chartpatches described herein avoid light reflection and vignetting issues experienced by traditional test charts when captured by a phone camera.

[0006] Various aspects of the present disclosure relate to test charts for testing the dynamic range of cameras. One example embodiment provides a dynamic range test chart, the test chart including a plurality of test patches, each patch having a brightness value, and a plurality of alignment features arranged in the corners of the test chart. The plurality of test patches include an outer plurality of test patches annularly arranged on a first side of the test chart, and an inner plurality of test patches annularly arranged on a second side of the test chart. A brightness value of a darkest patch included in the outer plurality of test patches is the same as a brightness value of a brightest patch included in the inner plurality of test patches. The test chart has a center, and the test chart does not have any test patches at locations that are the same distance from the center, but rotated 180°, from another test patch in the plurality of test patches.

[0007] According to another example embodiment, provided is a dynamic range test chart, the test chart including a plurality of test patches annularly arranged on the test chart, each patch having a brightness value. The plurality of test patches includes a first brightest patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest patch of the plurality of test patches. When moving clockwise around the plurality of test patches, brightness values of subsequent patches decrease from the first brightest patch to the darkest patch. The test patches are positioned such that light from test patches that is reflected off a flat lens element of a camera-under-test lands on portions of the test chart that is outside the plurality of test patches.

[0008] According to another example embodiment, provided is a dynamic range testing system comprising a dark box housing configured to absorb light, a testing device within the dark box housing, the testing device including a camera, a light source configured to project light to the testing device, and a test chart situated between the light source and the testing device. The test chart includes a plurality of test patches annularly arranged on the test chart, each patch having a brightness value. The plurality of test patches includes a first brightest patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest patch of the plurality of test patches. When moving clockwise around the plurality of test patches, brightness values of subsequent patches decrease from the first brightest patch to the darkest patch. The test patches are positioned such that light from test patches that is reflected off a flat lens element of the camera lands on portions of the test chart outside the plurality of test patches.

[0009] According to another example embodiment, provided is a dynamic range test chart comprising a center and a plurality of test patches, each test patch having a brightness value. The test chart does not have any test patches at locations that are the same distance from the center, but rotated 180°, from another test patch in the plurality of test patches.

[0010] According to another example embodiment, provided is a dynamic range test chart including a plurality of test patches, each test patch having a brightness value. The test patches are positioned such that light from test patches that is reflected off a flat lens element of a camera-under-test lands outside the plurality of test patches.

[0011] In this manner, various aspects of the present disclosure provide for accurate dynamic range testing of devices having a reflective lens, and effect improvements in at least the technical fields of image projection, imaging capturing, video recording, and the like.DESCRIPTION OF THE DRAWINGS

[0012] These and other more detailed and specific features of various embodiments are more fully disclosed in the following description, reference being had to the accompanying drawings, in which:

[0013] FIG. 1 illustrates an imaging system illustrating light beams captured by a phone camera according to aspects of the present disclosure;

[0014] FIG. 2 illustrates a test chart according to aspects of the present disclosure;

[0015] FIGS. 3A-3B illustrates the test chart of FIG. 2 including light reflections according to aspects of the present disclosure;

[0016] FIG. 4 illustrates a dark box for capturing the test chart of FIG. 2 according to aspects of the present disclosure; and

[0017] FIG. 5 illustrates a dynamic range test result according to aspects of the present disclosure.DETAILED DESCRIPTION

[0018] In the following description, numerous details are set forth, such as optical device configurations, timings, operations, and the like, in order to provide an understanding of one or more aspects of the present disclosure. It will be readily apparent to one skilled in the art that these specific details are merely exemplary and not intended to limit the scope of this application.

[0019] Moreover, while the present disclosure focuses mainly on examples in which the various embodiments are used in testing mobile phone cameras, it will be understood that this is merely one example of an implementation. It will further be understood that the disclosed systems and methods can be used in any device in which there is a need to identify a dynamic range; for example, cinema, consumer, and other commercial projection systems, heads-up displays, virtual reality displays, and the like.

[0020] In embodiments described herein, “bright” and “dark” are used to refer to color tones of patches. Typically, “bright” refers to a patch that is “more white” and “dark” refers to a patch that is “more black.” Accordingly, a patch that is “brighter” is “more white” and a patch that is “darker” is “more black.”

