Picture encryption system and picture encryption method

Abstract

A picture encryption system and a picture encryption method. The picture encryption system includes a memory and a processor. The memory is used to store a plurality of instructions. The processor is used to execute the following steps according to the plurality of instructions of the memory: adding a text string to a region in a picture, and the text string includes a high gray level text string and a low gray level text string; in a time interval, obtaining an encryption high gray level of the high gray level text string and an encryption low gray level of the low gray level text string; and when the average value is equal to the display gray level of the picture, outputting the picture and the text string.

Description

Technical Field

[0001] This disclosure relates to an encryption system and encryption method, and particularly to a screen encryption system and screen encryption method. Background Technology

[0002] Currently, in order to protect the privacy of images, watermarks or text strings are often added to the images. However, watermarks or text strings can hinder the viewing or reading of viewers or readers. Summary of the Invention

[0003] This summary is intended to provide a simplified overview of the present disclosure to enable the reader to gain a basic understanding of it. It is not a complete summary of the present disclosure and is not intended to identify key / critical elements of the embodiments or define the scope of the disclosure.

[0004] One embodiment of this disclosure relates to a screen encryption system. The screen encryption system includes a memory and a processor. The memory stores multiple instructions. The processor executes the following steps according to the multiple instructions from the memory: adding a text string to a region of the screen, wherein the text string includes a high-grayscale text string and a low-grayscale text string; obtaining, within a time interval, the average value of the encrypted high-grayscale of the high-grayscale text string and the encrypted low-grayscale of the low-grayscale text string; and outputting the screen and the text string when the average value equals the display grayscale of the screen.

[0005] Another technical embodiment of this disclosure relates to a screen encryption method. The screen encryption method includes the following steps: adding a text string to a region of the screen, wherein the text string includes a high grayscale text string and a low grayscale text string; obtaining the average value of the encrypted high grayscale of the high grayscale text string and the encrypted low grayscale of the low grayscale text string within a time interval; and outputting the screen and the text string when the average value is equal to the display grayscale of the screen.

[0006] Therefore, according to the technical content of this disclosure, the image encryption system and image encryption method shown in the embodiments of this disclosure can achieve the effect that the text string cannot be seen by the human eye, but can be captured by the camera when shooting.

[0007] After reading the following embodiments, those skilled in the art to which this disclosure pertains will easily understand the basic concept and other inventive objectives of this disclosure, as well as the technical means and implementation methods adopted in this disclosure. Attached Figure Description

[0008] To make the above and other objects, features, advantages and embodiments of this disclosure more apparent and understandable, the accompanying drawings are described below:

[0009] Figure 1This is a block diagram illustrating a screen encryption system according to an embodiment of the present disclosure.

[0010] Figure 2 This is a usage scenario diagram illustrating a screen encryption system according to an embodiment of the present disclosure.

[0011] Figure 3 This is a schematic diagram illustrating multiple grayscale levels of a screen encryption system according to an embodiment of the present disclosure.

[0012] Figure 4 This is a usage scenario diagram illustrating a screen encryption system according to an embodiment of the present disclosure.

[0013] Figure 5 This is a schematic diagram illustrating multiple grayscale levels of a screen encryption system according to an embodiment of the present disclosure.

[0014] Figure 6 This is a schematic diagram illustrating multiple grayscale levels of a screen encryption system according to an embodiment of the present disclosure.

[0015] Figure 7 This is a flowchart illustrating a screen encryption method according to an embodiment of the present disclosure.

[0016] Figure 8 This is a flowchart illustrating a screen encryption method according to an embodiment of the present disclosure.

[0017] In accordance with customary practice, the various features and components in the figures are not drawn to scale, but are drawn in a manner that best represents the specific features and components relevant to this disclosure. Furthermore, similar components / parts are referred to by the same or similar element symbols across different figures.

