CN113840132A

CN113840132A - Test device and image test method for photographing device

Info

Publication number: CN113840132A
Application number: CN202010583753.5A
Authority: CN
Inventors: 杨中瑜
Original assignee: Oneplus Technology Shenzhen Co Ltd
Current assignee: Oneplus Technology Shenzhen Co Ltd
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2021-12-24

Abstract

The embodiment of the invention provides a testing device and an image testing method for a shooting device, wherein the testing device comprises: the test platform is provided with a plurality of installation parts, an observation main body and at least one graphic card, wherein the observation main body and the at least one graphic card are arranged on different installation parts and are not completely shielded from each other, the at least one graphic card is used as a foreground or a background, each graphic card comprises at least one row of inclined patterns, and the observation main body and the at least one graphic card are used as observation targets of the shooting device during testing through different relative distances. When the shooting device is tested, the main body and the background and/or the foreground under different distances can be conveniently set through the testing device, and then the obtained multiple groups of shot images are utilized to carry out depth of field relation analysis, so that an objective and feasible measuring method is provided for measuring the quality of the shot images.

Description

Test device and image test method for photographing device

Technical Field

The present invention relates to the field of image processing technologies, and in particular, to a test apparatus and an image test method for a camera.

Background

The depth of field is one of the important parameters of the camera lens, and one of the methods for obtaining the depth of field effect is the shot method. The shot view is a blurring effect caused by the fact that an image shot by a lens is not focused. Regarding the evaluation of the shot effect, DXO shot evaluation systems are currently frequently used, which use 6 indexes to determine the shot function, respectively: segmentation of the theme/background, equivalent aperture, fuzzy gradient, noise consistency, shot figures, and repeatability. However, these indicators are based on subjective tests, and thus there is a lack of an objective method for evaluating the effect or quality of a shot image.

Disclosure of Invention

In view of the above, the present invention provides a testing apparatus and an image testing method for a camera, which overcome the disadvantages of the prior art.

An embodiment of the present invention provides a test apparatus, including: the test system comprises a test platform provided with a plurality of installation parts, an observation main body and at least one graphic card, wherein the observation main body and the at least one graphic card are arranged on different installation parts and are not completely shielded from each other, and each graphic card comprises at least one row of inclined patterns; the observation main body and the at least one graphic card are arranged at different relative distances to serve as observation targets of the shooting device during testing.

In one embodiment, the upper surface of the test platform has a predetermined inclination angle with respect to the horizontal plane.

In the above embodiment, the testing apparatus further includes: and one or more combinations of scale indication structures, texture indication structures and light spot indication structures are arranged on the test platform with the preset inclination angle.

In one embodiment, the test apparatus further comprises: a tilt platform adjacent to the test platform, and one or more combinations of scale indicating structures, texture indicating structures, and spot indicating structures disposed on the tilt platform.

In one embodiment, the scale indicating structure, the texture indicating structure and the spot indicating structure are provided on the test platform or the tilt platform simultaneously.

In one embodiment, the scale indicating structure and the texture indicating structure are provided on the test platform or the tilt platform simultaneously.

In one embodiment, only the scale indicating structure is provided on the test platform or the tilt platform.

In one embodiment, the installation parts are arranged at intervals from front to back, and the installation parts are slots with preset lengths or jacks with preset numbers.

In the above embodiment, the foreground graphic card, the observation main body, or the background graphic card can move horizontally in the slot.

In one embodiment, the foreground graphic card, the observation main body and the background graphic card are detachably arranged on the test platform.

In one embodiment, the viewing body is a target graphic card including at least one row of the tilted pattern.

In one embodiment, the observation subject is a face head portrait model, if the upper surface of the test platform and the horizontal plane have a preset inclination angle, the face head portrait model is arranged on the test platform through a horizontal object placing table.

In one embodiment, the oblique pattern is a black rectangle rotated by a preset rotation angle in a preset rotation direction.

In the above embodiment, the center of the black rectangle is further provided with a lens focusing area.

In one embodiment, the preset rotation angle is greater than 0 degrees and less than 10 degrees.

Further, the value of the preset rotation angle is greater than or equal to 1 degree and less than or equal to 5 degrees.