[0021] FIG. 1 illustrates an example imaging system 100 including a test chart 102 captured by a mobile device camera (for example, a cell phone camera). When the test chart 102 is captured by the camera, the test chart 102 is mapped onto a complementary metal oxide semiconductor (CMOS) sensor 104 in the camera. The CMOS sensor 104 converts light into electrical signals that are used to recreate the captured image onto a screen.

[0022] For example, consider a patch 106, such as a bright spot on the test chart 102. When the image is captured, first light 108 travels from the patch area 106 through a cover element 110 and optical element 112 to the CMOS sensor 104. Many phone camera lenses include a cover element such as an uncoated flat (e.g., planar) piece of glass (or similar optical material such as clear plastic) over the camera to protect the camera. However, this uncoated cover element 110 may cause reflections, and thus acts as a mirror. The optical element 112 receives the first light 108 (that is, the portion of the light 108 that is not reflected by the cover element 110) and directs the light onto the CMOS sensor 104. While illustrated as a single lens, the optical element 112 may include a plurality of various lenses to direct and focus the first light 108 onto the CMOS sensor 104, such as concave lenses, convex lenses, biconcave lenses, biconvex lenses, planoconcave lenses, planoconvex lenses, negative meniscus lenses, positive meniscus lenses, and combinations thereof.

[0023] A first reflected light 114 is the portion of first light 108 reflected by the cover element 1 10 back towards the test chart 102 at an angle cp. The first reflected light 1 14 creates a reflected patch 116 on the test chart 102 at a location opposite the patch 106 with respect to a center point 115 of the test chart 102. The reflected patch 116 is also captured by the CMOS sensor 104. Particularly, when the image is captured, second light 118 travels from the reflected patch 116 through the cover element 110 and optical element 112 to the CMOS sensor 104. As the reflected patch 116 is not an intended feature of the test chart 102, the reflected patch 116 creates artifacts within the image captured by the CMOS sensor 104.

[0024] Typical test charts include, for example, the OECF-36 test chart and the Xy la-21 test chart. The OECF-36 test chart includes a plurality of test patches arranged in an array or matrix having bright patches at a top portion and dark patches at a bottom portion. However, when the OECF-36 test chart is captured by a phone camera having an uncoated cover element, reflections of the bright patches cause the dark patches to brighten. Accordingly, the dynamic range of the phone camera is not accurately identified. Similarly, the Xyla-21 test chart is arranged linearly having bright patches at a leftmost portion and dark patches at a rightmost portion. As occurs with the OECF-36 test chart, reflections of the bright patches cause the dark patches to brighten, and again the dynamic range of the phone camera is not accurately identified. Additionally, as the region of interest in the previous test charts is wide, lens vignetting may occur, further amplifying the artifacts caused by reflections. In some instances, neighboring patches are too close or have different brightness levels, and artifacts may cause interferences in neighboring patches.

[0025] Accordingly, a new test chart is desired to avoid reflections creating artifacts within dynamic range tests. Particularly, to avoid issues provided by test charts such as the OECF-36 and the Xyla-21 test charts, a test chart is desired that avoids situating patches in a central symmetry area where reflections impact image results. Additionally, to avoid interferences of neighbored patches and artifacts due to lens vignetting, test charts described herein provide patches arranged in a concentric pattern and aligned according to brightness level.

[0026] FIG. 2 provides a new test chart 200 according to embodiments described herein. The test chart 200 includes a plurality of test patches 202 arranged as an outer plurality of test patches 204 and an inner plurality of test patches 206 spaced apart by a distance x. As illustrated in FIG. 2, the plurality of test patches 202 are arranged in a substantially circular pattern. However, in some instances, the plurality of test patches 202 may instead be arranged in a substantially oval or other annular pattern. For the sake of clarity, only a subset of the plurality of test patches 202 are labelled (such as first patch 202A, second patch 202B, etc.).

[0027] The outer plurality of test patches 204 include a first patch 202A and a second patch 202B that are the brightest patches within the test chart 200. Beginning with the first patch 202A and moving counter-clockwise around the outer plurality of test patches 204, each patch of the outer plurality of test patches 204 reduces in brightness until a third patch 202C is reached. Similarly, beginning with the second patch 202B and moving clockwise around the outer plurality of test patches 204, each patch 202 of the outer plurality of test patches 204 reduces in brightness until the third patch 202C is reached. The outer plurality of test patches 204 form a semicircle within the test chart 200 and are substantially restrained by an axis 208 such that all patches 202 within the outer plurality of test patches 204 are situated on a first side of the axis 208. In some instances, the axis 208 is aligned with a center of the test chart 200 (for example, at a center patch 210). In other instances, the axis 208 is offset from the center of the test chart 200.

