Projection image correction method

Abstract

The embodiment of the invention belongs to the projection display technology, and provides a projection image correction method. The method comprises the following steps: shooting after projecting a feature chart set comprising at least one pure color chart, and determining image coordinates corresponding to four corner points of a projection screen according to a first shot image set; and obtaining a color distinguishing gray threshold value corresponding to each angular point. And projecting and shooting the graphic cards in the second feature graphic card set and the third feature graphic card set to obtain a second shot image set and a third shot image set, and correcting the projected image by combining the image coordinates and color distinguishing gray threshold values corresponding to the four angular points. According to the scheme, even under the influence of ambient light, the second shot image set and the third shot image set can be processed according to the color distinguishing gray threshold, and the image shot by using the ultra-wide-angle lens under the influence of the ambient light is corrected.

Description

Technical Field

[0001] The embodiments of the present application relate to projection display technology, and more specifically, to a projection image correction method. Background Art

[0002] With the development of science and technology and the improvement of people's living standards, various types of projection equipment have emerged. Among them, ultra-short-throw projection equipment such as laser TVs and projectors made with ultra-short-throw lenses are deeply loved by people for their eye protection, bright colors, and power saving. Ultra-short-throw projection equipment includes a projection host and a projection screen. When the projection equipment is used for the first time or the position of the projection host is moved, the image projected by the projection host cannot completely match the projection screen, affecting the display effect, and the projection image needs to be corrected.

[0003] In the prior art, an ultra-short-throw projection device usually projects a picture card with feature points, and the user uses a terminal device with a camera to capture the projected image, and then identifies the feature points therein, and then determines the correction coordinates for correction. This process requires the participation of the user and the terminal device, and the process is cumbersome, so the ultra-short-throw projection device's own camera can be used to capture the projected image for correction. In order to be able to fully capture the projected image, the camera usually uses an ultra-wide-angle camera, and in order to achieve a better display effect, the ultra-short-throw projection device is usually equipped with a projection screen for image display. The projection screen is generally a Fresnel screen. The light projected by the ultra-short-throw projection device is incident on the projection screen and then reflected to the human eye, meeting the user's display requirements for the projected image. However, the projection screen will also reflect ambient light such as lights and strong light. When using an ultra-wide-angle camera to capture the projection screen, it is also easily affected by ambient light, resulting in the feature points in the captured projection image being covered by ambient light and cannot be recognized, and cannot be corrected.

[0004] Therefore, there is an urgent need for a projection image correction method that can perform image correction on images captured by an ultra-wide-angle lens under the influence of ambient light. Summary of the invention

[0005] An embodiment of the present application provides a projection image correction method for solving the problem of an urgent need for a projection image correction method capable of performing image correction on an image captured by an ultra-wide-angle lens under the influence of ambient light.

[0006] In a first aspect, an embodiment of the present application provides a projection image correction method, which is applied to an ultra-short-throw projection device, wherein the ultra-short-throw projection device includes a projection host and a projection screen, wherein the projection host includes a projection unit and an ultra-wide-angle camera, and the method includes:

[0007] Projecting a card in a first feature card set onto the projection screen, photographing the projection screen to obtain a first captured image set, and determining image coordinates corresponding to four corner points of the projection screen according to the first captured image set; wherein the first feature card set includes at least one pure color card, and the card projected onto the projection screen covers the projection screen;

[0008] Obtain the color distinction grayscale thresholds corresponding to the four corner points;

[0009] The cards in the second feature card set and the third feature card set are sequentially projected onto the projection screen in the order in the card set; the cards in the second feature card set projected onto the projection screen are sequentially photographed to obtain a second captured image set, and the cards in the third feature card set projected onto the projection screen are sequentially photographed to obtain a third captured image set;

[0010] The projection image is corrected according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set.

[0011] The beneficial effects of this embodiment are as follows: by projecting a feature card set including at least one pure color card, and then photographing the projected image, the image coordinates corresponding to the four corner points of the projection screen are determined; and then the color distinction grayscale threshold corresponding to each corner point is obtained. The cards in the second feature card set and the third feature card set are then projected in the order in the card set, and the projected images are photographed in sequence to obtain the second captured image set and the third captured image set, and then the projected image is corrected in combination with the image coordinates corresponding to the four corner points and the color distinction grayscale threshold. Compared with the prior art that is affected by ambient light, this solution adopts the method of first obtaining the color distinction grayscale threshold, and then correcting the projected image in combination with the second captured image set and the third captured image set, so that even under the influence of ambient light, the second captured image set and the third captured image set can be processed according to the color distinction grayscale threshold, thereby realizing image correction of images captured using an ultra-wide-angle lens under the influence of ambient light.

[0012] In some embodiments of the present application, determining the image coordinates corresponding to the four corner points of the projection screen according to the first captured image set includes:

[0013] Performing grayscale conversion on any one of the first captured images to obtain a first grayscale image;

[0014] Perform edge detection on the first grayscale image to determine image coordinates corresponding to four corner points of the projection screen.

[0015] The beneficial effect of this embodiment is as follows: by first performing grayscale conversion on the images in the first captured image set and then performing edge detection, the image coordinates corresponding to the four corner points of the projection screen can be obtained, which can effectively improve the accuracy of the image coordinates of the obtained corner points.

[0016] In some embodiments of the present application, the first feature image card set includes at least two pure color image cards with different grayscale values;

[0017] The obtaining of the color distinction grayscale thresholds corresponding to the four corner points includes:

[0018] Performing grayscale conversion on each image in the first captured image set to obtain at least two second grayscale images;

[0019] Determine at least two grayscale values ​​corresponding to each of the four corner points according to the image coordinates corresponding to the four corner points and each second grayscale image;

[0020] For each of the four corner points, an average value of at least two grayscale values ​​corresponding to the corner point is determined as a color distinguishing grayscale threshold corresponding to the corner point.

[0021] The beneficial effects of this embodiment are as follows: by performing grayscale conversion on each image in the first captured image set, and then using the converted second grayscale image in combination with the image coordinates corresponding to the four corner points, multiple grayscale values ​​corresponding to each corner point are obtained, and then the average value of the multiple grayscale values ​​is used as the color distinction grayscale threshold for the corner point, which can effectively improve the accuracy of the obtained color distinction grayscale threshold.

[0022] In some embodiments of the present application, obtaining the color distinction grayscale thresholds corresponding to the four corner points includes:

[0023] For each of the four corner points, a preset grayscale threshold corresponding to the stored corner point is obtained as the color distinguishing grayscale threshold corresponding to the corner point.

[0024] The beneficial effect of this embodiment is that by using the preset grayscale threshold corresponding to the stored corner point as the color distinction grayscale threshold corresponding to the corner point, the accuracy of the obtained color distinction grayscale threshold can be effectively improved.

[0025] In some embodiments of the present application, each image card in the second characteristic image card set is an image card in which vertical first stripes and vertical second stripes are alternately placed, the grayscale value of the first stripes in each image card in the second characteristic image card set is the same, the width of the stripes in the first image card in the second characteristic image card set is a first preset width, for each image card in the second characteristic image card set except the first image card, the width of the stripes in the image card is half of the width of the stripes in the previous image card of the image card, and the grayscale value of the first stripes is different from that of the second stripes;

[0026] Each card in the third characteristic card set is a card in which horizontal third stripes and horizontal fourth stripes are placed alternately, the grayscale value of the first stripe in each card in the third characteristic card set is the same, the stripe width in the first card in the third characteristic card set is the second preset width, for each card in the third characteristic card set except the first card, the stripe width in the card is half of the stripe width in the previous card of the card, and the grayscale value of the third stripe is different from that of the fourth stripe.