[0018] Explanation of reference numerals in the attached figures:

[0019] 100: Image Encryption System

[0020] 110: Host

[0021] 111: Memory

[0022] 113: Processor

[0023] 900: Monitor

[0024] 200: Screen

[0025] 210: Region

[0026] 211: Text string

[0027] GH: Encrypted high grayscale

[0028] IG: Displaying grayscale

[0029] GL: Encrypted low grayscale

[0030] T: Time interval

[0031] 200A: Screen

[0032] 210A: Area 1

[0033] 211A: First string

[0034] 220A: Second Zone

[0035] 221A: Second string

[0036] GH1: First Encrypted High Grayscale

[0037] GL1: First Encryption Low Grayscale

[0038] GH2: Second Encryption High Grayscale

[0039] GL2: Second Encryption Low Grayscale

[0040] T1: First time interval

[0041] T2: Second time interval

[0042] TC1: First shutter release time

[0043] TC2: Second shutter stop time

[0044] TC3: Third shutter speed for light reduction

[0045] TC4: Fourth shutter speed for light reduction

[0046] 700, 800: Image encryption methods

[0047] 710~730: Steps

[0048] 810~850: Steps Detailed Implementation

[0049] To make the description of this disclosure more detailed and complete, illustrative descriptions of implementation methods and specific embodiments of this disclosure are provided below; however, this is not the only form of implementing or utilizing the specific embodiments of this disclosure. The implementation methods cover features of multiple specific embodiments and the method steps and their order for constructing and operating these specific embodiments. However, other specific embodiments may also be used to achieve the same or equivalent functions and order of steps.

[0050] Unless otherwise defined in this specification, the scientific and technical terms used herein have the same meaning as understood and commonly used by one of ordinary skill in the art to which this disclosure pertains. Furthermore, unless conflicting with the context, singular nouns used herein include their plural forms, and vice versa.

[0051] Figure 1 This is a block diagram illustrating a screen encryption system according to an embodiment of the present disclosure. As shown, the screen encryption system 100 includes a memory 111 and a processor 113. The memory 111 is coupled to the processor 113 in a connection relationship. In some embodiments, the screen encryption system 100 may include a host 110 and a display 900. The host 110 includes the memory 111 and the processor 113. The display 900 can be used to display images (e.g., as described below). Figure 2 The images shown are 200, but this disclosure is not limited thereto.

[0052] To achieve a text string that is invisible to the human eye but can be captured by a camera, this disclosure provides, for example... Figure 1 The detailed operation instructions for the screen encryption system 100 shown are as follows.

[0053] In one embodiment, memory 111 is used to store a plurality of instructions. Processor 113 is used to perform the following steps according to the plurality of instructions in memory 111: adding a text string to a region of the screen, wherein the text string includes a high grayscale text string and a low grayscale text string; obtaining the average value of the encrypted high grayscale of the high grayscale text string and the encrypted low grayscale of the low grayscale text string within a time interval; and outputting the screen and the text string when the average value is equal to the display grayscale of the screen.

[0054] To make the above operations of the screen encryption system 100 easier to understand, please refer to the following: Figure 2 and Figure 3 , Figure 2 This is a usage scenario diagram illustrating a screen encryption system according to an embodiment of the present disclosure. Figure 3 This is a schematic diagram illustrating multiple grayscale levels of a screen encryption system according to an embodiment of the present disclosure.

[0055] Please refer to the following: Figures 1 to 3In one embodiment, the processor 113 is configured to add a text string 211 to a region 210 in the screen 200 according to a plurality of instructions from the memory 111, and the text string 211 includes a high-grayscale text string and a low-grayscale text string. For example, the region 210 can be any region in the screen 200, the content of the text string 211 can be XXXConfidential or any other text symbol content, the text string 211 can include a high-grayscale text string and a low-grayscale text string with the same text content, and the high-grayscale text string and the low-grayscale text string can be displayed at the same frequency (e.g., 120Hz), but this disclosure is not limited thereto.

[0056] Then, within the time interval (e.g.) Figure 3 Within the time interval T, processor 113 obtains the average of the encrypted high grayscale GH of the high grayscale text string and the encrypted low grayscale GL of the low grayscale text string. For example, within the time interval T, the encrypted high grayscale GH of the high grayscale text string can be 137, and the encrypted low grayscale GL of the low grayscale text string can be 117, so the average can be (137+117)÷2=127. Furthermore, text string 211 can be displayed at a frequency of 60Hz, and the time interval T can be the reciprocal of the frequency f displayed by text string 211 (i.e.,...). Therefore, the time interval T is 1 / 60, and the display time of the encrypted high grayscale GH and the display time of the encrypted low grayscale GL each account for half of the time interval T, which is 1 / 120, but this disclosure is not limited to this.