[0028] The inner plurality of test patches 206 include a fourth patch 202D. In some instances, a brightness value or tone of the fourth patch 202D is the same as the brightness value of the third patch 202C. By setting the third patch 202C and the fourth patch 202D to have the same tone, the third patch 202C and the fourth patch 202D can be treated as a check for vignetting. Beginning with the fourth patch 202D and moving counter-clockwise around the inner plurality of test patches 206, each patch 202 of the inner plurality of test patches 206 reduces in brightness until a fifth patch 202E is reached. The fifth patch 202E may be a fully black patch. Additionally, the inner plurality of test patches 206 includes a sixth patch 202F. The sixth patch 202F has a brightness value darker than the fourth patch 202D. Beginning with the sixth patch 202F and moving clockwise around the inner plurality of test patch 206, each patch 202 of the inner plurality of test patches 206 reduces in brightness until the fifth patch 202E is reached.

[0029] The inner plurality of test patches 206 form a semicircle within the test chart 200 and are substantially restrained by the axis 208 such that all patches 202 within the inner plurality of test patches 206 are situated on a second side of the axis 208. The second side of the axis 208 may be opposite the first side of the axis 208 such that the inner plurality of test patches 206 is on an opposite side of the axis 208 than the outer plurality of test patches 204. In some implementations, a patch 202 or a portion of a patch 202 included in the inner plurality of test patches 206 may be situated on the first side of the axis 208. As the outer plurality of test patches 204 and the inner plurality of test patches 206 are separated by the distance x, brighter patches are separated from darker patches, avoiding interference between brighter patches and darker patches. Additionally, the test chart 200 may have a fully black background to assist with avoiding interference between brighter patches and darker patches.

[0030] The test chart 200 also includes several features to assist with alignment of the CMOS sensor 104 with the test chart 200. For example, the test chat 200 includes center patch 210 and a plurality of alignment features 212 surrounding the center patch 210 (for example, first alignment feature 212A, second alignment feature 212B, third alignment feature 212C, and fourth alignment feature 212D). Additionally, the test chart 200 may include alignment patches 214 situated at one corner, multiple comers, or each corner of the test chart 200 for example, first alignment patch 214A, second alignment patch 214B, third alignment patch 214C, and fourth alignment patch 214D). In other implementations, the test chart 200 may include fewer or more alignment features 212 and alignment patches 214. In some instances, the alignment patches 214 are numbered to assist with manually choosing sequences for analysis of the test chart (an example of which is shown in FIG. 3 A). The alignment patches 214 may include two or more tones of color. For example, a brightest one of the tones is primarily referred to for alignment, while a darker one of the tones is primarily used for printing logos or numbers (as shown in FIG. 3A).

[0031] In the example of FIG. 2, each patch 202 of the plurality of test patches have a same size. However, in other implementations, the dimensions of the patches 202 may vary. For example, in one instance, brighter patches (such as first patch 202A and second patch 202B) may be smaller than dark patches (such as fourth patch 202D and sixth patch 202F). Additionally, in the example of FIG. 2, each patch 202 is a square. In other implementations, the patches 202 may be provided as other shapes, such as rectangles or circles.

[0032] In some instances, the test chart 200 is printed on film (for example, a multi-level film, a transparent film). In other instances, the test chart 200 is embedded in glass, printed on filters having different transparency or optical density, or the like. The brightness level of each of the plurality of test patches 202 is established based on an amount of ink applied to the respective portion of the film. In other instances, the test chart 200 is formed by providing sheets of chrome on glass.