In one embodiment, the graphic card comprises at least one row and at least two columns of the black rectangles, wherein the preset rotation direction and/or the preset rotation angle between at least one black rectangle and other black rectangles in the same row are different.

In one embodiment, the graphic card comprises at least two rows and at least two columns of the black rectangles, wherein at least one group of the black rectangles in adjacent rows has different preset rotation directions and/or preset rotation angles.

In one embodiment, the graphic card includes at least two rows and at least three columns of the black rectangles, wherein at least one set of the black rectangles located in adjacent rows has different preset rotation directions and/or preset rotation angles, and at least one black rectangle in at least one row has different preset rotation directions and/or preset rotation angles from other black rectangles in the same row.

In one embodiment, the texture indicating structure comprises a plurality of columns of repeated texture images, and the repeated texture images of each column comprise black and white square blocks.

In one embodiment, the scale indicating structure is a scale image;

in one embodiment, the light point indicating structure is a bulb line with a plurality of light-emitting lamps arranged at intervals.

An embodiment of the present invention further provides an image testing method, which uses the testing apparatus to test a shooting apparatus, and the method includes:

acquiring a plurality of sets of image data including the observation subject and a graphic card as a foreground or a background, which are shot by the shooting device, wherein the relative distance between the observation subject and the graphic card in each image is different;

respectively acquiring respective MTF values of the observation main body and the image card in each group of image data to obtain a plurality of groups of MTF values;

and obtaining corresponding distance-MTF curves according to the obtained multiple groups of MTF values, wherein the distance-MTF curves are used for calculating the depth-of-field relation between the observation subject and the foreground or the background.

acquiring image data which is shot by the shooting device and contains at least one inclined pattern in the observation main body and at least two image cards; at least one of the at least two graphic cards is used as a foreground, and at least one of the at least two graphic cards is used as a background;

acquiring respective MTF values of the observation subject and each graphic card in the image data;

and obtaining corresponding distance-MTF curves according to the obtained MTF values, wherein the distance-MTF curves are used for calculating the depth-of-field relation between the observation subject and the foreground and the background.

The embodiment of the invention has the following advantages:

the test device comprises a test platform provided with a plurality of installation parts, an observation main body and at least one graphic card serving as a foreground and/or a background are arranged on different installation parts and are not completely shielded with each other, and each graphic card comprises at least one row of inclined patterns. When the shooting device is tested, the main body and the background and/or the foreground can be set to be at different distances very conveniently through the testing device, the shooting device is utilized to shoot at least one inclined pattern in a chart card containing the observation main body and the foreground and/or the background at different distances from the observation main body, multiple groups of shot images can be obtained, further, MTF values of the observation main body and each chart card are calculated, a distance-MTF curve is obtained, the distance-MTF curve reflects the depth of field relation between the main body and the background and/or the foreground, and objective measurement of the shot images can be achieved. In addition, the accuracy and the like of the obtained objective measurement result can be further verified by utilizing subjective judgment by adding a scale indication structure, a texture indication structure and/or a light spot indication structure and the like on the test platform.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a first schematic structural diagram of a testing device according to an embodiment of the present invention;

FIG. 2 is a schematic side view of a test platform of the test apparatus of the present invention;

FIG. 3 is a schematic front view of a test platform of the test apparatus of the embodiment of the present invention;

FIGS. 4a to 4d are schematic diagrams illustrating four kinds of graphic card structures of a testing apparatus according to an embodiment of the present invention;

5a to 5b are schematic structural diagrams illustrating a human face head portrait model and a horizontal object placing table of the testing device according to the embodiment of the invention;

FIG. 6 is a second schematic diagram of a testing device according to an embodiment of the present invention;

FIG. 7 is a third schematic diagram of a testing device according to an embodiment of the present invention;

FIG. 8 is a first flowchart of an image testing method according to an embodiment of the present invention;

FIG. 9 shows a first schematic of a distance-MTF curve of an image testing method according to an embodiment of the present invention;

FIG. 10 shows a second flow diagram of an image testing method of an embodiment of the invention;

fig. 11 shows a second schematic diagram of a distance-MTF curve of the image testing method according to the embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the templates herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The resolution and contrast of the lens which have the greatest influence on the imaging quality of the photo, and the MTF value reflects the resolution and contrast of the lens, and is usually measured by a manufacturer under a strict test environment. The MTF, Modulation Transfer Function, is the Modulation Transfer Function, which can be used to evaluate the ability of the lens to restore the contrast, which represents the ability of the lens to represent light (e.g., black and white) in bright and dark. Generally, the higher the contrast, the clearer the picture content.

