An image sensor for a digital camera, a digital camera, and a method for manufacturing an optical identity marker

Abstract

An image sensor (14), a digital camera (10), and a method for manufacturing an optical identity marker arranged on the image sensor (14). The image sensor (14) comprises a predefined manipulated pattern (21) placed on an optical receiving layer (141) of the image sensor (14). The predefined manipulated pattern (21) is configured to adjust the number of incoming rays of light (13) from reaching a portion of the photoelectric conversion layer (142); A method for manufacturing an optical identity marker comprises an image sensor having a base layer (143), an optical receiving layer (141) and a photoelectric conversion layer (142), manipulating the optical receiving layer (141) by a marking device; and producing a predefined manipulated pattern (21) to the optical receiving layer (141).

Description

[0001] AN IMAGE SENSOR FOR A DIGITAL CAMERA, A DIGITAL CAMERA, AND A

[0002] METHOD FOR MANUFACTURING AN OPTICAL IDENTITY MARKER

[0003] BACKGROUND

[0004] Digital imaging is prone to editing, filtering or even forgery. The recipient may not entirely trust the integrity and veracity of digital images or videos.

[0005] Backgrounds may be changed for a video conference; participant’s faces may be enhanced or even changed by the artificial intelligence technology nowadays. In one example, deepfakes are synthetic videos or images, where existing image or video is replaced convincingly with someone else's likeness, or entirely synthetic human-like images and videos by artificial intelligence and deep learning algorithms. As the artificial intelligence technology advances, it becomes increasingly difficult to tell apart real content and fake content. Whatever the digital camera has captured, may be later altered.

[0006] Participants of video conferences are currently trusted by very simple methods. As one example, during the opening procedures of video conferences at the European Patent Office, the participants are recognized by showing their identity cards or passports to the camera. It is obvious that such documents may not be verified, as forged documents would have a similar appearance.

[0007] The real-world objects in photographs are difficult to verify. Various technologies have been introduced to mitigate the problem. The object may have an embedded RFID tag, NFC tag or a QR code that may be certified as part of its digital image. The image sensor may add metadata of the object into the image data. The digital image may be watermarked, or digital signatures may be embedded into the image data and verify the origin and integrity of digital image by blockchain technology to ensure its authenticity. SUMMARY

[0008] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0009] An image sensor for a digital camera, a digital camera, and a method for manufacturing an optical identity marker are disclosed hereinafter. The image sensor is one of the important components of any digital camera. The image sensor for a digital camera comprises a base layer, an optical receiving layer, and a photoelectric conversion layer. One example of the base layer is a silicone base layer. The optical receiving layer allowing incoming rays of light to pass through may comprise a microlens and a color filter array. The microlens focuses incoming rays of light onto the photoelectric conversion layer, while the color filter array is configured to capture color information. One example of the color filter array is a Bayer filter. The photoelectric conversion layer is configured to capture rays of light from the optical receiving layer and to generate digital signals. The photoelectric conversion layer may comprise a photodiode array and an on-chip circuitry. Through the photodiode array, the information carried by light is transformed into electrical signals. One example of the on-chip circuitry is an Analog-to-Digital Converter (ADC). The three-layer structure of the image sensor, along with auxiliary structures, for example, a bus and an image processor in a digital camera, enables to capture moments in real world.

[0010] The image sensor for a digital camera has an additional optical identity marker on the optical receiving layer, which provides a predefined manipulated pattern to image or video stream captured with the image sensor of the camera. Exemplary image sensor types for the digital camera are a Charge-Coupled Device (CCD) and a Complementary Metal-Oxide-Semiconductor (CMOS). The camera is in one example a complete module suitable for smartphones, laptops, or tablet computers. The camera has a lens configured to focus incoming rays of light onto the image sensor.

[0011] The optical receiving layer of the image sensor comprises a predefined manipulated pattern as an optical identity marker. The optical receiving layer allows some of the incoming rays of light to pass through.

[0012] In one embodiment, the predefined manipulated pattern on the optical receiving layer is configured to attenuate incoming rays of light from reaching a portion of the photoelectric conversion layer. Part of the incoming rays of light can even be totally blocked by the predefined manipulated pattern.