[0027] The beneficial effects of this embodiment are as follows: by making the stripe width of a card in the card set half the stripe width of the previous card, and by placing stripes with two different grayscale values ​​alternately, the correction coordinates obtained based on the cards in the card set can be more accurate, and the correction accuracy can be further improved.

[0028] In some embodiments of the present application, the correction of the projected image according to the image coordinates and color-differentiated grayscale thresholds corresponding to the four corner points, and the second captured image set and the third captured image set includes:

[0029] Determine the correction coordinates corresponding to the four corner points according to the image coordinates corresponding to the four corner points and the color distinction grayscale threshold, as well as the second captured image set and the third captured image set;

[0030] The projection image is corrected according to the correction coordinates corresponding to the four corner points.

[0031] The beneficial effects of this embodiment are as follows: by determining the correction coordinates corresponding to the four corner points based on the image coordinates and color distinction grayscale thresholds corresponding to the four corner points, as well as the second captured image set and the third captured image set, and then using the correction coordinates for correction, the correction is more accurate and the correction effect is better.

[0032] In some embodiments of the present application, determining the correction coordinates corresponding to the four corner points according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set, includes:

[0033] For each of the four corner points, determining, according to the image coordinates corresponding to the corner point, a first grayscale value of the corner point in each image in the second captured image set, and a second grayscale value of the corner point in each image in the third captured image set;

[0034] Determine a first coding value corresponding to the corner point according to the first gray value and a color-differentiated gray threshold corresponding to the corner point;

[0035] Determine a second encoding value corresponding to the corner point according to the second grayscale value and a color-distinguishing grayscale threshold corresponding to the corner point;

[0036] The first coding value and the second coding value are decoded to obtain the corrected coordinates corresponding to the corner point.

[0037] The beneficial effects of this embodiment are as follows: the first grayscale value of the corner point in each image in the second captured image set, the second grayscale value of the corner point in each image in the third captured image set, and the color-distinguishing grayscale threshold corresponding to the corner point are used to determine the first coding value and the second coding value corresponding to the corner point, and then they are decoded to obtain the corrected coordinates, making the corrected coordinates more accurate.

[0038] In some embodiments of the present application, the determining the first code value corresponding to the corner point according to the first gray value and the color corresponding to the corner point to distinguish the gray threshold includes:

[0039] For each image in the second captured image set, if the first grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, then determining the first sub-code corresponding to the image to be 1;

[0040] If the first grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the first subcode corresponding to the image is determined to be 0;

[0041] According to the arrangement order of each image in the second captured image set, the first sub-code corresponding to each image is sorted to obtain the first code value corresponding to the corner point.

[0042] The beneficial effects of this embodiment are as follows: by determining the first sub-code to be 0 or 1 through the relationship between the first grayscale value and the color distinction threshold, and then sorting the first sub-code according to the arrangement order of each image in the second captured image set to obtain the first code value, which can effectively improve the accuracy of the first code value and thus improve the correction effect.

[0043] In some embodiments of the present application, the determining the second encoding value corresponding to the corner point according to the second gray value and the color corresponding to the corner point to distinguish the gray threshold includes:

[0044] For each image in the third captured image set, if the second grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, then determining the second sub-code corresponding to the image to be 1;

[0045] If the second grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the second sub-code corresponding to the image is determined to be 0;

[0046] According to the arrangement order of each image in the third captured image set, the second sub-code corresponding to each image is sorted to obtain the second code value corresponding to the corner point.

[0047] The beneficial effects of this embodiment are as follows: the second sub-code is determined to be 0 or 1 through the size relationship between the second grayscale value and the color distinction grayscale threshold, and then the second sub-code is sorted according to the arrangement order of each image in the third captured image set to obtain the second code value, which can effectively improve the accuracy of the second code value and thus improve the correction effect.

[0048] In some embodiments of the present application, decoding the first coded value and the second coded value to obtain the corrected coordinates corresponding to the corner point includes:

[0049] Convert the first code value into a decimal system to obtain a corrected horizontal coordinate corresponding to the corner point;

[0050] Convert the second code value into a decimal system to obtain a corrected vertical coordinate corresponding to the corner point;

[0051] The corrected horizontal coordinate and the corrected vertical coordinate are combined to obtain the corrected coordinate.

[0052] The beneficial effect of this embodiment is that by converting the first coding value and the second coding value into decimal and decoding them to obtain the correction coordinates, it is convenient to correct the projection image later and the correction efficiency can be effectively improved.

[0053] In a second aspect, an embodiment of the present application provides a projection image correction device, comprising:

[0054] A projection module, used to project a picture card in a first feature picture card set onto a projection screen; wherein the first feature picture card set includes at least one pure color picture card, and the picture card projected onto the projection screen covers the projection screen;

[0055] A shooting module, used for shooting the projection screen to obtain a first shot image set;

[0056] Processing modules for:

[0057] Determining image coordinates corresponding to four corner points of the projection screen according to the first captured image set;

[0058] Obtain the color distinction grayscale thresholds corresponding to the four corner points;

[0059] The projection module is further used to project the image cards in the second feature image card set and the third feature image card set onto the projection screen in sequence according to the order in the image card set;

[0060] The shooting module is further used to sequentially shoot the picture cards in the second characteristic picture card set projected on the projection screen to obtain a second shot image set, and sequentially shoot the picture cards in the third characteristic picture card set projected on the projection screen to obtain a third shot image set;

[0061] A correction module is used to correct the projected image according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set.

[0062] The beneficial effects of this embodiment are as follows: by projecting a feature card set including at least one pure color card, and then photographing the projected image, the image coordinates corresponding to the four corner points of the projection screen are determined; and then the color distinction grayscale threshold corresponding to each corner point is obtained. The cards in the second feature card set and the third feature card set are then projected in the order in the card set, and the projected images are photographed in sequence to obtain the second captured image set and the third captured image set, and then the projected image is corrected in combination with the image coordinates corresponding to the four corner points and the color distinction grayscale threshold. Compared with the prior art that is affected by ambient light, this solution adopts the method of first obtaining the color distinction grayscale threshold, and then correcting the projected image in combination with the second captured image set and the third captured image set, so that even under the influence of ambient light, the second captured image set and the third captured image set can be processed according to the color distinction grayscale threshold, thereby realizing image correction of images captured using an ultra-wide-angle lens under the influence of ambient light.

[0063] In a third aspect, an embodiment of the present application provides an ultra-short-throw projection device, comprising:

[0064] A projection host and a projection screen, wherein the projection host includes a processor, a projection unit, and an ultra-wide-angle camera;

[0065] Wherein, the processor is configured to perform the projection image correction method described in any one of the first aspects by executing executable instructions.

[0066] The ultra-short-throw projection device provided in this embodiment can implement the technical solution in the above method embodiment, and its beneficial effects are similar, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the implementation methods in the embodiments of the present application or the related technologies, the following is a brief introduction to the drawings required for use in the embodiments or the related technology descriptions. Obviously, the drawings described below are some embodiments of the present application, and a person skilled in the art can also obtain other drawings based on these drawings.