[0033] FIGS. 3A-3B provide an image of a captured test chart 300 as captured (e.g., imaged) by a CMOS sensor 104. For example, the captured test chart 300 is the test chart 200 including reflections caused by the cover element 110 of FIG. 1. The captured test chart 300 includes the plurality of test patches 202 and additionally includes a plurality of reflected patches 302. For the sake of clarity, only a subset of the plurality of reflected patches 302 are labelled. As described, the patches 202 that form the outer plurality of test patches 204 are generally brighter than the patches 202 that form the inner plurality of test patches 206. Accordingly, the reflections of the patches 202 are brighter, and the plurality of reflected patches 302 are generallyviewed as part of the outer circle of patches 202 (e.g., aligned with the outer plurality of test patches 204). While FIGS. 3 A-3B illustrate reflected patches for the inner plurality of test patches 206, in some situations the reflected patches for the inner plurality of test patches 206 may be sufficiently dark to not be captured by the CMOS sensor 104 and not interfere with dynamic range measurements.

[0034] The plurality of reflected patches 302 are situated on an opposite side of the axis 208 than the plurality of test patches 202. The plurality of reflected patches 302 includes, among additional patches, a first reflected patch 302A that is a reflection of the first patch 202A, a second reflected patch 302B that is a reflection of the second patch 202B, and a third reflected patch 302C that is a reflection of the third patch 202C. As there are no patches in this region of the test chart 200, 300, the plurality of reflected patches 302 do not create artifacts in the captured image.

[0035] In the example of FIG. 3A, the test chart is aligned with the CMOS sensor 104 such that no artifacts are present in the captured image. However, the test chart may be misaligned with the CMOS sensor 104. For example, in FIG. 3B, the captured test chart 300 includes artifacts due to misalignment. As shown in FIG. 3B, when the test chart is misaligned with the cover element 110, a reflected center patch 312 interferes with the center patch 210 and alignment features 212. Additionally, reflected alignment patches 314 interfere with the alignment patches 214. For example, a first reflected alignment patch 314A interferes with the first alignment patch 214 A, a second reflected alignment patch 314B interferes with the second alignment patch 214B, a third reflected alignment patch 314C interferes with the third alignment patch 214C, and a fourth reflected alignment patch 314D interferes with the fourth alignment patch 214D. Accordingly, misalignment may be identified and corrected. Additionally, due to the arrangement of the plurality of test patches 202 in a semi-circular arrangement, minor misalignment along the positive x-axis may not interfere with testing of the dynamic range of the phone camera. However, misalignment along the negative x-axis may still cause the reflections to overlap with the test patches.

[0036] When capturing the test chart 200, any additional light present in the system may disrupt measurements by causing reflections on patches or otherwise by introducing additional flare (e.g., veiling glare) into the image. To avoid external light, a dark box (for example, a black box, a darkened room) may be used to create a dark space. FIG. 4 provides an example dynamic range testing system 400. The dynamic range testing system 400 includes a light source 402 (for example, a lightbox) configured to project light towards a test device 404. The test device 404 may be, for example, a mobile phone camera having a CMOS sensor 104 as described withrespect to FIG. 1. The test chart 200 is situated on the light source 402 such that the light projected by the light source 402 travels through the test chart 200 and to the test device 404. The dynamic range testing system 400 includes a dark box housing 406 configured to absorb light projected by the light source 402. Absorbing the light reduces or eliminates direct reflections being received by the test device 404. The dark box housing 406 may be covered by, for example, black paint, black felt, acktar black foil, vantablack, or the like to absorb the light.

[0037] FIG. 5 illustrates a chart 500 showing an example dynamic range test result of the test device 404. The chart 500 provides a luminance level of each test patch within the captured test chart 300 as captured by the test device 404. As shown, the image of the captured test chart 300 as captured by the test device 404 varies in luminance level over approximately 12 different test patches (e.g., from test patch 6 to test patch 18). Accordingly, the test device 404 has a dynamic range of approximately 12.

[0038] Systems, methods, and devices in accordance with the present disclosure may take any one or more of the following configurations.

[0039] (1) A dynamic range test chart, the test chart comprising: a plurality of test patches, each test patch having a brightness value, the plurality of test patches including: an outer plurality of test patches annularly arranged on a first side of the test chart, and an inner plurality of test patches annularly arrange on a second side of the test chart, wherein a brightness value of a darkest test patch included in the outer plurality of test patches is the same as a brightness value of a brightest test patch included in the inner plurality of test patches, wherein the test chart has a center, and wherein the test chart does not have any test patches at locations that are the same distance from the center, but rotated 180°, from another test patch in the plurality of test patches; and a plurality of alignment features arranged in the corners of the test chart.