The depth of field refers to a clear range in front of or behind the subject when the subject is focused, and the range is called the depth of field. If the focusing subject is taken as the focusing center, the distance range which is close to the focusing center and still has clear imaging is called front depth of field, otherwise called rear depth of field, and the sum of the front depth of field and the rear depth of field is the range of the depth of field.

Example 1

Referring to fig. 1, the present embodiment provides a testing device 10, which can be used for lens performance testing of a camera, especially for evaluating the quality of a shot image, and provides an objective measuring method based on the testing device 10. The test apparatus 10 will be described in detail below.

Exemplarily, as shown in fig. 1, the test apparatus 10 includes: a test platform 110, and an observation subject and at least one graphic card 120 disposed on the test platform 110. The observation main body and each graphic card are arranged at different relative distances to serve as observation targets of the shooting device during testing. The foreground is located in front of the observation main body and the background is located behind the observation main body by taking the observation main body as a reference. Any one of the graphic cards 120 may serve as a background or background of the observation subject, depending on whether it is located in front of or behind the observation subject.

The number of the graphic cards 120 can be set according to different image testing methods, for example, when there is one graphic card 120, the distance between the graphic card 120 and the observation subject can be changed by moving the front and back positions, so as to form different depth-of-field relationships. Alternatively, when multiple image cards 120 are simultaneously arranged, one part can be used as the foreground and the other part as the background, and different combinations of depths of field can be formed. In the actual test process, when the observation subject is also a graphic card, a plurality of graphic cards 120 can be simultaneously arranged on the test platform 110, so that the observation subject does not need to be moved at every time in the shooting process, only the observation subject needs to be replaced by the graphic cards 120 at different positions, and images with different depth of field effects can be conveniently and quickly obtained, thereby greatly improving the test efficiency and the like.

The test platform 110 is mainly used for fixing and supporting the observation main body and each graphic card 120 and the like, and is convenient for testers to shoot panoramic images and the like. In this embodiment, the testing platform 110 is provided with a plurality of mounting portions 111, and the mounting portions 111 are spaced from each other in a front-to-back direction. The number of the mounting portions 111 may be, for example, 3 to 10, and may be specifically designed according to actual requirements. The above-described observation subject and each of the graphic cards 120 as the foreground or the background will be respectively disposed at different mounting portions 111 and not be completely shielded from each other. It is understood that the incomplete occlusion herein means that at least one oblique pattern exists in each card within the range of the photographing angle of view when photographing is performed by the photographing apparatus.

Exemplarily, the upper surface of the testing platform 110 and a horizontal plane contacting the ground have a preset inclination angle, and the value range of the preset inclination angle θ is: theta is more than or equal to 0 degree and less than 90 degrees. In one embodiment, the preset inclination angle θ is greater than 0 degrees and less than 90 degrees, and the upper surface of the testing platform 110 on which the plurality of mounting portions 111 are disposed is inclined. The mounting portions 111 may be provided at different positions of the inclined surface, respectively, as shown in fig. 2. For example, when the test platform 110 has a longitudinal length of 300cm, the mounting portions 111 may be disposed at positions of 30cm, 50cm, 100cm, 150cm, 200cm, and 300cm, respectively. The height of the testing platform 110 can be set according to practical requirements, and is not limited herein.

It can be understood that, since the upper surface of the testing platform 110 is inclined, the heights of the installation parts 111 will be different, so that the height difference between the graphic card 120 and the observation main body arranged on different installation parts 111 will be generated, and further, the graphic card 120 and the observation main body as the foreground or the background can be not shielded or not completely shielded from each other. In addition, the non-shielding is realized by utilizing the height difference, and the requirement on the transverse width of the test platform 110 can be reduced for the scene with a plurality of graphic cards 120 arranged in front and back.