[0068] Figure 1a Schematic diagram 1 of a trapezoidal projection image provided for this application;

[0069] Figure 1b Schematic diagram of the trapezoidal projection image provided for this application Figure 2 ;

[0070] Figure 1c The feature point image affected by ambient light provided by this application;

[0071] Figure 2 A schematic diagram of an application scenario of the projection image correction method provided in this application;

[0072] Figure 3 A schematic diagram of the structure of the laser projection device provided for this application;

[0073] Figure 4a A schematic diagram of a flow chart of a first embodiment of a projection image correction method provided in the present application;

[0074] Figure 4b A schematic diagram of the sequence of picture cards in the second characteristic picture card set provided by this application;

[0075] Figure 4c A schematic diagram of the sequence of picture cards in the third characteristic picture card set provided by this application;

[0076] Figure 4d A schematic projection diagram of a picture card in the third characteristic picture card set provided by this application;

[0077] Figure 4e A schematic diagram of a picture card in the third characteristic picture card set provided by this application;

[0078] Figure 5 A schematic diagram of the flow chart of the second embodiment of the projection image correction method provided in this application;

[0079] Figure 6 A schematic diagram of the process flow of the third embodiment of the projection image correction method provided in this application;

[0080] Figure 7 This is a schematic structural diagram of an embodiment of the projection image correction device provided in this application. DETAILED DESCRIPTION

[0081] In order to make the purpose, implementation mode and advantages of the present application clearer, the exemplary implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0082] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.

[0083] The terms "first", "second", "third", etc. in the specification and claims of this application and the above drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean to limit a specific order or sequence, unless otherwise noted. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, for example, they can be implemented in an order other than those given in the diagrams or descriptions of the embodiments of this application.

[0084] In addition, the terms "include" and "have" and any variations thereof are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to those components expressly listed but may include other components not expressly listed or inherent to such products or devices.

[0085] With the development of science and technology, people have more choices for viewing equipment. Among them, ultra-short-throw projection equipment such as laser TVs and projectors made with ultra-short-throw lenses are deeply loved by people for their eye protection, bright colors, and power saving.

[0086] Laser projection equipment includes a projection host and a projection screen. When a user uses the laser projection equipment to watch a video or image, the projection host projects the image onto the projection screen and the user can watch it. However, when the projection equipment is used for the first time or the position of the projection host is moved, the image projected by the projection host will be deformed or the projection range will be expanded, so that the projected image cannot completely match the projection screen, affecting the display effect, and the projected image needs to be corrected.

[0087] For example, Figure 1a Schematic diagram of a trapezoidal projection image provided for this application: Figure 1b Schematic diagram of the trapezoidal projection image provided for this application Figure 2 ,like Figure 1a and Figure 1b As shown in the figure, the dotted box represents the projected image, and the solid box represents the projection screen. When the projection device is used for the first time or the position of the projection host is moved, the projected image will be deformed and become a trapezoid, so that the projected image does not match the projection screen.

[0088] In order to correct the projected image, in the prior art, an ultra-short-throw projection device usually projects a picture card with feature points, and the user uses a terminal device with a camera to capture the projected image, thereby identifying the feature points therein, and then determining the correction coordinates for correction.

[0089] The calibration process in the prior art requires the participation of the user and the terminal device, and the process is cumbersome. In order to improve the calibration efficiency, a camera can be installed on the ultra-short-throw projection device to capture the projected image for calibration. However, since the ultra-short-throw projection device is far away from the projection screen, the projection lens used is an ultra-short-throw lens. Therefore, in order to be able to fully capture the projection image, the camera installed on the ultra-short-throw projection device should be an ultra-wide-angle camera to meet the need to capture the entire image on the projection screen.

[0090] However, in order to achieve a better display effect, short-throw projection equipment is usually equipped with a projection screen for image display. The projection screen is generally a Fresnel screen. The light projected by the short-throw projection equipment is incident on the projection screen and then reflected to the human eye, meeting the user's display needs for the projected image. However, the projection screen will also reflect ambient light such as lamplight and strong light. When using an ultra-wide-angle camera to shoot the projection screen, it is also easily affected by the ambient light, resulting in the feature points in the captured projection image being covered by the ambient light and cannot be recognized, and cannot be corrected. For example, Figure 1c The feature point images affected by ambient light provided by this application, such as Figure 1c As shown in the figure, the dotted box represents the projected image, and the solid box represents the projection screen. When the projection device is used for the first time or the position of the projection host is moved, the range of the projected image will become larger, covering the projection screen, and projecting the card with feature points can obtain Figure 1c ,The black dots in the figure represent feature points, which are placed regularly. It can be seen from the figure that there are some feature points in the upper left part that are covered by the ambient light.

[0091] In view of the problems existing in the prior art, the inventor discovered in the process of studying the projection image correction method that in order to enable the ultra-short-focus projection device with an ultra-wide-angle camera to be corrected under the influence of ambient light, the first feature card set including two pure-color cards of different colors is first projected, and then the image coordinates and color-differentiated grayscale thresholds corresponding to the four corner points of the projection screen are photographed and determined. The cards in the second feature card set and the third feature card set are then projected onto the projection screen in sequence according to the order in the card set, and photographed to obtain the second captured image set and the third captured image set. Finally, the projected image is corrected according to the image coordinates and color-differentiated grayscale thresholds corresponding to the four corner points, as well as the second captured image set and the third captured image set, thereby achieving image correction of images captured by an ultra-wide-angle lens under the influence of ambient light and improving the ability to resist environmental interference.

[0092] For example, Figure 2 A schematic diagram of an application scenario of the projection image correction method provided in this application, such as Figure 2As shown, the application scenario may include: a projection host 21 , a projection screen 22 , and an ultra-wide-angle camera 23 installed on the projection host 21 .

[0093] For example, in Figure 2 In the application scenario shown, the user accidentally touches the projection host 21, causing the projection host 21 to move. The user finds that the image projected by the projection host 21 does not match the projection screen, and the projection image needs to be corrected.

[0094] The user fine-tunes the projection host 21 so that the projected image covers the projection screen 22. Then, the projection host 21 can be calibrated. The projection host 21 first projects the cards in the first feature card set onto the projection screen in sequence; during projection, the ultra-wide-angle camera 23 captures the image projected on the projection screen to obtain a first captured image set.

[0095] Then, the image recognition detection is performed on the first captured image set to obtain the image coordinates corresponding to the four corner points of the projection screen, and further, the color distinction grayscale thresholds corresponding to the four corner points can be obtained.

[0096] Then, the image cards in the second feature card set and the third feature card set are sequentially projected onto the projection screen in the order in the card set. During projection, the images projected onto the projection screen are sequentially photographed by the ultra-wide-angle camera 23 to obtain the second captured image set and the third captured image set.

[0097] Then, the projection image is corrected according to the image coordinates corresponding to the four corner points, the color-differentiated grayscale threshold, the second captured image set, and the third captured image set.

[0098] It should be noted that the above scenario is only an example of an application scenario provided by an embodiment of the present application. The embodiment of the present application does not limit the actual form of the various devices included in the scenario, nor does it limit the interaction method between the devices. In the specific application of the solution, it can be set according to actual needs.