[0057] Subsequently, when the average value equals the display grayscale IG of screen 200, processor 113 outputs screen 200 and text string 211. For example, the display grayscale IG of screen 200 can be 127, so when the average value of the encrypted high grayscale GH of the high grayscale text string and the encrypted low grayscale GL of the low grayscale text string is 127, processor 113 can output screen 200 and text string 211, but this disclosure is not limited thereto.

[0058] In one embodiment, the text string 211 is displayed on the screen 200 at a frequency. For example, the text string may be displayed on the screen 200 at 60Hz, or at 120Hz, but this disclosure is not limited thereto.

[0059] Furthermore, the image seen by the human eye is the result of a longer integration time (i.e., for the human eye, the time to acquire the image is much longer than the time interval T), while the image seen by the camera is the result of a shorter integration time (i.e., for the camera, the time to capture or acquire the image is less than or equal to the time interval T). Therefore, for the human eye, in the example above, the encrypted high grayscale GH of the high grayscale text string can be 137, and the encrypted low grayscale GL of the low grayscale text string can be 117, so the average value can be 127. And when the display grayscale IG of the image 200 can be 127, for the human eye, since the average value of the encrypted high grayscale GH of the high grayscale text string and the encrypted low grayscale GL of the low grayscale text string is the same as the display grayscale IG, the human eye cannot recognize or acquire the text string 211.

[0060] In contrast, for a camera, if the camera's shutter speed is... When a text string is displayed at 60Hz on screen 200 (at this time, the display time of the high grayscale text string is 1 / 120, and the display time of the low grayscale text string is also 1 / 120), the camera can capture either the high grayscale text string or the low grayscale text string. Of course, if the camera's shutter speed is less than... At the same time, it is also possible to obtain high grayscale text strings or low grayscale text strings.

[0061] However, if the camera's shutter speed is 1 / 60, and the sum of the display times of the high-grayscale text string and the low-grayscale text string can be a time interval T, and the time interval T can be 1 / 60, then in the time interval T, the display grayscale IG of image 200 can be 127, the encrypted high grayscale GH of the high-grayscale text string can be 137, and the encrypted low grayscale GL of the low-grayscale text string can be 117. For the camera, since the average value of the encrypted high grayscale GH of the high-grayscale text string and the encrypted low grayscale GL of the low-grayscale text string is the same as the display grayscale IG, the camera cannot recognize or acquire the text string 211.

[0062] Please see Figure 1 The processor 113 is further configured to perform the following steps according to a plurality of instructions from the memory 111: adding a first text string to a first area of ​​the screen, wherein the first text string includes a first high grayscale text string and a first low grayscale text string; adding a second text string to a second area of ​​the screen, wherein the second text string includes a second high grayscale text string and a second low grayscale text string; obtaining a first average value of a first encrypted high grayscale of the first high grayscale text string and a first encrypted low grayscale of the first low grayscale text string during a first time interval; obtaining a second average value of a second encrypted high grayscale of the second high grayscale text string and a second encrypted low grayscale of the second low grayscale text string during a second time interval; and outputting the screen, the first text string, and the second text string when the first average value and the second average value are equal to the display grayscale of the screen.

[0063] To make the above operations of the screen encryption system 100 easier to understand, please refer to the following: Figure 4 and Figure 5 , Figure 4 This is a usage scenario diagram illustrating a screen encryption system according to an embodiment of the present disclosure. Figure 5 This is a schematic diagram illustrating multiple grayscale levels of a screen encryption system according to an embodiment of the present disclosure.

[0064] Please refer to the following: Figure 1 , Figure 4 and Figure 5 In one embodiment, the processor 113 is further configured to perform the following steps according to a plurality of instructions from the memory 111: adding a first text string 211A to a first region 210A in the screen 200A, wherein the first text string 211A includes a first high grayscale text string and a first low grayscale text string; adding a second text string 221A to a second region 220A in the screen 200A, wherein the second text string 221A includes a second high grayscale text string and a second low grayscale text string. For example, the first region 210A can be any region in the screen 200, and the second region 220A can be any region in the screen 200 other than the first region 210A. The content of the first text string 211A can be XXX Confidential or any other text symbol content. The first text string 211A can contain a first high grayscale text string and a first low grayscale text string with the same text content. Similarly, the content of the first text string 221A can be XXX Confidential or any other text symbol content, and the second text string 221A can contain a second high grayscale text string and a second low grayscale text string with the same text content, but this disclosure is not limited thereto. In one embodiment, the content of the first text string 211A can be XXX Confidential or any other text symbol content. The first text string 211A can contain a first high grayscale text string and a first low grayscale text string with the same text content. In contrast, the content of the first text string 221A can be OOOO Confidential or any other text symbol content different from the first text string 211A. The second text string 221A can contain a second high grayscale text string and a second low grayscale text string with the same text content.