[0013] In one embodiment, the predefined manipulated pattern on the optical receiving layer is configured to intensify incoming rays of light from reaching a portion of the photoelectric conversion layer. One example of intensifying incoming rays of light is focusing multiple incoming rays of light reaching the photoelectric conversion layer by convex lens. One example of intensifying incoming rays of light is damaging or removing optical receiving layer from image sensor, allowing more incoming rays of light passing through the optical receiving layer and reaching the photoelectric conversion layer.

[0014] In one example the predefined manipulated pattern allows portion of incoming rays of light, that were previously blocked either at the optical receiving layer or at the photoelectric conversion layer before manipulation. In some examples the optical receiving layer or the photoelectric conversion layer comprise attenuating or blocking elements that may be removed by the predefined manipulated pattern.

[0015] Thus, the flux of rays of light reaching the photoelectric conversion layer is adjusted where the predefined manipulated pattern exists. The photoelectric conversion layer on the image sensor generates corresponding electrical signals based on the different light intensity and color that hits it.

[0016] Through the ADC conversion, the continuous electrical signals, which are the analog signals, are transformed into digital signals. These digital signals correspond to the light intensity and color of different parts of the image. Subsequently, the image processor uses the digital signals to construct a digital image.

[0017] In one example, the predefined manipulated pattern attenuates incoming rays of light. In one example, the predefined manipulated pattern intensifies incoming rays of light. The light intensity changes before rays of light reach the photoelectric conversion layer. After the photoelectric conversion, the digital signals representing the location of the predefined manipulated pattern can significantly differ from those adjacent to the pattern's location. Through the above-mentioned procedures, a dark or a bright predefined manipulated pattern as an optical identify marker is visible on the digital image.

[0018] In one embodiment, in one predefined manipulated pattern, some part of the predefined manipulated pattern on the optical receiving layer is configured to attenuate incoming rays of light, and other part of the predefined manipulated pattern is configured to intensify incoming rays of light.

[0019] In one embodiment, the marking of the predefined manipulated pattern attenuating incoming rays of light is produced by a first marking device. The marking of the predefined manipulated pattern intensifying incoming rays of light is produced by a second marking device. The predefined manipulated pattern produced by the different marking devices is difficult to replicate, thereby increasing the security of predefined manipulated pattern.

[0020] Human eye may detect similar entoptic phenomenon during an ophthalmologic examination. This phenomenon, called Purkinje tree is an image of the retinal blood vessels in one's own eye. When a beam of small bright light shines through the pupil from the periphery of a subject's vision, the position of light is not normal to human, so the abnormal light position casts shadows of the blood vessels onto unadapted portions of the retina. Normally, human brain has been adapted to compensate the blood vessels from the vision. In this rare situation the shadows become visible. Therefore, human eye is reactive to shadows in the vicinity of the retinal cells.

[0021] The predefined manipulated pattern may directly provide the optical identity markers. The predefined manipulated pattern may comprise 1 D or 2D barcodes that have an identification information. The predefined manipulated pattern may comprise a unique pattern as a profile that is configured to verify the user’s identification.

[0022] The predefined manipulated pattern may indirectly provide an optical tag. The predefined manipulated pattern may provide multiple optical effects to the image sensor. The predefined manipulated may comprise at least partially a polarizing filter that filters, for example, reflection from a surface. The predefined manipulated may comprise a grating that produces a diffraction effect to the image sensor. The predefined manipulated may apply techniques such as holography, optically variable device (OVD) or diffractive optically variable image device (DOVID).

[0023] Detecting the optical tag is based on the mutual effect of the predefined manipulated pattern and the external optical identity pattern. Examples of the optical identity pattern are security holograms that may be attached or embedded to labels, quality products or to security items such as passports, credit cards or banknotes. Holograms are very difficult to forge because they are replicated from a master hologram which requires expensive, specialized and technologically advanced equipment.

[0024] The optical effect of the optical identity pattern interacts with the predefined manipulated pattern placed on the image sensor to provide another image. The optical identity pattern reflects a first predefined light pattern that is further filtered or altered by the predefined manipulated pattern to produce a second predefined light pattern.

[0025] The predefined manipulated pattern as an optical identity marker is manufactured by a marking device. The marking device comprises the first marking device and the second marking device. The method comprises steps of manipulating the optical receiving layer by the marking device and producing a predefined manipulated pattern. The example of the marking device is a physical marking device, for example, a laser engraver, or a device that engraves by hard materials, like a diamond or a tungsten carbide router bit; a chemical marking device, using a photoresist or other chemical materials to manufacture the markings through etching. The predefined manipulated pattern may be printed by the printer as well. Multiple colorful inks may be used to print the predefined manipulated pattern. With colorful inks, the optical identify marker may show different colors on the digital images.