[0099] The technical solution of the present application is described in detail below through specific embodiments. It should be noted that the following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0100] Figure 3 The schematic diagram of the structure of the laser projection device provided in this application is as follows: Figure 3As shown, the laser projection device includes a projection host 31 and a projection screen 32. The projection host 31 includes a processor 33, a projection unit 34 connected to the processor 33, and an ultra-wide-angle camera 35. The processor 33 can project an image onto the projection screen 32 through the projection unit 34, and can also shoot the image projected onto the projection screen 32 through the ultra-wide-angle camera 35. The projection unit 34 is composed of a light source component, a light modulation component, and a lens. The light source component is composed of a light emitting device, a lens, etc., wherein the light emitting device can be a full three-color laser or a laser with a color wheel. The light modulation component modulates the light output by the light source according to the image display information. The lens projects the modulated light onto the projection screen 32.

[0101] Figure 4a The flowchart of the first embodiment of the projection image correction method provided by the present application is a flowchart of the first embodiment of the projection image correction method provided by the present application. The execution subject of the method is an ultra-short-throw projection device. The present application embodiment first projects the first feature image card set on the ultra-short-throw projection device and shoots it. After determining the image coordinates corresponding to the four corner points of the projection screen, the color-differentiated grayscale threshold is obtained. Then, the second feature image card set and the third feature image card set are projected and shot. After obtaining the shot image, the projection image is corrected in combination with the image coordinates and the color-differentiated grayscale threshold. The method in the present embodiment can be implemented by software, hardware, or a combination of software and hardware. Figure 4a As shown, the projection image correction method specifically includes the following steps:

[0102] S401: Projecting a card in a first feature card set onto a projection screen, photographing the projection screen to obtain a first photographed image set, and determining image coordinates corresponding to four corner points of the projection screen according to the first photographed image set.

[0103] When the projection image needs to be corrected, the user first fine-tunes the projection host so that the projected image can cover the projection screen, and then the user can control the projection host to start correcting the projection image.

[0104] In this step, in order to calibrate the projected image, the ultra-short-throw projection device needs to first project the cards in the first feature card set onto the projection screen in sequence through the projection unit. The first feature card set includes at least one pure color card, and the card projected onto the projection screen covers the projection screen.

[0105] It should be noted that if the first feature card set includes only one pure color card, the grayscale value of the pure color card can be 255, 230, 200, 150, etc. In this embodiment of the application, you do not limit the grayscale value of the pure color card and can set it according to actual conditions.

[0106] After the ultra-short-throw projection device projects the image cards in the first feature image card set onto the projection screen through the projection unit, the image projected on the projection screen can be photographed by the ultra-wide-angle camera to obtain a first photographed image set.

[0107] Then, an image in the first captured image set is identified and detected to determine the image coordinates corresponding to the four corner points of the projection screen.

[0108] S402: Obtain color distinction grayscale thresholds corresponding to four corner points.

[0109] In this step, after the ultra-short-throw projection device obtains the image coordinates corresponding to the four corner points, in order to subsequently correct the projected image, it is also necessary to obtain the color distinction grayscale thresholds corresponding to the four corner points.

[0110] In one implementation, the first feature image card set includes at least two pure color image cards with different grayscale values; then, each image in the first captured image set is grayscale converted to obtain at least two second grayscale images.

[0111] Then, based on the image coordinates corresponding to the four corner points and each second grayscale image, determine at least two grayscale values ​​corresponding to each of the four corner points; for each corner point, based on the image coordinates corresponding to the corner point, determine the grayscale value of the pixel point at the image coordinates in each second grayscale image, which is the at least two grayscale values ​​corresponding to the corner point.

[0112] Furthermore, for each of the four corner points, an average value of at least two grayscale values ​​corresponding to the corner point is determined as the color distinction grayscale threshold corresponding to the corner point.

[0113] It should be noted that the grayscale value of the pure color image card in the first feature image card set can be 255, 230, 200, 150, 130, 100, 50, 0, etc. The embodiment of the present application does not limit the grayscale value of the pure color image card in the first feature image card set, and can be determined according to actual conditions.

[0114] In another implementation manner, for each of the four corner points, a preset grayscale threshold corresponding to the corner point that is stored may be obtained as the color distinction grayscale threshold corresponding to the corner point.

[0115] S403: Project the cards in the second feature card set and the third feature card set onto the projection screen in sequence according to the order in the card set; and photograph the cards in the second feature card set projected on the projection screen in sequence to obtain a second captured image set, and photograph the cards in the third feature card set projected on the projection screen in sequence to obtain a third captured image set.

[0116] In this step, after the ultra-short-throw projection device obtains the image coordinates and color distinction grayscale thresholds corresponding to the four corner points of the projection screen, it is also necessary to use the projection unit to project the cards in the second feature card set and the third feature card set in the order in the card set onto the projection screen in sequence, and the projected image will cover the projection screen.

[0117] For the second characteristic card set and the third characteristic card set, the cards therein are in order and are projected in sequence.

[0118] It should be noted that, each card in the second feature card set is a card with vertical first stripes and vertical second stripes placed alternately, the grayscale value of the first stripe in each card in the second feature card set is the same, the stripe width in the first card in the second feature card set is the first preset width, for each card in the second feature card set except the first card, the stripe width in the card is half of the stripe width in the previous card, and the grayscale values ​​of the first stripe and the second stripe are different.

[0119] Each card in the third feature card set is a card with horizontal third stripes and horizontal fourth stripes placed alternately, the grayscale value of the first stripe in each card in the third feature card set is the same, the stripe width in the first card in the third feature card set is the second preset width, for each card in the third feature card set except the first card, the stripe width in the card is half of the stripe width in the previous card, and the grayscale values ​​of the third stripe and the fourth stripe are different.

[0120] It should be noted that the grayscale values ​​of the first stripe and the third stripe can be 0, 10, 30, etc., and the grayscale values ​​of the second stripe and the fourth stripe can be 255, 240, 230, etc. The embodiment of the present application does not limit the grayscale values ​​of the first stripe, the second stripe, the third stripe, and the fourth stripe, and can be set according to actual conditions.

[0121] It should be noted that the first preset width is 1 / 2, 1 / 4, 1 / 8, etc. of the horizontal length of the first card in the second characteristic card set; the second preset width is 1 / 2, 1 / 4, 1 / 8, etc. of the vertical length of the first card in the third characteristic card set. The first stripe in the card in the second characteristic card set refers to the first stripe of all stripes in the card from left to right. The first stripe in the card in the third characteristic card set refers to the first stripe of all stripes in the card from top to bottom.

[0122] For example, Figure 4b A schematic diagram of the sequence of picture cards in the second feature picture card set provided by this application, such as Figure 4bAs shown, the second feature card set includes four cards, and the stripes in each card are vertical stripes with a grayscale value of 0 and vertical stripes with a grayscale value of 255, which are placed alternately. The grayscale value of the first stripe in each card in the second feature card set is the same, and the stripe width in the first card is half of the horizontal length of the first card. For the second to fourth cards, the stripe width in each card is half of the stripe width in the previous card. The embodiment of the present application does not limit the number of cards in the second feature card set, and can be determined according to actual conditions.