[0065] In one embodiment, during the first time interval T1, the processor 113 obtains the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string. For example, during the first time interval T1, the first encrypted high grayscale GH1 of the first high grayscale text string can be 137, and the first encrypted low grayscale GL1 of the first low grayscale text string can be 117. Therefore, the first average value can be (137+117)÷2=127. Furthermore, the first text string 211A can be displayed at a frequency of 60Hz, and the first time interval T1 can be the reciprocal of the frequency f1 at which the first text string 211A is displayed (i.e., f1). Therefore, the first time interval T1 is 1 / 60, and the display time of the first encrypted high grayscale GH1 and the display time of the first encrypted low grayscale GL1 each account for half of the first time interval T1, which is 1 / 120, but this disclosure is not limited to this.

[0066] In one embodiment, during the second time interval T2, the processor 113 obtains the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string. For example, during the second time interval T2, the second encrypted high grayscale GH2 of the second high grayscale text string can be 147, and the second encrypted low grayscale GL2 of the second low grayscale text string can be 117. Therefore, the second average value can be (147 + 117 × 2) ÷ 3 = 127. Furthermore, the second text string 221A can be displayed at a frequency of 40Hz, and the second time interval T2 can be the reciprocal of the frequency f2 at which the second text string 221A is displayed (i.e., f2). Therefore, the second time interval T2 is 1 / 40, and the display time of the second encrypted high grayscale GH2 accounts for one-third of the second time interval T2, which is 1 / 120. The display time of the second encrypted low grayscale GL2 accounts for two-thirds of the second time interval T2, which is 1 / 60. However, this disclosure is not limited to this.

[0067] In one embodiment, when the first average value and the second average value are equal to the display grayscale of the screen, the processor 113 outputs screen 200A, the first text string 211A, and the second text string 221A. For example, the display grayscale IG of screen 200A can be 127. When the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string is 127, and the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string is also 127, the processor 113 can output screen 200A, the first text string 211A, and the second text string 221A, but this disclosure is not limited thereto.

[0068] In one embodiment, the first text string 211A is displayed on the screen 200A at a first frequency f1. For example, the first frequency f1 can be 60Hz, and the first text string 211A can be displayed on the screen 200A at 60Hz, but this disclosure is not limited thereto.

[0069] In one embodiment, the second text string 221A is displayed on the screen 200A at a second frequency f2. For example, the second frequency f2 can be 40Hz, and the second text string 221A can be displayed on the screen 200A at 40Hz, but this disclosure is not limited thereto.

[0070] Furthermore, the image seen by the human eye is the result of a longer integration time (i.e., for the human eye, the time to acquire the image is much longer than the first time interval T1 or the second time interval T2), while the image seen by the camera is the result of a shorter integration time (i.e., for the camera, the time to capture or acquire the image is less than or equal to the first time interval T1 or the second time interval T2).

[0071] From the perspective of the human eye, in the example above, the first encrypted high grayscale GH1 of the first high grayscale text string can be 137, the first encrypted low grayscale GL1 of the first low grayscale text string can be 117, and the first average value can be 127. The second encrypted high grayscale GH2 of the second high grayscale text string can be 147, the second encrypted low grayscale GL2 of the second low grayscale text string can be 117, and the second average value can be 127. When the display grayscale IG of screen 200A can be 127, for the human eye, since the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string is the same as the display grayscale IG, the human eye cannot recognize or obtain the first text string 211A. Similarly, since the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string is the same as the display grayscale IG, the human eye also cannot recognize or obtain the first text string 221A.