[0026] In one embodiment, when an image sensor has already been produced, the optical identity marker has already been manufactured on the optical receiving layer as well. When the user applies the digital camera, the predefined manipulated pattern may not be modified, removed, or erased any more. Each image sensor may have its own predefined manipulated pattern. The predefined manipulated pattern is embedded in the digital image captured with the digital camera. The predefined manipulated pattern as the optical identity marker is configured to be used to verify the authenticity of image and the video stream, and to confirm the actual physical camera identity used to provide that image or video stream.

[0027] For example, during the starting moments of a video conference session either party may verify from the image or video feed that the image contains the predefined manipulated pattern as the optical identity marker. The predefined manipulated pattern may be shown on the digital image by applying external light directly to the camera, for example, pointing a smartphone flashlight temporarily onto the laptop camera containing the optical identity marker.

[0028] As the camera itself is verified, the next steps of verifying the content of the video feed become easier. The short distance between the optical receiving layer and the photoelectric conversion layer of the image sensor may cause slight variation in the pixels affected by the pattern. For example, moving the flashlight may be required to cause variation to image to further verify the video stream. The image sensor typically has millions of pixels, therefore it is possible to detect the variation at a small area. Detecting this variation may be used to verify the image sensor and the camera.

[0029] Alternatively, or in addition, the predefined manipulated pattern comprises a three-level encoding. Level 1 comprises screen information. The predefined manipulated pattern may be a unique pattern for each digital camera. The pattern is visible on the screen by applying external light directly to the camera.

[0030] Level 2 comprises markings information. The markings of the predefined manipulated pattern may be unique as well. The marking device produces specific dots that form the markings on the optical receiving layer. Incoming rays of light passing through the optical receiving layer, captured with the photoelectric conversion layer, gain their own unique grayscale patterns. Through the image processor of the digital camera, the pixel values of each dot are configured as fingerprints of the marking. The fingerprints of the marking of the predefined manipulated pattern can be verified by a verification device or software.

[0031] Level 3 comprises size information. The information on the distance between two markings of the predefined manipulated pattern may be unique, expressed in pixel values. In one example, the size information can be verified by the verification device or the software as well.

[0032] The predefined manipulated pattern manufactured on the image sensor allows various security solutions and verification methods that may be used in conjunction with traditional verification and / or authentication methods. As one example, face recognition systems may be applied to further increase the reliability of the authentication. The hardware used in the video conference may be verified to increase validity of other methods. Video conferences may become increasingly reliable, as both parties may verify their true identities with the trusted camera hardware.

[0033] The predefined manipulated pattern as an optical identity marker provides a visual image to each image or video stream. Camera forensics may be used to verify each image as authentic and specify the device that has taken the image or video. An optical tag may be used as a further tool with the camera forensics. The optical tag may change according to various lighting conditions or lighting directions, thus making counterfeiting more difficult.

[0034] Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings. The embodiments described below are not limited to implementations which solve any or all the disadvantages of identification systems or methods, or any image marking solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present description will be better understood from the following detailed description read in light of the accompanying drawings, wherein

[0036] FIG. 1 illustrates schematically one exemplary embodiment of a camera;

[0037] FIG. 2 illustrates schematically a detail view of an image sensor assembly with a predefined manipulated pattern;

[0038] FIG. 3 illustrates schematically one exemplary view of a video stream, or an image captured with the image sensor;

[0039] FIG. 4 illustrates schematically one exemplary view of a video stream, or an image captured with the image sensor;

[0040] FIG. 5 illustrates schematically one exemplary view of the predefined manipulated pattern manufactured by a single-pulse laser;

[0041] FIG. 6 illustrates schematically one exemplary view of the predefined manipulated pattern manufactured by a multiple-pulse laser;

[0042] FIG. 7a illustrates schematically one exemplary view of the predefined manipulated pattern manufactured by a multiple-pulse laser and captured with the photoelectric conversion layer;

[0043] FIG. 7b illustrates schematically one exemplary view of the predefined manipulated pattern manufactured by a single-pulse laser and captured with the photoelectric conversion layer;