[0040] (2) The test chart according to (1), wherein the first side of the test chart and the second side of the test chart are separated by an axis, and wherein the axis is misaligned with a center of the test chart.

[0041] (3) The test chart according to any one of (1 ) to (2), wherein the outer plurality of test patches includes a first bright test patch, and wherein, when moving clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the first bright test patch to the darkest test patch included in the outer plurality of test patches.

[0042] (4) The test chart according to (3), wherein the outer plurality of test patches further includes a second bright test patch situated at an opposite end of the outer plurality of testpatches than the first bright test patch, and wherein, when moving counter-clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the second bright test patch to the darkest test patch included in the outer plurality of test patches.

[0043] (5) The test chart according to any one of (1) to (4), wherein the inner plurality of test patches includes a full black test patch.

[0044] (6) The test chart according to any one of (1) to (5), wherein the test chart further comprises a center test patch situated at a center of the test chart and having a second plurality of alignment features.

[0045] (7) A dynamic range test chart, the test chart comprising: a plurality of test patches annularly arranged on the test chart, each test patch having a brightness value, the plurality of test patches including: a first brightest test patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest test patch of the plurality of test patches, wherein, when moving clockwise around the plurality of test patches, brightness values of subsequent test patches decrease from the first brightest test patch to the darkest test patch, wherein the test patches are positioned such that light from test patches that is reflected off a flat lens element of a camera-under-test lands on portions of the test chart that is outside the plurality of test patches.

[0046] (8) The test chart according to (7), wherein the plurality of test patches is an outer plurality of test patches arranged at a first distance from a center of the test chart, and wherein the test chart further includes an inner plurality of test patches arranged at a second distance from the center of the test chart, wherein the second distance is less than the first distance.

[0047] (9) The test chart according to (8), wherein a brightness value of the darkest test patch included in the outer plurality of test patches is the same as a brightness value of a brightest test patch included in the inner plurality of test patches.

[0048] (10) The test chart according to any one of (7) to (9), wherein the plurality of test patches are arranged on a first side of the test chart opposite a second side, wherein the first side of the test chart and the second side of the test chart are separated by an axis misaligned with a center of the test chart.

[0049] (11) The test chart according to any one of (7) to (10), wherein the plurality of test patches further includes: a second bright test patch situated at a second end of the outer plurality of test patches, and wherein, when moving counter-clockwise around the outer plurality of testpatches, rightness values of subsequent test patches decrease from the second bright test patch to the darkest test patch.

[0050] (12) The test chart according to any one of (7) to (11), further comprising: a center test patch situated at a center of the test chart and having a plurality of alignment features surrounding the center test patch.

[0051] (13) The test chart according to any one of (7) to (12), further comprising: a plurality of alignment features situated at each comer of the test chart.

[0052] (14) The test chart according to (13), wherein each of the plurality of alignment features includes at least two color tones.

[0053] (15) A dynamic range testing system comprising: a dark box housing configured to absorb light; a testing device within the dark box housing, the testing device including a camera; a light source configured to project light to the testing device; and a test chart situated between the light source and the testing device, wherein the test chart includes: a plurality of test patches arranged annularly on the test chart, each test patch having a brightness value, the plurality of test patches including: a first brightest test patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest test patch of the plurality of test patches, wherein, when moving clockwise around the plurality of test patches, brightness values of subsequent test patches decrease from the first brightest test patch to the darkest test patch, wherein the test patches are positioned such that light from test patches that is reflected off a flat lens element of the camera lands on portions of the test chart outside the plurality of test patches.

[0054] (16) The dynamic range testing system according to (15), wherein the plurality of test patches is an outer plurality of test patches arranged at a first distance from a center of the test chart, and wherein the test chart further includes an inner plurality of test patches arranged at a second distance from the center of the test chart, wherein the second distance is less than the first distance.

[0055] (17) The dynamic range testing system according to any one of (15) to (16), wherein the plurality of test patches further includes: a second brightest patch situated at a second end of the outer plurality of test patches, and wherein, when moving counter-clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the second bright test patch to the darkest test patch.

[0056] (18) A dynamic range test chart, the test chart comprising: a center; and a plurality of test patches, each test patch having a brightness value, wherein the test chart does not have any testpatches at locations that are the same distance from the center, but rotated 180°, from another test patch in the plurality of test patches.