[0072] Figure 6 This is a schematic diagram illustrating multiple grayscale levels of a screen encryption system according to an embodiment of this disclosure. Please refer to... Figure 6 The camera's shutter speed can be a first shutter speed TC1, a second shutter speed TC2, a third shutter speed TC3, or a fourth shutter speed TC4. For example, the first shutter speed TC1 can be 1 / 120, the second shutter speed TC2 can be 1 / 60, the third shutter speed TC3 can be 1 / 40, and the fourth shutter speed TC4 can be 1 / 30, but this disclosure is not limited to these.

[0073] In some embodiments, the first encrypted high grayscale GH1 of the first high grayscale text string can be 137, the first encrypted low grayscale GL1 of the first low grayscale text string can be 117, the second encrypted high grayscale GH2 of the second high grayscale text string can be 147, the second encrypted low grayscale GL2 of the second low grayscale text string can be 117, and the display grayscale IG of the image 200A can be 127. In this case, the first text string 211A can be displayed in the image 200A at 60Hz, and the second text string 221A can be displayed in the image 200A at a frequency of 40Hz. For the camera, when the camera's first shutter light-receiving time TC1 is 1 / 120, the camera can acquire the first text string 211A. Similarly, the camera can also acquire the second text string 221A.

[0074] The main reason is that when the camera's first shutter light-receiving time TC1 is 1 / 120, the camera can acquire either the first encrypted high grayscale GH1 of the first high grayscale text string, the first encrypted low grayscale GL1 of the first low grayscale text string, the second encrypted high grayscale GH2 of the second high grayscale text string, or the second encrypted low grayscale GL2 of the second low grayscale text string, but this disclosure is not limited to this.

[0075] When the camera's second shutter speed TC2 is 1 / 60, the camera cannot acquire the first text string 211A, but it can acquire the second text string 221A. The main reason is that when the second shutter speed TC2 is 1 / 60, the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string acquired by the camera will be the same as the displayed grayscale IG. Therefore, the camera cannot recognize or acquire the first text string 211A. However, the camera can acquire the second encrypted high grayscale GH2 of the second high grayscale text string or the second encrypted low grayscale GL2 of the second low grayscale text string.

[0076] When the camera's third shutter speed (TC3) is 1 / 40, the camera can acquire the first text string 211A, but it cannot acquire the second text string 221A. The main reason is that when the third shutter speed (TC3) is 1 / 40, the camera can acquire either the first encrypted high grayscale GH1 of the first high grayscale text string or the first encrypted low grayscale GL1 of the first low grayscale text string. However, the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string will be the same as the displayed grayscale IG, therefore the camera cannot recognize or acquire the second text string 221A.

[0077] When the camera's fourth shutter speed (TC4) is 1 / 30, the camera cannot acquire the first text string 211A, but it can acquire the second text string 221A. The main reason is that when the fourth shutter speed (TC4) is 1 / 30, the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string acquired by the camera is the same as the displayed grayscale IG. Therefore, the camera cannot recognize or acquire the first text string 211A. However, the camera can acquire the second encrypted high grayscale GH2 of the second high grayscale text string or the second encrypted low grayscale GL2 of the second low grayscale text string.

[0078] Figure 7 This is a flowchart illustrating a screen encryption method according to an embodiment of the present disclosure. As shown in the figure, Figure 7 The image encryption method 700 includes the following steps:

[0079] Step 710: Add a text string to the area in the image, and the text string contains both high grayscale text strings and low grayscale text strings.

[0080] Step 720: Within the time interval, obtain the average value of the encrypted high grayscale of the high grayscale text string and the encrypted low grayscale of the low grayscale text string.

[0081] Step 730: When the average value equals the display grayscale of the image, output the image and text string.

[0082] In order to make Figure 7 The image encryption method 700 is easy to understand; please refer to it as well. Figure 1 , Figure 2 , Figure 3 and Figure 7 In one embodiment, referring to step 710, the processor 113 adds a text string 211 to region 210 in the screen 200, and the text string 211 includes a high-grayscale text string and a low-grayscale text string. For example, region 210 can be any region in the screen 200, the content of text string 211 can be XXX Confidential or any other text symbol content, text string 211 can contain a high-grayscale text string and a low-grayscale text string with the same text content, and the high-grayscale text string and the low-grayscale text string can be displayed at the same frequency (e.g., 120Hz), but this disclosure is not limited thereto.