[0044] FIG. 7c illustrates schematically one exemplary view of the predefined manipulated pattern manufactured by a mechanical device and captured with the photoelectric conversion layer;

[0045] FIG. 8 illustrates a flowchart of a method for marking information production;

[0046] FIG. 9 illustrates schematically one exemplary view of three-level encoding embedded in a predefined manipulated pattern;

[0047] FIG.1 Oa illustrates schematically one exemplary view of a structure of an image sensor; FIG.10b illustrates schematically one exemplary view of a structure of a photoelectric conversion layer;

[0048] FIG.1 Oc illustrates schematically a side view of one example of a structure of a photoelectric conversion layer;

[0049] FIG.1 Od illustrates schematically a side view of one example of a structure of a photoelectric conversion layer;

[0050] FIG.1 Oe illustrates schematically a side view of one example of a structure of a photoelectric conversion layer; and

[0051] FIG. 11 illustrates a flowchart of a method for manufacturing an optical identity marker.

[0052] Like reference numerals are used to designate like parts in the accompanying drawings.

[0053] DETAILED DESCRIPTION

[0054] The detailed description provided below in connection with the accompanying drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. However, the same or equivalent functions and sequences may be accomplished by different examples.

[0055] Although the present examples are described and illustrated herein as being implemented in identifying a session, a person or a device, these are provided as an example and not a limitation. As those skilled in the art will appreciate, the present examples are suitable for application in a variety of authentication, verification or identification by a variety of devices, systems or methods.

[0056] FIG. 1 illustrates schematically one exemplary embodiment of a camera comprising an image sensor 14, receiving incoming rays of light 13 from a lens 11 . One example of the lens 11 is a movable lens group or a lens module. The image sensor 14 is configured to receive incoming rays of light 13 from the lens 11 . An optical path is defined as a trajectory that a ray of light follows as it propagates through the camera 10.

[0057] The image sensor 14 for a digital camera 10 comprises a base layer 143, an optical receiving layer 141 , and a photoelectric conversion layer 142. FIG’s. 10a to 10e illustrate examples of the structure of the image sensor 14 and the structure of the photoelectric conversion layer 142. From top to bottom, the structure of the image sensor 14 is configured as the optical receiving layer 141 , the photoelectric conversion layer 142, and the base layer 143.

[0058] In one embodiment, the base layer 143 is a silicone base. The optical receiving layer 141 is configured to allow incoming rays of light 13 to pass through. The photoelectric conversion layer 142 is configured to capture rays of light from the optical receiving layer 141 and to generate digital signals. Through the three layers structure of image sensor 14 for a digital camera 10 and other auxiliary structures, the moments in real world are captured with the digital camera.

[0059] In one embodiment, the photoelectric conversion layer 142 comprises a photodiode array 144 and an on-chip circuitry 145. In one embodiment, the photodiode array 144 and the on-chip circuitry 145 are on the same plane within the photoelectric conversion layer 142. In one embodiment, the photodiode array 144 is on the top of the on-chip circuitry 145.

[0060] In one embodiment, the photoelectric conversion layer 142 comprises a photodiode array 144 and an on-chip circuitry 145. A portion of the photodiode array 144 is configured to be embedded in the optical receiving layer 141 . A portion of the on-chip circuitry 145 is configured to be embedded in the base layer 143. In one embodiment, the photodiode array 144 comprises multiple photodiodes.

[0061] In one embodiment, the optical receiving layer 141 of the image sensor 14 comprises a predefined manipulated pattern 21 . When the image sensor 14 is produced, the predefined manipulated pattern 21 as an optical identity marker is manufactured on the optical receiving layer 141 of the image sensor 14.

[0062] The predefined manipulated pattern 21 herein is not limited to a particular location of the optical receiving layer 141 . FIG. 2 illustrates schematically a detail view of an image sensor assembly with a predefined manipulated pattern, on top of the image sensor 14. The predefined manipulated pattern 21 is configured to adjust the number of incoming rays of light 13 from reaching a portion of the photoelectric conversion layer 142.

[0063] In one embodiment, the predefined manipulated pattern 21 is configured to attenuate incoming rays of light 13 from reaching a portion of the photoelectric conversion layer 142, which means that the number of incoming rays of light 13 reaching the photoelectric conversion layer 142 is reduced, making the area dark.