[0057] (19) The test chart according to (18), wherein the plurality of test patches includes: an outer plurality of test patches annularly arranged on a first side of the test chart, and an inner plurality of test patches annularly arranged on a second side of the test chart.

[0058] (20) The test chart according to (19), wherein the first side of the test chart and the second side of the test chart are separated by an axis, and wherein the axis is misaligned with a center of the test chart.

[0059] (21) The test chart according to (19), wherein the outer plurality of test patches includes a first bright test patch, and wherein, when moving clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the first bright test patch to the darkest test patch included in the outer plurality of test patches.

[0060] (22) The test chart according to any one of (18) to (21), wherein the inner plurality of test patches includes a full black test patch.

[0061] (23) A dynamic range test chart, the test chart comprising: a plurality of test patches, each test patch having a brightness value, wherein the test patches are positioned such that light from test patches that is reflected off a flat lens element of a camera-under-test lands outside the plurality of test patches.

[0062] (24) The test chart according to (23), wherein the plurality of test patches includes: a first brightest test patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest test patch of the plurality of test patches.

[0063] (25) The test chart according to (24), wherein, when moving clockwise around the plurality of test patches, brightness values of subsequent test patches decrease from the first brightest test patch to the darkest test patch.

[0064] (26) The test chart according to any one of (23) to (25), wherein the plurality of test patches is an outer plurality of test patches arranged at a first distance from a center of the test chart, and wherein the test chart further includes an inner plurality of test patches arranged at a second distance from the center of the test chart, wherein the second distance is less than the first distance.

[0065] (27) The test chart according to any one of (23) to (26), wherein the plurality of test patches are arranged on a first side of the test chart opposite a second side, wherein the first sideof the test chart and the second side of the test chart are separated by an axis misaligned with a center of the test chart.

[0066] With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claims.

[0067] Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the technologies discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the application is capable of modification and variation.

[0068] All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

[0069] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments incorporate more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims arehereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

Claims

CLAIMSWhat is claimed is:

1. A dynamic range test chart, the test chart comprising: a plurality of test patches, each test patch having a brightness value, the plurality of test patches including: an outer plurality of test patches annularly arranged on a first side of the test chart, and an inner plurality of test patches annularly arranged on a second side of the test chart, wherein a brightness value of a darkest test patch included in the outer plurality of test patches is the same as a brightness value of a brightest test patch included in the inner plurality of test patches, wherein the test chart has a center, wherein the inner plurality of test patches are located closer to the center than the outer plurality of test patches, and wherein the test chart does not have any test patches at locations that are the same distance from the center, but rotated 180° about the center, from another test patch in the plurality of test patches; and a plurality of alignment features arranged in the comers of the test chart, wherein the first side of the test chart and the second side of the test chart are separated by an axis.

2. The test chart according to claim 1 , wherein the axis is offset from the center of the test chart.

3. The test chart according to any one of claims 1 to 2, wherein the outer plurality of test patches includes a first bright test patch, and wherein, when moving counter-clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the first bright test patch to a darkest test patch included in the outer plurality of test patches.

4. The test chart according to claim 3, wherein the outer plurality of test patches further includes a second bright test patch situated at an opposite end of the outer plurality of test patches than the first bright test patch, and wherein, when moving clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the second bright test patch to the darkest test patch included in the outer plurality of test patches.

5. The test chart according to any one of claims 1 to 4, wherein the inner plurality of test patches includes a full black test patch.

6. The test chart according to any one of claims 1 to 5, wherein the test chart further comprises a center test patch situated at the center of the test chart and having a second plurality of alignment features surrounding the center test patch.

7. A dynamic range test chart, the test chart comprising: a plurality of test patches annularly arranged on the test chart, each test patch having a brightness value, the plurality of test patches including: a first brightest test patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest test patch of the plurality of test patches, wherein, when moving counter-clockwise around the plurality of test patches, brightness values of subsequent test patches decrease from the first brightest test patch to the darkest test patch, wherein the test patches are positioned such that light from test patches that is reflected off a flat lens element of a camera-under-test lands on portions of the test chart that is outside the plurality of test patches.

8. The test chart according to claim 7, wherein the plurality of test patches is an outer plurality of test patches arranged at a first distance from a center of the test chart, and wherein the test chart further includes an inner plurality of test patches arranged at a second distance from the center of the test chart, wherein the second distance is less than the first distance.