[0083] In one embodiment, please refer to step 720, within a time interval (e.g. Figure 3Within a time interval T, the processor 113 obtains the average of the encrypted high grayscale GH of the high grayscale text string and the encrypted low grayscale GL of the low grayscale text string. For example, within the time interval T, the encrypted high grayscale GH of the high grayscale text string can be 137, and the encrypted low grayscale GL of the low grayscale text string can be 117. Therefore, the average value can be (137 + 117) ÷ 2 = 127. Furthermore, the text string 211 can be displayed at a frequency of 60Hz, and the time interval T can be the reciprocal of the frequency f of the text string 211 (i.e., f). Therefore, the time interval T is 1 / 60, and the display time of the encrypted high grayscale GH and the display time of the encrypted low grayscale GL each account for half of the time interval T, which is 1 / 120, but this disclosure is not limited to this.

[0084] In one embodiment, referring to step 730, when the average value is equal to the display grayscale IG of screen 200, screen 200 and text string 211 are output by processor 113. For example, the display grayscale IG of screen 200 can be 127. Therefore, when the average value of the encrypted high grayscale GH of the high grayscale text string and the encrypted low grayscale GL of the low grayscale text string is 127, processor 113 can output screen 200 and text string 211, but this disclosure is not limited thereto.

[0085] In one embodiment, referring to step 710, the text string 211 is displayed on the screen 200 at a frequency. For example, the text string can be displayed on the screen 200 at 60Hz, or at a frequency of 120Hz, but this disclosure is not limited thereto.

[0086] Figure 8 This is a flowchart illustrating a screen encryption method according to an embodiment of the present disclosure. As shown in the figure, Figure 8 The image encryption method 800 includes the following steps:

[0087] Step 810: Add a first text string to the first area of ​​the image, and the first text string includes a first high grayscale text string and a first low grayscale text string.

[0088] Step 820: Add a second text string to the second area of ​​the image, and the second text string contains a second high grayscale text string and a second low grayscale text string;

[0089] Step 830: In the first time interval, obtain the first average value of the first encrypted high gray level of the first high gray level text string and the first encrypted low gray level of the first low gray level text string;

[0090] Step 840: In the second time interval, obtain the second average value of the second encrypted high grayscale of the second high grayscale text string and the second encrypted low grayscale of the second low grayscale text string;

[0091] Step 850: When the first average value and the second average value are equal to the display grayscale of the screen, output the screen, the first text string, and the second text string.

[0092] In order to make Figure 8 The image encryption method 700 is easy to understand; please refer to it as well. Figure 1 , Figure 4 , Figure 5 , Figure 6 and Figure 8 In one embodiment, please refer to step 810, where the processor 113 adds a first text string 211A to the first area 210A in the screen 200A, and the first text string 21A includes a first high grayscale text string and a first low grayscale text string.

[0093] In one embodiment, referring to step 820, the processor 113 adds a second text string 221A to the second region 220A in the screen 200A, and the second text string 221A includes a second high-grayscale text string and a second low-grayscale text string. For example, the first region 210A can be any region in the screen 200, and the second region 220A can be any region in the screen 200 other than the first region 210A. The content of the first text string 211A can be "XXX Confidential" or any other text symbol content. The first text string 211A can include a first high-grayscale text string and a first low-grayscale text string with the same text content. Similarly, the content of the first text string 221A can be "XXX Confidential" or any other text symbol content, and the second text string 221A can include a second high-grayscale text string and a second low-grayscale text string with the same text content, but this disclosure is not limited thereto. In one embodiment, the content of the first text string 211A can be XXX Confidential or any other text symbol content. The first text string 211A can contain a first high grayscale text string and a first low grayscale text string with the same text content. In contrast, the content of the first text string 221A can be OOOO Confidential or any other text symbol content different from the first text string 211A. The second text string 221A can contain a second high grayscale text string and a second low grayscale text string with the same text content.

[0094] In one embodiment, referring to step 830, during the first time interval T1, the processor 113 obtains the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string. For example, during the first time interval T1, the first encrypted high grayscale GH1 of the first high grayscale text string can be 137, and the first encrypted low grayscale GL1 of the first low grayscale text string can be 117. Therefore, the first average value can be (137+117)÷2=127. In addition, the first text string 211A can be displayed at a frequency of 60Hz, and the first time interval T1 can be the reciprocal of the frequency f1 at which the first text string 211A is displayed (i.e., f1). Therefore, the first time interval T1 is 1 / 60, and the display time of the first encrypted high grayscale GH1 and the display time of the first encrypted low grayscale GL1 each account for half of the first time interval T1, which is 1 / 120, but this disclosure is not limited to this.