In another embodiment, the value of the preset inclination angle θ may also be 0 degree, that is, the upper surface of the testing platform 110 is parallel to the horizontal ground, as shown in fig. 3, at this time, the tester may adjust the positions of the observation main body and the graphic card 120 in the horizontal direction according to the actual situation, so as to avoid the phenomenon of complete shielding before and after the occurrence.

In one embodiment, the observation subject and the graphic card 120 as the foreground or the background are detachably disposed on the mounting portion 111 of the testing platform 110, which facilitates to remove or dispose a plurality of graphic cards 120 in a corresponding amount or to replace different types of observation subjects according to actual testing requirements.

With respect to the mounting portion 111, in an alternative embodiment, as shown in fig. 1, the mounting portion 111 is a slot with a predetermined length, wherein the predetermined length is less than or equal to the lateral width (i.e. the width in the horizontal direction) of the testing platform 110. When the length of the slot is greater than the width of the graphic card 120, the graphic card 120 or the observation main body can horizontally move in the corresponding slot, so that the position adjustment can be facilitated, and the phenomenon of front and back shielding is avoided.

In another alternative embodiment, the mounting portion 111 may be a predetermined number of insertion holes, and the insertion holes are all located on the same horizontal line. It will be appreciated that adjustment of the horizontal position thereof may be achieved by inserting the graphic card 120 or the viewing body into different receptacles in the same mounting portion 111. In addition, the size of the receptacle is generally matched to the size of the inserted graphics card 120 or viewing body, and is not limited herein.

Each card 120 includes at least one row of slanted patterns, where the slanted patterns are mainly used for focusing and focusing of the camera. Illustratively, the background color of the graphic card 120 is generally white, and regarding the tilted pattern in the graphic card 120 described above, the tilted pattern is, in one embodiment, a black rectangle rotated by a preset rotation angle in a preset rotation direction. It is understood that the rectangle may be rectangular or square. By selecting black which can form obvious chromatic aberration, observation, subsequent image analysis and processing and the like can be facilitated. Of course, the oblique pattern may be other colors, and is not limited herein.

For example, the preset rotation direction of the black rectangle may be clockwise or counterclockwise along the center of the rectangle or around one of the corners, which is not limited herein and may be determined according to actual requirements. For the preset rotation angle, in an optional embodiment, the value range is greater than 0 degrees and less than 10 degrees, that is, the black rectangle can be rotated within 10 degrees at will. Preferably, the value is 1 degree or more and 5 degrees or less.

It can be understood that after the black rectangle is rotated according to the preset rotation angle, the side length of the black rectangle is in an inclined setting state, so that the edge imaging capability of the lens of the shooting device can be conveniently tested.

In some embodiments, the center of the black rectangle is further provided with a focusing region, and the focusing region is exemplarily configured by a pattern of alternating black and white, but is not limited thereto. The focusing area can provide a focusing point for testing the lens, and is convenient for testing the central imaging capability of the lens of the shooting device.

It is understood that only one tilted pattern may be included in one card 120, or a plurality of tilted patterns may be included, and preferably, a plurality of tilted patterns may be provided in each card 120. For the graphic card 120 containing a plurality of oblique patterns, especially, the oblique patterns are not all completely the same, so that more test points can be provided within the range of the shot picture, and whether the depth-of-field algorithm software adopted by the shooting device is normal can be judged through the more test points. For example, in general, when focusing an observation subject, a plurality of tilted patterns in the same foreground graphic card 120 should each exhibit a blurring effect, without the phenomenon that one of the tilted patterns is very clear and the other tilted patterns are blurred. In addition, more test points can be used for judging whether the deformation of the edge under the same focal length is abnormal or not, and more analyzable data can be provided for software calibration, so that a more accurate judgment result can be obtained, and the shooting performance of the shooting device can be better evaluated.

Due to the difference in the number of oblique patterns, the preset rotation direction and the preset rotation angle, various forms of the graphic cards 120 having different sizes can be formed. In the following, the oblique pattern of black rectangles is taken as an example to list several possible cards 120, but it should be understood that the existence form is not limited thereto.

Illustratively, the rotation direction and the rotation angle of each black rectangle in the graphic card 120 can be arbitrarily set within a set value range. For example, the black rectangles have the same rotation angle and the same rotation direction, or the black rectangles have different rotation angles and the same rotation direction, or the black rectangles have the same rotation angle and the same rotation direction, and the like.