9. The test chart according to claim 8, wherein a brightness value of the darkest test patch included in the outer plurality of test patches is the same as a brightness value of a brightest test patch included in the inner plurality of test patches.

10. The test chart according to any one of claims 7 to 9, wherein the plurality of test patches are arranged on a first side of the test chart opposite a second side, wherein the first side of the test chart and the second side of the test chart are separated by an axis offset from a center of the test chart.1 1 . The test chart according to any one of claims 7 to 10, wherein the plurality of test patches further includes: a second bright test patch situated at a second end of the outer plurality of test patches,and wherein, when moving clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the second bright test patch to the darkest test patch.

12. The test chart according to any one of claims 7 to 11, further comprising: a center test patch situated at a center of the test chart and having a plurality of alignment features surrounding the center test patch.

13. The test chart according to any one of claims 7 to 12, further comprising: a plurality of alignment features situated at each comer of the test chart.

14. The test chart according to claim 13, wherein each of the plurality of alignment features includes at least two color tones.

15. A dynamic range testing system comprising: a dark box housing configured to absorb light; a testing device within the dark box housing, the testing device including a camera; a light source configured to project light to the testing device; and a test chart situated between the light source and the testing device, wherein the test chart includes: a plurality of test patches arranged annularly on the test chart, each test patch having a brightness value, the plurality of test patches including: a first brightest test patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest test patch of the plurality of test patches, wherein, when moving counter-clockwise around the plurality of test patches, brightness values of subsequent test patches decrease from the first brightest test patch to the darkest test patch, wherein the test patches are positioned such that light from test patches that is reflected off a flat lens element of the camera lands on portions of the test chart outside the plurality of test patches.

16. The dynamic range testing system according to claim 15, wherein the plurality of test patches is an outer plurality of test patches arranged at a first distance from a center of the test chart, and wherein the test chart further includes an inner plurality of test patches arranged at a second distance from the center of the test chart, wherein the second distance is less than the firstdistance.

17. The dynamic range testing system according to claim 15 or 16, wherein the plurality of test patches further includes: a second bright test patch situated at a second end of the outer plurality of test patches, and wherein, when moving clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the second bright test patch to the darkest test patch.

18. A dynamic range test chart, the test chart comprising: a center; and a plurality of test patches, each test patch having a brightness value, wherein the test chart does not have any test patches at locations that are the same distance from the center, but rotated 180° about the center, from another test patch in the plurality of test patches.

19. The test chart according to claim 18, wherein the plurality of test patches includes: an outer plurality of test patches annularly arranged on a first side of the test chart, and an inner plurality of test patches annularly arranged on a second side of the test chart.

20. The test chart according to claim 19, wherein the first side of the test chart and the second side of the test chart are separated by an axis, and wherein the axis is offset from a center of the test chart.

21. The test chart according to claim 19, wherein the outer plurality of test patches includes a first bright test patch, and wherein, when moving clockwise around the outer plurality of test patches, brightness values of subsequent test patches decrease from the first bright test patch to the darkest test patch included in the outer plurality of test patches.

22. The test chart according to any one of claims 18 to 21 , wherein the inner plurality of test patches includes a full black test patch.

23. A dynamic range test chart, the test chart comprising: a plurality of test patches, each test patch having a brightness value, wherein the test patches are positioned such that light from test patches that is reflectedoff a flat lens element of a camera-under-test lands on portions of the test chart outside the plurality of test patches.

24. The test chart according to claim 13, wherein the plurality of test patches includes: a first brightest test patch of the plurality of test patches situated at a first end of the plurality of test patches, and a darkest test patch of the plurality of test patches.

25. The test chart according to claim 14, wherein, when moving clockwise around the plurality of test patches, brightness values of subsequent test patches decrease from the first brightest test patch to the darkest test patch.

26. The test chart according to any one of claims 23 to 25, wherein the plurality of test patches is an outer plurality of test patches arranged at a first distance from a center of the test chart, and wherein the test chart further includes an inner plurality of test patches arranged at a second distance from the center of the test chart, wherein the second distance is less than the first distance.

27. The test chart according to any one of 23 to 26, wherein the plurality of test patches are arranged on a first side of the test chart opposite a second side, wherein the first side of the test chart and the second side of the test chart are separated by an axis offset from a center of the test chart.

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