[0123] Figure 4c A schematic diagram of the sequence of the image cards in the third characteristic image card set provided by this application, such as Figure 4c As shown, the third feature card set includes four cards, and the stripes in each card are horizontal stripes with a grayscale value of 0 and horizontal stripes with a grayscale value of 255, which are placed alternately. The grayscale value of the first stripe in each card in the third feature card set is the same, and the stripe width in the first card is half of the width of the first card. For the second to fourth cards, the stripe width in each card is half of the stripe width in the previous card. The embodiment of the present application does not limit the number of cards in the third feature card set, and it can be determined according to actual conditions.

[0124] For example, Figure 4d This is a schematic diagram of the projection of the image card in the third feature image card set provided by this application. Figure 4d As shown, the black box in the figure represents the projection screen, and the picture cards in the third feature picture card set are projected onto the projection screen, and the projected image can cover the projection screen.

[0125] It should be noted that the cards in the second feature card set and the third feature card set may have stripes with two different gray values ​​alternately placed near the four vertices. Figure 4e A schematic diagram of a picture card in the third characteristic picture card set provided by this application, such as Figure 4e As shown in the figure, stripes with grayscale values ​​of 0 and 255 are placed alternately at the four vertices. Figure 4c The image card in the figure is processed by retaining only the stripes at the four vertices, and we can get Figure 4e This is an image in which stripes with grayscale values ​​of 0 and 255 are placed alternately at only four vertices.

[0126] It should be noted that if the first feature card set includes only two pure color cards, the grayscale value of the first stripe and the grayscale value of the third stripe in the cards of the second feature card set and the third feature card set can be the same as the grayscale value of a pure color card in the first feature card set, and the grayscale value of the second stripe and the grayscale value of the fourth stripe can be the same as the grayscale value of another pure color card in the first feature card set.

[0127] It should be noted that the order of projecting the second feature map card set and the third feature map card set can be to project the second feature map card set first and then the third feature map card set; or to project the third feature map card set first and then the third feature map card set. The embodiment of the present application does not limit the order of projecting the second feature map card set and the third feature map card set, which can be determined according to actual conditions.

[0128] For each image card in the second feature image card set, after the image card is projected onto the projection screen in sequence by the projection unit, the image projected on the projection screen can be photographed by the ultra-wide-angle camera; after each image card in the second feature image card set is projected and photographed, a second captured image set can be obtained.

[0129] For each image card in the third feature image card set, after the image card is projected onto the projection screen in sequence through the projection unit, the image projected on the projection screen can be photographed by the ultra-wide-angle camera; after each image card in the third feature image card set is projected and photographed, the third captured image set can be obtained.

[0130] Since the images in the second captured image set are obtained by capturing the images in the projected second feature picture card set, an image is captured and stored in the second captured image set in the order of capturing. Therefore, there is a one-to-one correspondence between the images in the second captured image set and the picture cards in the second feature picture card set. The position of the image in the second captured image set is the same as the position of the picture card corresponding to the image in the second feature picture card set; similarly, the position of the image in the third captured image set is the same as the position of the picture card corresponding to the image in the third feature picture card set.

[0131] S404: Correcting the projected image according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set.

[0132] In this step, after obtaining the second captured image set and the third captured image set, the ultra-short focus projection device can determine the correction coordinates corresponding to the four corner points based on the image coordinates corresponding to the four corner points and the color-distinguishing grayscale threshold, as well as the second captured image set and the third captured image set.

[0133] For each corner point, the grayscale value of the corner point in each image in the second captured image set is determined according to the image coordinates corresponding to the corner point, and then the first coding value corresponding to the corner point is obtained by combining the color-differentiated grayscale threshold, and then the second coding value corresponding to the corner point is decoded to obtain the corrected horizontal coordinate corresponding to the corner point. According to the image coordinates corresponding to the corner point, the grayscale value of the corner point in each image in the third captured image set is determined, and then the second coding value corresponding to the corner point is decoded to obtain the corrected vertical coordinate corresponding to the corner point, and then the corrected horizontal coordinate and the corrected vertical coordinate are combined to obtain the corrected coordinate.

[0134] After the correction coordinates are obtained, the projected image can be corrected according to the correction coordinates corresponding to the four corner points.

[0135] Specifically, the image correction can be achieved by adjusting the four vertices of the projected image to the positions of the correction horizontal coordinates and correction vertical coordinates corresponding to the four corner points. For the vertex in the upper left corner, move it down by the correction vertical coordinate units corresponding to the upper left corner point, and then move it right by the correction horizontal coordinate units corresponding to the upper left corner point; for the vertex in the upper right corner, move it down by the correction vertical coordinate units corresponding to the upper right corner point, and then move it left by the correction horizontal coordinate units corresponding to the upper right corner point; for the vertex in the lower left corner, move it up by the correction vertical coordinate units corresponding to the lower left corner point, and then move it right by the correction horizontal coordinate units corresponding to the lower left corner point; for the vertex in the lower right corner, move it up by the correction vertical coordinate units corresponding to the lower right corner point, and then move it left by the correction horizontal coordinate units corresponding to the lower right corner point.

[0136] The projection image correction method provided in this embodiment projects the image cards in the first feature image card set onto the projection screen, and photographs the projection screen to obtain the first captured image set, and then determines the image coordinates corresponding to the four corner points of the projection screen according to the first captured image set to obtain the color distinction grayscale threshold. The image cards in the second feature image card set and the third feature image card set are then projected onto the projection screen in sequence, and photographed in sequence to obtain the second captured image set and the third captured image set. Finally, the projection image is corrected according to the image coordinates corresponding to the four corner points and the color distinction grayscale threshold, as well as the second captured image set and the third captured image set. This allows the second captured image set and the third captured image set to be processed according to the color distinction grayscale threshold even under the influence of ambient light, thereby realizing image correction of images captured using an ultra-wide-angle lens under the influence of ambient light.

[0137] Figure 5 This is a flow chart of the second embodiment of the projection image correction method provided by the present application. Based on the above embodiment, the present embodiment of the present application describes the situation where the ultra-short-throw projection device determines the image coordinates corresponding to the four corner points of the projection screen according to the first captured image set. Figure 5As shown, the projection image correction method specifically includes the following steps:

[0138] S501: Perform grayscale conversion on any one of the captured images in the first captured image set to obtain a first grayscale image.

[0139] In this step, after the ultra-short-throw projection device obtains the first captured image set, since the first captured image set includes at least one image, any captured image in the first captured image set can be used to determine the image coordinates corresponding to the four corner points. First, grayscale conversion is performed on any captured image in the first captured image set to obtain a first grayscale image.

[0140] It should be noted that the grayscale conversion may be performed on the image whose frame of the projection screen is more easily identifiable and included in the first captured image set.

[0141] S502: Perform edge detection on the first grayscale image to determine image coordinates corresponding to four corner points of the projection screen.

[0142] In this step, after obtaining the first grayscale image, the ultra-short-throw projection device performs edge detection on it to determine the position of the border of the projection screen in the first grayscale image, and then determine the image coordinates corresponding to the four corner points of the projection screen.

[0143] Specifically, after edge detection is performed on the first grayscale image, multiple edges can be obtained, and closed edges among them are determined, and then the edge with the largest area is removed from all closed edges. The edge is the edge of the projected image, and then the edge located in the set position range is determined, and the edge of the projection screen can be obtained, and then the image coordinates corresponding to the four corner points can be determined. The image coordinate system takes the upper left corner of the first grayscale image as the origin, the right direction is the square of the horizontal axis, and the bottom direction is the positive direction of the vertical axis.