[0064] In one embodiment, the predefined manipulated pattern 21 is configured to attenuate incoming rays of light 13 passing through a silhouette defined by an outline of the predefined manipulated pattern 21 .

[0065] In one embodiment, the predefined manipulated pattern 21 is configured to directly block part of the incoming rays of light 13 from reaching a portion of the photoelectric conversion layer 142. The number of incoming rays of light 13 reaching the photoelectric conversion layer 142 is reduced, making the area dark.

[0066] In one embodiment, the predefined manipulated pattern 21 is configured to intensity incoming rays of light 13 from reaching a portion of the photoelectric conversion layer 142, which means that the number of incoming rays of light 13 reaching the photoelectric conversion layer 142 is increased, making the area bright.

[0067] In one embodiment, the predefined manipulated pattern 21 is configured to intensify incoming rays of light 13 passing through a silhouette defined by an outline of the predefined manipulated pattern 21 .

[0068] In one embodiment, the example of the silhouette defined by an outline of the predefined manipulated pattern 21 is a silhouette of a QR code 23.

[0069] Examples of the image sensor 14 for digital camera 10 may be implemented to devices such as laptop computers, tablet computers, smartphones or dedicated compact cameras or video conference cameras. Each digital camera 10 has one image sensor 14. The device may comprise multiple cameras 10 at one side or different sides of the device, wherein the predefined manipulated pattern 21 may be implemented to one digital camera 10, to multiple digital cameras 10 or all digital cameras 10.

[0070] In one embodiment, the predefined manipulated pattern 21 is configured to be manipulated by a marking device. In one embodiment, the predefined manipulated pattern 21 comprises markings, engraved on the optical receiving layer 141 by an engraving tool. The markings are manufactured on the image sensor 14 at the time of production of the image sensor 14.

[0071] In one embodiment, one example of the engraving tool is a laser engraver. FIG. 5 illustrates schematically one exemplary view of the predefined manipulated pattern manufactured on the image sensor by a single-pulse laser and captured with the photoelectric conversion layer 142. One single-pulse laser dot is configured as a first dot 31 . In one embodiment, each marking of the predefined manipulated pattern 21 comprises one first dot 31 .

[0072] In one embodiment, a laser engraver is configured to produce the first dot 31 using the single-pulse laser. In one embodiment, each first dot 31 has its own unique feature, for example, the depth of engraving, or the width of engraving.

[0073] When the incoming rays of light 13 pass through the optical receiving layer 141 and are captured with the photoelectric conversion layer 142, each first dot 31 will acquire a unique grayscale pattern through camera’s processing algorithms.

[0074] In one embodiment, each first dot 31 is configured as multiple pixels on the image sensor 14. In one embodiment, the laser engraver is configured to provide the first dot 31 with 7 pm diameter. In one embodiment, the size of the pixel of the image sensor is configured under 2 pm. In one embodiment, the diameter of the first dot 31 and the size of the pixel are arranged to other suitable values.

[0075] FIG. 6 illustrates schematically one exemplary view of the predefined manipulated pattern manufactured on the image sensor by a multiple-pulse laser and captured with the photoelectric conversion layer 142. A group of multiple-pulse laser dots are configured as a group of second dots 42. In one embodiment, each marking of the predefined manipulated pattern 21 comprises a group of second dots 42.

[0076] In one embodiment, the laser engraver is configured to produce multiple second dots 42 using the multiple-pulse laser. In one embodiment, each second dot 42 is configured to have its own unique feature, for example, the depth of engraving, or the width of engraving.

[0077] When the incoming rays of light 13 pass through the optical receiving layer 141 and are captured with the photoelectric conversion layer 142, each second dot 42 will acquire a unique grayscale pattern through camera’s processing algorithms.

[0078] In one embodiment, each second dot 42 is configured as one pixel. In one embodiment, the laser engraver is configured to provide a group of 10 x 10 pm second dots 42 formed a square marking 41 . In one embodiment, the second dots 42 within a square marking 41 are configured to be arranged in a grid pattern, managed both vertically and horizontally.