In a first embodiment, the graphic card 120 includes at least one row and at least two columns of black rectangles, wherein at least one black rectangle is rotated in a different direction and/or angle than the other black rectangles in the same row. For example, as shown in fig. 4a, the rotation direction of the first black rectangle is counterclockwise, and the rotation direction of the second black rectangle is clockwise; alternatively, the rotation angle of the first black rectangle is 2 degrees, and the rotation angle of the second black rectangle is 5 degrees, and so on.

In a second embodiment, the graphic card 120 includes at least two rows and at least two columns of black rectangles, wherein at least one group of black rectangles in adjacent rows have different rotation directions and/or rotation angles. For example, as shown in fig. 4b, the rotation directions of the black rectangles of the first and second columns are opposite, and the rotation angles of the two black rectangles of the second column are different, etc.

In a third embodiment, the graphic card 120 includes at least two rows and at least three columns of black rectangles, wherein at least one group of the black rectangles in the adjacent rows has different rotation directions and/or rotation angles, and at least one black rectangle in at least one row has a different rotation direction and/or rotation angle from the other black rectangles in the same row. For example, as shown in fig. 4c, the rotation direction of the first and second columns is opposite, the rotation direction of the third column is the same, and the rotation direction of the first of the second rows is opposite to the rotation direction of the third, or a black rectangle comprising four rows and five columns, as shown in fig. 4d, etc.

It will be appreciated that the above-listed embodiments are merely illustrative, and that in practice, other arrangements may be made based on the oblique pattern described above. When the number of the oblique patterns is larger, the size of the graphic card 120 is generally larger, and of course, the size of the oblique patterns may be changed according to actual requirements to adapt to the graphic card 120 with the corresponding size, and the invention is not limited herein.

For the observation subject, in one embodiment, the observation subject is a target graphic card, that is, a graphic card 120 including the same oblique pattern as described above is used. Exemplarily, when at least three graphic cards 120 are disposed on the testing platform 110, three graphic cards 120 may be selected from the graphic cards 120 as the foreground graphic card, the target graphic card, and the background graphic card.

In another embodiment, the observation subject may also be a face avatar model, as shown in fig. 5a, in this case, the observation subject is mainly used for testing face tracking, depth of field effect, and the like of the portrait mode. Exemplarily, for the testing platform 110 with a horizontal plane upper surface, the facial avatar model can be directly disposed on the testing platform 110. If the upper surface of the testing platform 110 is disposed obliquely, optionally, the testing apparatus 10 further includes a horizontal object stage, as shown in fig. 5b, the facial avatar model will be disposed on the oblique testing platform 110 via a horizontal object stage.

In addition, when the inclined test platform 110 is adopted, if the distance between the graphic card 120 as the foreground and the graphic card 120 as the background is relatively long, the graphic card 120 in the lower position may not enter the lens range, so that the graphic card 120 with the smaller size can be extended in height, thereby ensuring that the background graphic card, the observation subject and the foreground graphic card are all located in the same lens range.

The testing device 10 can conveniently set the main body and the background and/or the foreground under different distances, and further carry out the depth of field relation analysis by using the obtained multiple groups of shot images. The test device 10 can be used for lens test of a shooting device, and the obtained depth-of-field relation analysis result can be used for objectively evaluating the quality of a shot image and the like of the shooting device.

Exemplarily, the observation subject and at least one of the graphic cards 120 are disposed at different positions, and then MTF values of the observation subject and each graphic card 120 at different distances are obtained to draw a corresponding distance-MTF curve, and a trend of the distance-MTF curve can objectively reflect a depth-of-field relationship between the observation subject and a background or between the observation subject and the foreground or between the observation subject and the background. By judging whether the curve trend accords with the actual optical imaging principle or not, objective evaluation on the quality of the shot image shot by the shooting device can be realized.

Example 2

Referring to fig. 6 and 7, based on the testing device 10 of the embodiment 1, the testing device 10 of the present embodiment further includes a subjective testing part, through which the accuracy of the objective measurement result of the embodiment 1 can be roughly determined, and the accuracy of the objective measurement algorithm, the algorithm optimization, and the like can be verified.