[0144] It should be noted that after obtaining the first grayscale image, it can be subjected to denoising before edge detection, which can effectively improve the accuracy of the image coordinates corresponding to the four corner points. The denoising method can be a weighted average method, a Gaussian filter method, a median filter method, a bilateral filter method, etc. The embodiment of the present application does not limit the denoising method, which can be determined according to actual conditions.

[0145] The projection image correction method provided in this embodiment performs grayscale conversion on the image in the first captured image and then performs edge detection to obtain image coordinates corresponding to the four corner points of the projection screen, thereby effectively improving the accuracy of the image coordinates of the obtained corner points.

[0146] Figure 6This is a flow chart of the third embodiment of the projection image correction method provided by the present application. Based on the above embodiment, the present embodiment of the present application describes the situation in which the ultra-short-throw projection device determines the correction coordinates corresponding to the four corner points according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set. Figure 6 As shown, the projection image correction method specifically includes the following steps:

[0147] S601: For each of the four corner points, determine, according to the image coordinates corresponding to the corner point, a first grayscale value of the corner point in each image in the second captured image set and a second grayscale value of the corner point in each image in the third captured image set.

[0148] In this step, after the ultra-short focus projection device obtains the image coordinates and color distinction grayscale thresholds corresponding to the four corner points, as well as the second captured image set and the third captured image set, for each of the four corner points, based on the image coordinates corresponding to the corner point, the first grayscale value of the corner point in each image in the second captured image set and the second grayscale value of the corner point in each image in the third captured image set are determined.

[0149] According to the image coordinates corresponding to the corner point, the RGB value of the pixel point at the image coordinate in each image in the second captured image set is determined, and then converted into a grayscale value, which is the first grayscale value of the corner point in each image in the second captured image set. According to the image coordinates corresponding to the corner point, the RGB value of the pixel point at the image coordinate in each image in the third captured image set is determined, and then converted into a grayscale value, which is the second grayscale value of the corner point in each image in the third captured image set.

[0150] It should be noted that each image in the second captured image set can be converted into a grayscale image, and the grayscale value of the pixel point at the image coordinate position can be determined, which is the first grayscale value of the corner point in each image in the second captured image set. Each image in the third captured image set can be converted into a grayscale image, and the grayscale value of the pixel point at the image coordinate position can be determined, which is the second grayscale value of the corner point in each image in the third captured image set.

[0151] S602: Distinguish the grayscale threshold according to the first grayscale value and the color corresponding to the corner point, and determine the first coding value corresponding to the corner point.

[0152] In this step, after obtaining the first grayscale value, the ultra-short-throw projection device can distinguish the grayscale threshold according to the first grayscale value and the color corresponding to the corner point, and determine the first coding value corresponding to the corner point.

[0153] Specifically, for each image in the second captured image set, if the first grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, the first sub-code value corresponding to the image is determined to be 1; if the first grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the first sub-code value corresponding to the image is determined to be 0;

[0154] Then, according to the arrangement order of each image in the second captured image set, the first sub-coding value corresponding to each image is sorted to obtain the first coding value corresponding to the corner point.

[0155] It should be noted that since the first stripes of the first few images in the second feature card set are wider, the corner points of the upper left corner and the lower left corner are within the first stripe, and when the grayscale value of the first stripe is 255, the first sub-coding values ​​corresponding to the corner points of the upper left corner and the lower left corner in the first few images are all 1, and the first sub-coding values ​​corresponding to the corner points of the upper right corner and the lower right corner in the first few images are all 0. Therefore, it is not necessary to shoot the projections of the first preset number of images in the second feature card set and determine the first sub-coding values ​​based on the shot images; the first sub-coding values ​​corresponding to the corner points of the upper left corner and the lower left corner in the first preset number of images are set to 1, and the first sub-coding values ​​corresponding to the corner points of the upper right corner and the lower right corner in the first preset number of images are set to 0.

[0156] When the gray value of the first stripe is 0, the first sub-code value corresponding to the first preset number of images of the upper left corner and the lower left corner is set to 0, and the first sub-code value corresponding to the first preset number of images of the upper right corner and the lower right corner is set to 1. This reduces the amount of calculation and improves efficiency. The preset number can be 2, 3, 4, etc. The embodiment of the present application does not limit the preset number, and it can be set according to actual conditions.

[0157] It should be noted that if the grayscale value of the first stripe in each image in the second feature image card set is 0, the 0 in the first coding value is replaced by 1, and the 1 is replaced by 0 to obtain an updated first coding value; if the grayscale value of the first stripe in each image in the second feature image card set is 255, there is no need to process the first coding value.

[0158] S603: Distinguish the grayscale threshold according to the second grayscale value and the color corresponding to the corner point, and determine the second coding value corresponding to the corner point.

[0159] In this step, after obtaining the second grayscale value, the ultra-short-throw projection device can distinguish the grayscale threshold according to the second grayscale value and the color corresponding to the corner point, and determine the second coding value corresponding to the corner point.

[0160] Specifically, for each image in the third captured image set, if the second grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, the second sub-coding value corresponding to the image is determined to be 1; if the second grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the second sub-coding value corresponding to the image is determined to be 0.

[0161] Then, according to the arrangement order of each image in the third captured image set, the second sub-coded value corresponding to each image is sorted to obtain the second coded value corresponding to the corner point.

[0162] It should be noted that since the first stripes of the first few images in the third feature card set are wider, the corner points of the upper left corner and the upper right corner are within the first stripe, when the grayscale value of the first stripe is 255, the first sub-coding values ​​corresponding to the corner points of the upper left corner and the upper right corner in the first few images are all 1, and the first sub-coding values ​​corresponding to the corner points of the lower left corner and the lower right corner in the first few images are all 0. Therefore, it is not necessary to shoot the projections of the first preset number of images in the third feature card set and determine the second sub-coding value based on the shot image; the second sub-coding values ​​corresponding to the corner points of the upper left corner and the upper right corner in the first preset number of images are set to 1, and the second sub-coding values ​​corresponding to the corner points of the lower left corner and the lower right corner in the first preset number of images are set to 0.

[0163] When the gray value of the first stripe is 0, the second sub-code value corresponding to the preset number of images of the upper left corner and the upper right corner is set to 0, and the second sub-code value corresponding to the preset number of images of the lower left corner and the lower right corner is set to 1. This reduces the amount of calculation and improves efficiency. The preset number can be 2, 3, 4, etc. The embodiment of the present application does not limit the preset number, and it can be set according to actual conditions.

[0164] It should be noted that if the grayscale value of the first stripe in each image in the third feature card set is 0, then the 0 in the second coding value is replaced by 1, and the 1 is replaced by 0 to obtain an updated second coding value; if the grayscale value of the first stripe in each image in the third feature card set is 255, there is no need to process the second coding value.

[0165] It should be noted that the execution order of step S602 and step S603 can be step S602 first and then step S603; or step S603 first and then step S602; or step S602 and step S603 can be executed simultaneously. The embodiment of the present application does not limit the execution order of step S602 and step S603, and can be set according to actual conditions.

[0166] S604: Decode the first coded value and the second coded value to obtain the corrected coordinates corresponding to the corner point.