[0079] In one embodiment, the engraving tool is a mechanical device made of hard materials. FIG. 7c illustrates schematically one exemplary view of the predefined manipulated pattern manufactured on the image sensor by a mechanical device and captured with the photoelectric conversion layer 142. In one embodiment, examples of the hard materials are diamond, tungsten carbide or other suitable materials that may be used as a router bit guided by a CNC router. In one embodiment, each marking of the predefined manipulated pattern 21 comprises one single dot 53.

[0080] In one embodiment, a mechanical device is configured to produce a single dot 53 using hard materials for each marking of the predefined manipulated pattern 21 . The single dot 53 is configured as a permanent scratch dot. In one embodiment, each marking of the predefined manipulated pattern 21 comprises one single dot 53. In one embodiment, each marking of the predefined manipulated pattern 21 comprises multiple single dots 53.

[0081] In one embodiment, each single dot 53 has its own unique feature, for example, the depth of engraving, or the width of engraving. When the incoming rays of light 13 pass through the optical receiving layer 141 and are captured with the photoelectric conversion layer 142, each single dot 53 will acquire a unique grayscale pattern through camera’s processing algorithms. In one embodiment, each single dot 53 is configured from multiple pixels.

[0082] In one embodiment, engraving is configured to be used to produce holographic effects, diffraction and / or refraction.

[0083] In one embodiment, the predefined manipulated pattern 21 comprises markings, etched on the optical receiving layer 141 by an etching tool. In one embodiment, examples of the etching tool are glass etching cream, sandblasting equipment, or other suitable tools.

[0084] In one embodiment, etching is configured to be used to produce holographic effects, diffraction and / or refraction. In one embodiment, the etching is provided by an electron beam technology that may provide even smaller linewidths.

[0085] In one embodiment, the predefined manipulated pattern 21 comprises markings, printed on the optical receiving layer 141 by a printing tool. In one example, the printing tool is configured as a printer using inks.

[0086] In one embodiment, the multiple inks are configured to have multiple different colors. The optical receiving layer 141 comprises a colorful predefined manipulated pattern 21 . When the external light passes through the optical receiving layer 141 , the photoelectric conversion layer 142 is configured to capture the colorful light passing through a silhouette defined by an outline of the predefined manipulated pattern 21 .

[0087] In one embodiment, the ink is opaque. In one embodiment, the ink is partially transparent.

[0088] In one embodiment, the ink comprises optical characteristics, such as a refractive index configured to allow incoming rays of light 13 to travel through the ink, and refract, to provide an optical effect to the image sensor 14. The small scale of the ink allows producing holographic effects, diffraction and / or refraction.

[0089] In one embodiment, the marking of the predefined manipulated pattern 21 is configured to attenuate incoming rays of light 13. In one embodiment, the marking of the predefined manipulated pattern 21 is configured to block part of incoming rays of light 13. The digital image or video stream resulting from the attenuating or blocking process will appear darker at the positions corresponding to the to the specific dots on the optical receiving layer 141 .

[0090] In one embodiment, the marking of the predefined manipulated pattern 21 is configured to intensify incoming rays of light 13. In one embodiment, each marking of the predefined manipulated pattern 21 comprises at least one convex lens. The convex lens of the marking is configured to focus multiple incoming rays of light reaching a portion of the photoelectric conversion layer 142.

[0091] In one embodiment, the marking of the predefined manipulated pattern 21 is configured to damage and / or remove the optical receiving layer, allowing more incoming rays of light passing through the optical receiving layer and reaching the photoelectric conversion layer.

[0092] The digital image or video stream resulting from the intensifying process will appear brighter at the positions corresponding to the specific dots on the optical receiving layer 141 .

[0093] In one embodiment, the specific dots are configured to be manipulated on the optical receiving layer 141 by the marking device with gaps. In one embodiment, the specific dots are configured to be manipulated on the optical receiving layer 141 by the marking device without any gaps. The specific points overlap each other.

[0094] In one embodiment, the specific dots are configured to attenuate incoming rays of lights 13. The number of rays of light 13 reaching a portion of the photoelectric conversion layer 142 is reduced. The specific dots are configured to modify the light transmittance of the optical receiving layer 141 . In one embodiment, the specific dots are configured to modify the light transmittance of the optical receiving layer 14 to be greater than 0%, but less than 100%.

[0095] In one embodiment, the specific dots are configured to block incoming rays of lights 13. In one embodiment, the specific dots are configured to modify the light transmittance of the optical receiving layer 14 to be equal to 0%, incoming rays of light 13 are unable to pass through the specific points.