In one embodiment, when the upper surface of the testing platform 110 has a predetermined inclination angle with respect to the horizontal plane, that is, when an inclined testing platform is used, the testing device 10 further includes: one or more combinations of scale indicating structures 130, texture indicating structures 140, and spot indicating structures 150 disposed on the test platform 110.

In another embodiment, when the upper surface of the testing platform 110 is a horizontal plane, as shown in fig. 7, the testing device 10 further includes: a tilt stage adjacent to the test stage 110, and one or more combinations of scale indicating structures 130, texture indicating structures 140, and spot indicating structures 150 disposed on the tilt stage.

For the presence of these three indicator structures, in a preferred embodiment, the subjective testing portion includes both: the scale indicating structure 130, the texture indicating structure 140 and the spot indicating structure 150 are disposed on the test platform 110 or the inclined platform at the same time. Of course, there may be one or two of the three, for example, the subjective test portion may include only the scale indicating structures 130 and the texture indicating structures 140, or only the scale indicating structures 130, and so on.

The scale indicating structure 130 is mainly used to subjectively determine whether the continuity processing of the depth-of-field algorithm used in the objective measurement process is good or not. In an actual imaging device, the continuity of the depth-of-field algorithm is mainly reflected in the continuity of blurring strength, and when a picture is blurred, the blurring degree is usually gradually strengthened or weakened. The scale indicating structure 130 is exemplarily a scale image, for example, the background of the scale image may be set to be black, and the scale lines will be white, but not limited thereto.

The texture indicating structure 140 is mainly used to subjectively determine whether there is unexpected processing deficiency in the depth of field algorithm used in the objective measurement process. The texture indicating structure 140 may comprise a plurality of columns of repeated texture images, wherein each column of repeated texture images comprises black and white blocks.

The spot indication structure 150 is mainly used to subjectively determine whether spot processing by a depth of field algorithm employed in the objective measurement process is good or not, and the like. The light point indicating structure 150 may be a bulb line with a plurality of light emitting lamps spaced apart from each other, for example, the light emitting lamps may be light emitting diodes.

It can be understood that the subjective indication structures are used for subjectively and auxiliary judging on different aspects of continuity processing, unexpected processing deficiency, facula processing and the like of a depth of field algorithm adopted in the objective measurement process, so that the accuracy of the result of objective measurement can be better ensured.

Example 3

Referring to fig. 8, based on the testing device 10 of the above embodiment 1 or 2, this embodiment provides an image testing method, which can be applied to testing of a shooting device in different situations, specifically including objective evaluation of quality of a shot image shot by the shooting device. The shooting device may be a camera function device in various terminal devices such as a mobile phone and a tablet, or an optical camera. In the present embodiment, the image test is mainly performed by one observation subject and one graphic card 120, and the method will be described below.

In step S110, a plurality of sets of image data including an observation subject and one card 120 as a foreground or a background photographed by a photographing device are acquired, wherein the distance between the observation subject and the card 120 in each image is different.

Exemplarily, as shown in fig. 2, if the test platform 110 has 7 mounting parts 111, the observation subject and the graphic card 120 as a foreground or a background can be disposed at different mounting parts 111, taking the observation subject as a target graphic card as an example, for example, the target graphic card can be fixedly placed at 150cm and another graphic card 120 can be sequentially disposed at several positions of 30cm, 50cm, 100cm, 150cm, 200cm, 250cm and 300cm, and 7 images can be obtained by focusing the target graphic card and then shooting. Where the distance between the viewing subject and the card 120 as the foreground or background is different in each image, it can be understood that the other card 120 may change from foreground to background or from background to foreground as the position changes. The distance of the other card at 100cm from the target card (150cm) is only numerically equal to the distance at 200cm, but the front and back positions of the two cards are distinguished.

Step S120, respectively obtaining respective MTF values of the observation subject and the graphic card 120 in each group of image data, to obtain a plurality of groups of MTF values.

Image data of a plurality of images acquired may be analyzed by a tool such as Imatest, wherein each image includes two graphics cards, and 2 MTF values are obtained correspondingly. For multiple images, multiple sets of MTF values can be obtained. It can be understood that since the position of the target card is fixed, that is, the distance from the lens of the camera to the observing subject is not changed, the MTF value of the observing subject in each image is the same, and the MTF value of the other card 120 is different.