[0095] In one embodiment, referring to step 840, during the second time interval T2, the processor 113 obtains the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string. For example, during the second time interval T2, the second encrypted high grayscale GH2 of the second high grayscale text string can be 147, and the second encrypted low grayscale GL2 of the second low grayscale text string can be 117. Therefore, the second average value can be (147 + 117 × 2) ÷ 3 = 127. Furthermore, the second text string 221A can be displayed at a frequency of 40Hz, and the second time interval T2 can be the reciprocal of the frequency f2 displayed by the second text string 221A (i.e., f2). Therefore, the second time interval T2 is 1 / 40, and the display time of the second encrypted high grayscale GH2 accounts for one-third of the second time interval T2, which is 1 / 120. The display time of the second encrypted low grayscale GL2 accounts for two-thirds of the second time interval T2, which is 1 / 60. However, this disclosure is not limited to this.

[0096] In one embodiment, referring to step 850, when the first average value and the second average value are equal to the display grayscale of the screen, the processor 113 outputs screen 200A, the first text string 211A, and the second text string 221A. For example, the display grayscale IG of screen 200A can be 127. When the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string is 127, and the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string is also 127, the processor 113 can output screen 200A, the first text string 211A, and the second text string 221A, but this disclosure is not limited thereto.

[0097] In one embodiment, referring to step 810, the processor 113 displays the first text string 211A on the screen 200A at a first frequency f1. For example, the first frequency f1 can be 60Hz, and the first text string 211A can be displayed on the screen 200A at 60Hz, but this disclosure is not limited thereto.

[0098] In one embodiment, referring to step 810, the processor 113 displays the second text string 221A on the screen 200A at a second frequency f2. For example, the second frequency f2 can be 40Hz, and the second text string 221A can be displayed on the screen 200A at 40Hz, but this disclosure is not limited thereto.

[0099] Furthermore, the image seen by the human eye is the result of a longer integration time (i.e., for the human eye, the time to acquire the image is much longer than the first time interval T1 or the second time interval T2), while the image seen by the camera is the result of a shorter integration time (i.e., for the camera, the time to capture or acquire the image is less than or equal to the first time interval T1 or the second time interval T2).

[0100] From the perspective of the human eye, in the example above, the first encrypted high grayscale GH1 of the first high grayscale text string can be 137, the first encrypted low grayscale GL1 of the first low grayscale text string can be 117, and the first average value can be 127. The second encrypted high grayscale GH2 of the second high grayscale text string can be 147, the second encrypted low grayscale GL2 of the second low grayscale text string can be 117, and the second average value can be 127. When the display grayscale IG of screen 200A can be 127, for the human eye, since the first average value of the first encrypted high grayscale GH1 of the first high grayscale text string and the first encrypted low grayscale GL1 of the first low grayscale text string is the same as the display grayscale IG, the human eye cannot recognize or obtain the first text string 211A. Similarly, since the second average value of the second encrypted high grayscale GH2 of the second high grayscale text string and the second encrypted low grayscale GL2 of the second low grayscale text string is the same as the display grayscale IG, the human eye also cannot recognize or obtain the first text string 221A.

[0101] As can be seen from the above embodiments of this disclosure, applying this disclosure has the following advantages. The image encryption system and image encryption method shown in the embodiments of this disclosure can achieve the effect that the text string is invisible to the human eye, but can be captured by the camera when shooting, by adjusting the display frequency of high and low gray levels in the text string.

[0102] Although specific embodiments of this disclosure have been disclosed in the foregoing embodiments, they are not intended to limit this disclosure. Those skilled in the art to which this disclosure pertains can make various changes and modifications without departing from the principles and concepts of this disclosure. Therefore, the scope of protection of this disclosure shall be determined by the appended claims.