[0167] In this step, after obtaining the first coding value, the ultra-short-throw projection device can decode the first coding value to obtain the corrected horizontal coordinate corresponding to the corner point.

[0168] Specifically, the first code value is converted into a decimal system to obtain the corrected horizontal coordinate corresponding to the corner point.

[0169] Exemplarily, the first coding value is 00011001100, which is converted into decimal to obtain 408, which is the corrected horizontal coordinate.

[0170] After obtaining the second coding value, the ultra-short-throw projection device can decode the second coding value to obtain the corrected vertical coordinate corresponding to the corner point.

[0171] Specifically, the second code value is converted into a decimal system to obtain the corrected vertical coordinate corresponding to the corner point.

[0172] Then, the corrected horizontal coordinate and the corrected vertical coordinate are combined to obtain the corrected coordinate.

[0173] The projection image correction method provided in this embodiment determines the first coding value and the second coding value corresponding to the corner point through the first gray value of the corner point in each image in the second captured image set, the second gray value of the corner point in each image in the third captured image set, and the color-differentiated gray threshold corresponding to the corner point, and then decodes them to obtain the corrected horizontal coordinate and the corrected vertical coordinate, so that the corrected horizontal coordinate and the corrected vertical coordinate are more accurate. Then, the corrected horizontal coordinate and the corrected vertical coordinate are used to correct the projection image, which can effectively improve the accuracy of the correction and improve the display effect. In addition, the color-differentiated gray threshold is used to determine the first coding value and the second coding value corresponding to the corner point, so that the determined coding value is not affected by ambient light.

[0174] Figure 7 This is a schematic diagram of the structure of an embodiment of the projection image correction device provided by the present application; the device can be integrated into the ultra-short-throw projection device in the above method embodiment, or can be implemented by the ultra-short-throw projection device in the above method embodiment. Figure 7 As shown, the projection image correction device 70 includes:

[0175] The projection module 71 is used to project the image cards in the first characteristic image card set onto the projection screen; wherein the first characteristic image card set includes at least one pure color image card, and the image cards projected onto the projection screen cover the projection screen;

[0176] A shooting module 72, used for shooting the projection screen to obtain a first shot image set;

[0177] The processing module 73 is used to:

[0178] Determining image coordinates corresponding to four corner points of the projection screen according to the first captured image set;

[0179] Obtain the color distinction grayscale thresholds corresponding to the four corner points;

[0180] The projection module 71 is further used to project the image cards in the second feature image card set and the third feature image card set onto the projection screen in sequence according to the order in the image card set;

[0181] The shooting module 72 is further used to sequentially shoot the picture cards in the second characteristic picture card set projected on the projection screen to obtain a second captured image set, and sequentially shoot the picture cards in the third characteristic picture card set projected on the projection screen to obtain a third captured image set;

[0182] The correction module 74 is used to correct the projection image according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set.

[0183] Furthermore, the processing module 73 is specifically used for:

[0184] Performing grayscale conversion on any one of the first captured images to obtain a first grayscale image;

[0185] Perform edge detection on the first grayscale image to determine image coordinates corresponding to four corner points of the projection screen.

[0186] Furthermore, the first feature image card set includes at least two pure color image cards with different grayscale values, and the processing module 73 is specifically used to

[0187] Performing grayscale conversion on each image in the first captured image set to obtain at least two second grayscale images;

[0188] Determine at least two grayscale values ​​corresponding to each of the four corner points according to the image coordinates corresponding to the four corner points and each second grayscale image;

[0189] For each of the four corner points, an average value of at least two grayscale values ​​corresponding to the corner point is determined as a color distinguishing grayscale threshold corresponding to the corner point.

[0190] Furthermore, the processing module 73 is specifically used for:

[0191] For each of the four corner points, a preset grayscale threshold corresponding to the stored corner point is obtained as the color distinguishing grayscale threshold corresponding to the corner point.

[0192] Further, each image card in the second characteristic image card set is an image card in which vertical first stripes and vertical second stripes are alternately placed, the grayscale value of the first stripes in each image card in the second characteristic image card set is the same, the width of the stripes in the first image card in the second characteristic image card set is a first preset width, for each image card in the second characteristic image card set except the first image card, the width of the stripes in the image card is half of the width of the stripes in the previous image card of the image card, and the grayscale value of the first stripes is different from that of the second stripes;

[0193] Each card in the third characteristic card set is a card in which horizontal third stripes and horizontal fourth stripes are placed alternately, the grayscale value of the first stripe in each card in the third characteristic card set is the same, the stripe width in the first card in the third characteristic card set is the second preset width, for each card in the third characteristic card set except the first card, the stripe width in the card is half of the stripe width in the previous card of the card, and the grayscale value of the third stripe is different from that of the fourth stripe.

[0194] Furthermore, the correction module 74 is specifically used for:

[0195] Determine the correction coordinates corresponding to the four corner points according to the image coordinates corresponding to the four corner points and the color distinction grayscale threshold, as well as the second captured image set and the third captured image set;

[0196] The projection image is corrected according to the correction coordinates corresponding to the four corner points.

[0197] Furthermore, the correction module 74 is specifically used for:

[0198] For each of the four corner points, determining, according to the image coordinates corresponding to the corner point, a first grayscale value of the corner point in each image in the second captured image set, and a second grayscale value of the corner point in each image in the third captured image set;

[0199] Determine a first coding value corresponding to the corner point according to the first gray value and a color-differentiated gray threshold corresponding to the corner point;

[0200] Determine a second encoding value corresponding to the corner point according to the second grayscale value and a color-distinguishing grayscale threshold corresponding to the corner point;

[0201] The first coding value and the second coding value are decoded to obtain the corrected coordinates corresponding to the corner point.

[0202] Furthermore, the correction module 74 is specifically used for:

[0203] For each image in the second captured image set, if the first grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, then determining the first sub-code corresponding to the image to be 1;

[0204] If the first grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the first subcode corresponding to the image is determined to be 0;

[0205] According to the arrangement order of each image in the second captured image set, the first sub-code corresponding to each image is sorted to obtain the first code value corresponding to the corner point.

[0206] Furthermore, the correction module 74 is specifically used for:

[0207] For each image in the third captured image set, if the second grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, then determining the second sub-code corresponding to the image to be 1;

[0208] If the second grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the second sub-code corresponding to the image is determined to be 0;

[0209] According to the arrangement order of each image in the third captured image set, the second sub-code corresponding to each image is sorted to obtain the second code value corresponding to the corner point.

[0210] Furthermore, the correction module 74 is specifically used for:

[0211] Convert the first code value into a decimal system to obtain a corrected horizontal coordinate corresponding to the corner point;

[0212] Convert the second code value into a decimal system to obtain a corrected vertical coordinate corresponding to the corner point;

[0213] The corrected horizontal coordinate and the corrected vertical coordinate are combined to obtain the corrected coordinate.

[0214] The projection image correction device provided in this embodiment is used to execute the technical solution in any of the aforementioned embodiments. Its implementation principle and technical effects are similar and will not be described in detail here.

[0215] The following is an ultra-short-throw projection device provided by the present application. The ultra-short-throw projection device includes:

[0216] Processor, memory, communication interface, projection unit, ultra-wide-angle camera, projection screen;

[0217] The memory is used to store executable instructions of the processor;

[0218] Among them, the processor is configured to execute the technical solution in any of the aforementioned method embodiments by executing the executable instructions.