Step S130, obtaining corresponding distance-MTF curves according to the obtained multiple groups of MTF values, wherein the distance-MTF curves are used for reflecting the depth of field relation between the observation subject and the foreground or the background.

Due to the different relative positions of the graphic card 120 and the observation subject, the corresponding depth of field effect is also different. In order to objectively reflect the depth-of-field relationship, the present embodiment provides a distance-MTF curve, by which the depth-of-field relationship between the observation subject and the background or the foreground can be reflected.

Exemplarily, as shown in fig. 9, the abscissa of the distance-MTF curve is the set distance of the other graphic card 120, and the ordinate is the MTF value at the corresponding set distance. As can be seen from the curve, the MTF value of the other graphic card 120 is larger as the distance from the observation subject is closer, which means that the contrast of the other graphic card 120 is larger at this time, and the view is clearer; and when the MTF value of the other card 120 is maximized, just when the MTF value is in or close to the same plane, which is consistent with the actual optical imaging principle, in other words, the depth-of-field relationship between the subject of observation and the foreground or background can be objectively reflected by the distance-MTF curve. In the actual application process, the distance-MTF curve obtained by obtaining the image testing device can be used for objectively evaluating the accuracy of software processing of a depth-of-field algorithm in the shooting device, the lens performance and the like.

Example 4

Referring to fig. 10, based on the testing apparatus 10 of the above embodiment 1 or 2, the present embodiment provides an image testing method, which is different from the method of the above embodiment 3 in that when performing an image test, a plurality of graphic cards 120 are placed on the testing platform 110 at the same time, so that it is not necessary to move the graphic cards 120 each time to form different depth-of-field combinations. Because each graphic card 120 corresponds to one MTF value, a group of MTF values can be obtained by shooting an image including an observation subject and a plurality of graphic cards 120, and if the graphic cards 120 at different positions are sequentially selected as the observation subjects, a plurality of groups of MTF values and a plurality of distance-MTF curves can be obtained without any movement, so that the test efficiency can be greatly improved, and the like. The method is described in detail below.

Step S210, acquiring image data including an observation subject and at least one tilted pattern of at least two graphics cards 120 captured by a camera, where at least one graphics card 120 of the at least two graphics cards 120 is used as a foreground and at least one graphics card 120 is used as a background.

In this embodiment, the test platform 110 is provided with an observation subject and a plurality of graphic cards 120, wherein at least one graphic card 120 exists as a foreground and at least one graphic card exists as a background in the graphic cards 120. Exemplarily, taking the test platform 110 provided with 7 mounting portions 111 as an example, if the observation subject is also the graphic card 120, 7 graphic cards 120 can be set for image test. When taking an image, any one of the 2 nd to 6 th image cards 120 may be selected as an observation subject, and an image including at least one oblique pattern of each of the observation subject and the other 6 image cards 120 may be obtained by focusing and taking an image of an oblique pattern of the observation subject.

Step S220, obtain the respective MTF values of the observation subject and each graphic card 120 in the image data.

Illustratively, by analyzing the image data with a tool such as Imatest, the MTF value corresponding to each card 120 in the image can be obtained, and in the example of the above 7 cards 120, 7 MTF values can be obtained.

And step S230, obtaining corresponding distance-MTF curves according to the obtained MTF values, wherein the distance-MTF curves are used for reflecting the depth of field relation between the observation subject and the foreground and the background.

Since the relative position of each graphic card 120 and the graphic card 120 where the observation subject is located is different, similarly, the distance-MTF curve shown in fig. 9 can be obtained by these 7 MTF values and the setting distance of each graphic card 120. The trend of the distance-MTF curve objectively reflects the depth-of-field relationship between the observation subject and the foreground and the background.