Claims

1. A picture encryption system, comprising: a memory for storing a plurality of instructions; and a processor for executing the following steps according to the instructions of the memory: adding a text string to a region in a picture, wherein the text string comprises a high gray scale text string and a low gray scale text string; obtaining an average value of an encrypted high gray scale of the high gray scale text string and an encrypted low gray scale of the low gray scale text string in a time interval; outputting the picture and the text string when the average value is equal to a display gray scale of the picture; displaying the high gray scale text string in a first region of the picture in a first time interval; displaying the low gray scale text string in the first region of the picture in a second time interval; displaying the high gray scale text string in a second region of the picture in the first time interval; and displaying the low gray scale text string in the second region of the picture in the second time interval and a third time interval; wherein the second time interval is subsequent to the first time interval, the third time interval is subsequent to the second time interval, a time length of the second time interval plus a time length of the third time interval is greater than a time length of the first time interval, and the region comprises the first region and the second region.

2. The picture encryption system of claim 1, wherein the text string is displayed in the picture at a frequency.

3. The picture encryption system of claim 1, wherein the processor is further for executing the following steps according to the instructions of the memory: adding a first text string to the first region of the picture, wherein the first text string comprises a first high gray scale text string and a first low gray scale text string; adding a second text string to the second region of the picture, wherein the second text string comprises a second high gray scale text string and a second low gray scale text string; obtaining a first average value of a first encrypted high gray scale of the first high gray scale text string and a first encrypted low gray scale of the first low gray scale text string in the first time interval; obtaining a second average value of a second encrypted high gray scale of the second high gray scale text string and a second encrypted low gray scale of the second low gray scale text string in the second time interval; and outputting the picture, the first text string and the second text string when the first average value and the second average value are equal to the display gray scale of the picture.

4. The picture encryption system of claim 3, wherein the first text string is displayed in the picture at a first frequency.

5. The picture encryption system of claim 4, wherein the second text string is displayed in the picture at a second frequency.

6. A picture encryption method, comprising: adding a text string to a region in a picture, wherein the text string comprises a high gray scale text string and a low gray scale text string; obtaining an average value of an encrypted high gray scale of the high gray scale text string and an encrypted low gray scale of the low gray scale text string in a time interval; outputting the picture and the text string when the average value is equal to a display gray scale of the picture; displaying the high gray scale text string in a first region of the picture in a first time interval; displaying the low gray scale text string in the first region of the picture in a second time interval; displaying the high gray scale text string in a second region of the picture in the first time interval; and displaying the low gray scale text string in the second region of the picture in the second time interval and a third time interval; wherein the second time interval is subsequent to the first time interval, the third time interval is subsequent to the second time interval, a time length of the second time interval plus a time length of the third time interval is greater than a time length of the first time interval, and the region comprises the first region and the second region. displaying the low gray scale text string in the first region in the picture in a second time interval; displaying the high gray scale text string in a second region in the picture in the first time interval; and displaying the low gray scale text string in the second region in the picture in the second time interval and a third time interval; wherein the second time interval is subsequent to the first time interval, the third time interval is subsequent to the second time interval, a time length of the second time interval plus a time length of the third time interval is greater than a time length of the first time interval, and the region includes the first region and the second region.

7. The picture encryption method of claim 6, wherein the high gray scale text string and the low gray scale text string are displayed in the picture at a frequency.

8. The picture encryption method of claim 6, wherein the region in the picture plus the text string, wherein the text string includes the high gray scale text string and the low gray scale text string, comprises: applying a first text string to the first region in the picture, wherein the first text string includes a first high gray scale text string and a first low gray scale text string; and applying a second text string to the second region in the picture, wherein the second text string includes a second high gray scale text string and a second low gray scale text string.

9. The picture encryption method of claim 8, wherein the first high gray scale text string and the first low gray scale text string are displayed in the picture at a first frequency, wherein the second high gray scale text string and the second low gray scale text string are displayed in the picture at a second frequency.

10. The picture encryption method of claim 8, wherein the step of obtaining the average of the encrypted high gray scale of the high gray scale text string and the encrypted low gray scale of the low gray scale text string in the time interval comprises: obtaining a first average of a first encrypted high gray scale of the first high gray scale text string and a first encrypted low gray scale of the first low gray scale text string in the first time interval; and obtaining a second average of a second encrypted high gray scale of the second high gray scale text string and a second encrypted low gray scale of the second low gray scale text string in the second time interval; wherein the step of outputting the picture and the text string when the average is equal to the display gray scale of the picture comprises: outputting the picture, the first text string and the second text string when the first average and the second average are equal to the display gray scale of the picture.

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