[0219] Optionally, the memory can be either independent or integrated with the processor.

[0220] Optionally, when the memory is a device independent of the processor, the ultra-short-throw projection device may further include:

[0221] The projection unit, the ultra-wide-angle camera, the memory and the communication interface are connected to the processor through the bus and communicate with each other. The communication interface is used to communicate with other devices.

[0222] Optionally, the communication interface can be implemented by a transceiver. The communication interface is used to implement communication between the database access device and other devices (such as a client, a read-write library, and a read-only library). The memory may include a random access memory (RAM) and may also include a non-volatile memory (non-volatile memory), such as at least one disk storage.

[0223] The bus can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0224] The above-mentioned processor can be a general-purpose processor, including a central processing unit CPU, a network processor (NP), etc.; it can also be a digital signal processor DSP, an application-specific integrated circuit ASIC, a field programmable gate array FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0225] The ultra-short-throw projection device is used to execute the technical solution in any of the aforementioned method embodiments, and its implementation principle and technical effect are similar and will not be repeated here.

[0226] An embodiment of the present application also provides a readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the technical solution provided by any of the aforementioned method embodiments is implemented.

[0227] An embodiment of the present application also provides a computer program product, including a computer program, which is used to implement the technical solution provided by any of the aforementioned method embodiments when executed by a processor.

[0228] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0229] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0230] For the convenience of explanation, the above description has been made in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or limit the embodiments to the specific forms disclosed above. Based on the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are to better explain the principles and practical applications, so that those skilled in the art can better use the embodiments and various different variations of the embodiments suitable for specific use considerations.

Claims

1. A projection image correction method, characterized in that: Applied to an ultra-short-throw projection device, the ultra-short-throw projection device includes a projection host and a projection screen, the projection host includes a projection unit and an ultra-wide-angle camera, and the method includes: Projecting a card in a first feature card set onto the projection screen, photographing the projection screen to obtain a first captured image set, and determining image coordinates corresponding to four corner points of the projection screen according to the first captured image set; wherein the first feature card set includes at least one pure color card, and the card projected onto the projection screen covers the projection screen; Obtain the color distinction grayscale thresholds corresponding to the four corner points; The cards in the second feature card set and the third feature card set are sequentially projected onto the projection screen in the order in the card set; the cards in the second feature card set projected onto the projection screen are sequentially photographed to obtain a second captured image set, and the cards in the third feature card set projected onto the projection screen are sequentially photographed to obtain a third captured image set; The projection image is corrected according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set.

2. The method according to claim 1, characterized in that The step of determining the image coordinates corresponding to the four corner points of the projection screen according to the first captured image set includes: Performing grayscale conversion on any one of the first captured images to obtain a first grayscale image; Perform edge detection on the first grayscale image to determine image coordinates corresponding to four corner points of the projection screen.

3. The method according to claim 1, characterized in that The first feature image card set includes at least two pure color image cards with different grayscale values; The obtaining of the color distinction grayscale thresholds corresponding to the four corner points includes: Performing grayscale conversion on each image in the first captured image set to obtain at least two second grayscale images; Determine at least two grayscale values ​​corresponding to each of the four corner points according to the image coordinates corresponding to the four corner points and each second grayscale image; For each of the four corner points, an average value of at least two grayscale values ​​corresponding to the corner point is determined as a color distinguishing grayscale threshold corresponding to the corner point.

4. The method according to claim 1, characterized in that: The obtaining of the color distinction grayscale thresholds corresponding to the four corner points includes: For each of the four corner points, a preset grayscale threshold corresponding to the stored corner point is obtained as the color distinguishing grayscale threshold corresponding to the corner point.

5. The method according to claim 1, characterized in that Each image card in the second characteristic image card set is an image card in which vertical first stripes and vertical second stripes are placed alternately, the grayscale value of the first stripes in each image card in the second characteristic image card set is the same, the width of the stripes in the first image card in the second characteristic image card set is a first preset width, for each image card in the second characteristic image card set except the first image card, the width of the stripes in the image card is half of the width of the stripes in the previous image card, and the grayscale values ​​of the first stripes and the second stripes are different; Each card in the third characteristic card set is a card in which horizontal third stripes and horizontal fourth stripes are placed alternately, the grayscale value of the first stripe in each card in the third characteristic card set is the same, the stripe width in the first card in the third characteristic card set is the second preset width, for each card in the third characteristic card set except the first card, the stripe width in the card is half of the stripe width in the previous card of the card, and the grayscale value of the third stripe is different from that of the fourth stripe.

6. The method according to claim 1, characterized in that The method of correcting the projected image according to the image coordinates and color-differentiated grayscale thresholds corresponding to the four corner points, and the second captured image set and the third captured image set includes: Determine the correction coordinates corresponding to the four corner points according to the image coordinates corresponding to the four corner points and the color distinction grayscale threshold, as well as the second captured image set and the third captured image set; The projection image is corrected according to the correction coordinates corresponding to the four corner points.

7. The method according to claim 6, characterized in that The step of determining the correction coordinates corresponding to the four corner points according to the image coordinates corresponding to the four corner points and the color-differentiated grayscale threshold, as well as the second captured image set and the third captured image set, comprises: For each of the four corner points, determining, according to the image coordinates corresponding to the corner point, a first grayscale value of the corner point in each image in the second captured image set, and a second grayscale value of the corner point in each image in the third captured image set; Determine a first coding value corresponding to the corner point according to the first gray value and a color-differentiated gray threshold corresponding to the corner point; Determine a second encoding value corresponding to the corner point according to the second grayscale value and a color-differentiated grayscale threshold corresponding to the corner point; The first coding value and the second coding value are decoded to obtain the corrected coordinates corresponding to the corner point.

8. The method according to claim 7, characterized in that The determining the first coding value corresponding to the corner point according to the first gray value and the color corresponding to the corner point to distinguish the gray threshold comprises: For each image in the second captured image set, if the first grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, then determining the first sub-code corresponding to the image to be 1; If the first grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the first subcode corresponding to the image is determined to be 0; According to the arrangement order of each image in the second captured image set, the first sub-code corresponding to each image is sorted to obtain the first code value corresponding to the corner point.

9. The method according to claim 7, characterized in that: The determining the second encoding value corresponding to the corner point according to the second gray value and the color corresponding to the corner point to distinguish the gray threshold comprises: For each image in the third captured image set, if the second grayscale value of the corner point in the image is greater than the color distinction grayscale threshold corresponding to the corner point, then determining the second sub-code corresponding to the image to be 1; If the second grayscale value of the corner point in the image is less than or equal to the color distinction grayscale threshold corresponding to the corner point, the second sub-code corresponding to the image is determined to be 0; According to the arrangement order of each image in the third captured image set, the second sub-code corresponding to each image is sorted to obtain the second code value corresponding to the corner point.

10. The method according to claim 7, characterized in that The decoding of the first coded value and the second coded value to obtain the corrected coordinates corresponding to the corner point includes: Convert the first code value into a decimal system to obtain a corrected horizontal coordinate corresponding to the corner point; Convert the second code value into a decimal system to obtain a corrected vertical coordinate corresponding to the corner point; The corrected horizontal coordinate and the corrected vertical coordinate are combined to obtain the corrected coordinate.

Images