In an alternative embodiment, after obtaining a distance-MTF curve corresponding to one image for the plurality of graphics cards 120, the graphics cards 120 at different positions may be replaced with a group of MTF values for each image, so that a plurality of curves may be obtained, and at this time, the curves may be presented by three-dimensional coordinates, as shown in fig. 11, where an X axis represents a distance between the observation subject and the foreground and/or the background, a Y axis represents an MTF value, and a Z axis represents a position where the observation subject is located. As can be seen from the curves in fig. 11, each card 120 has the maximum MTF value only when it is used as the observation subject, which is consistent with the actual optical imaging principle. And the depth of field relation between the observation subject and the foreground or the background is distributed in a convex shape, and the depth of field effect is least obvious when the background or the foreground and the observation subject are closer to the same plane, which is also in accordance with the actual optical imaging theory.

In all examples shown and described herein, any particular value should be construed as merely exemplary, and not as a limitation, and thus other examples of example embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. A test device for a camera, comprising: the test system comprises a test platform provided with a plurality of installation parts, an observation main body and at least one graphic card, wherein the observation main body and the at least one graphic card are arranged on different installation parts and are not completely shielded from each other, and each graphic card comprises at least one row of inclined patterns; the observation main body and the at least one graphic card are arranged at different relative distances to serve as observation targets of the shooting device during testing.

2. The testing device of claim 1, wherein the upper surface of the testing platform has a predetermined angle of inclination with respect to a horizontal plane.

3. The testing device of claim 2, further comprising: and one or more combinations of scale indication structures, texture indication structures and light spot indication structures are arranged on the test platform with the preset inclination angle.

4. The testing device of claim 1, further comprising: a tilt platform adjacent to the test platform, and one or more combinations of scale indicating structures, texture indicating structures, and spot indicating structures disposed on the tilt platform.

5. The testing device of any one of claims 1 to 4, wherein the mounting portions are spaced back and forth, and the mounting portions are slots of a predetermined length or a predetermined number of insertion holes.

6. The test device of any one of claims 1 to 4, wherein each of the graphics cards and the viewing body are removably disposed on the test platform.

7. The testing device of claim 1, wherein the observation subject is a target graphic card, the target graphic card including at least one row of the tilted patterns therein.

8. The testing device according to claim 1 or 2, wherein the observation subject is a human face head portrait model, and if the upper surface of the testing platform has a preset inclination angle with the horizontal plane, the human face head portrait model is arranged on the testing platform through a horizontal object placing table.

9. The test device according to claim 1 or 7, wherein the oblique pattern is a black rectangle rotated by a preset rotation angle in a preset rotation direction.

10. The test device of claim 9, wherein the center of the black rectangle is further provided with a lens focusing area.

11. The testing device of claim 9, wherein the predetermined rotation angle is greater than 0 degrees and less than 10 degrees.

12. The test device of claim 9, wherein the graphic card comprises at least one row and at least two columns of the black rectangles, wherein the preset rotation direction and/or the preset rotation angle between at least one black rectangle and other black rectangles in the same row are different.

13. The test apparatus as claimed in claim 9, wherein the graphic card comprises at least two rows and at least two columns of the black rectangles, wherein at least one group of the black rectangles in adjacent rows have different preset rotation directions and/or preset rotation angles.

14. The test device according to claim 3 or 4, wherein the texture indicating structure comprises a plurality of columns of repeated texture images, the repeated texture images of each column comprising a number of black and white alternating squares;

the scale indication structure is a scale image;

the light spot indicating structure is a bulb line which is formed by a plurality of light-emitting lamps at intervals.

15. An image testing method characterized by performing a test of a photographing apparatus using the testing apparatus according to any one of claims 1 to 14, the method comprising:

acquiring a plurality of groups of image data which are shot by a shooting device and comprise the observation subject and a picture card as a foreground or a background, wherein the distance between the observation subject and the picture card in each image is different;

and obtaining corresponding distance-MTF curves according to the obtained multiple groups of MTF values, wherein the distance-MTF curves are used for reflecting the depth-of-field relation between the observation subject and the foreground or the background.

16. An image testing method characterized by performing a test of a photographing apparatus using the testing apparatus according to any one of claims 1 to 14, the method comprising:

acquiring image data which is shot by the shooting device and contains at least one inclined pattern in the observation main body and at least two image cards, wherein at least one image card is used as a foreground, and at least one image card is used as a background;

and obtaining corresponding distance-MTF curves according to the obtained MTF values, wherein the distance-MTF curves are used for reflecting the depth-of-field relation between the observation subject and the foreground and the background.