[0096] In one embodiment, incoming rays of light 13 are configured to pass through the optical receiving layer 141 where no specific points are present. The number of rays of light 13 reaching a portion of the photoelectric conversion layer 142 is reduced.

[0097] In one embodiment, the specific dots are configured to intensify incoming rays of lights 13. In one embodiment, the specific dots comprise at least one convex lens. In one embodiment, the specific dots are configured to be manufactured as convex lens by the marking device.

[0098] The convex lens focuses multiple incoming rays of light 13 to pass through the optical receiving layer 141. The number of rays of light 13 reaching a portion of the photoelectric conversion layer 142 is increased.

[0099] In one embodiment, the specific dots are manufactured by damaging and / or removing at least one portion of the optical receiving layer, allowing more incoming rays of light passing through the optical receiving layer.

[0100] In one example the predefined manipulated pattern 21 allows portion of incoming rays of light 13, that were previously blocked either at the optical receiving layer 141 or at the photoelectric conversion layer 142 before manipulation. In some examples the optical receiving layer 141 or the photoelectric conversion layer 142 comprise attenuating or blocking elements that may be removed by the predefined manipulated pattern 21 .

[0101] In one embodiment, in one predefined manipulated pattern, some part of the predefined manipulated pattern on the optical receiving layer is configured to attenuate incoming rays of light, and other part of the predefined manipulated pattern is configured to intensify incoming rays of light.

[0102] In one embodiment, the marking device comprises a first marking device and a second marking device.

[0103] In one embodiment, the marking of the predefined manipulated pattern attenuating incoming rays of light is produced by the first marking device. The marking of predefined manipulated pattern intensifying incoming rays of light is produced by the second marking device.

[0104] In one embodiment, one predefined manipulated pattern comprises the specific dots produced by different marking devices for attenuating incoming rays of light and for intensifying incoming rays of light. The specific dots produced by the different marking devices are difficult to replicate, thereby increasing the security of predefined manipulated pattern.

[0105] In one embodiment, a type of the predefined manipulated pattern 21 is configured to be selected according to the intended use of the digital camera. Examples of the predefined manipulated pattern 21 are unique patterns, for example, a linear barcode, a two-dimensional QR code or any other patterns that users like, stored in a database. The manufacturing process and / or logistics between different manufacturing locations of the predefined manipulated pattern 21 , image sensor 14 and the camera 10 may comply with appropriate security standards.

[0106] FIG. 3 illustrates schematically one exemplary view of a video stream captured with the camera 10 having a first predefined manipulated pattern 21 . FIG. 4 illustrates schematically one exemplary view of a video stream captured with the camera 10 having a second predefined manipulated pattern 21 , as seen from the recipient of the video stream. The recipient’s screen 16 shows the video stream and the other party on the screen 16. In the example of FIG. 3, the first predefined manipulated pattern 21 comprises a linear barcode 22. In the example of FIG. 4, the second predefined manipulated pattern 21 comprises a QR code 23.

[0107] In one embodiment, the visual image, such as the predefined manipulated pattern 21 , is the QR code 23 placed on the screen 16. The recipient can verify the QR code 23 from the screen 16, as it may be used for a further security element that is linked to internet security framework. For example, the QR code 23 may indicate via a trusted third party that the video stream originates from a trusted camera, which is known to be installed onto a trusted computer. The QR code 23 as the optical identity marker may verify the hardware used by the other party. In one embodiment, the predefined manipulated pattern 21 comprises a grating. The grating comprises elongated, parallel elements that leave slots in between, allowing rays of light 13 to travel through. The grating may comprise security hologram technology. In one embodiment, the grating is configured to produce a spectrum by diffraction to the photoelectric conversion layer 142 of image sensor 14. In one embodiment, the grating is used to produce diffraction to the incoming rays of light 13 reaching the photoelectric conversion layer 142 of image sensor 14. In one embodiment, the grating provides various visual images that change according to the lighting conditions. In one embodiment, the grating provides an interference pattern to the photoelectric conversion layer 142 of image sensor 14. In one embodiment, the predefined manipulated pattern 21 comprises a point grating, causing a sinusoidal zone plate image onto the photoelectric conversion layer 142 of image sensor 14.

[0108] In one embodiment, the database comprises macroscopic scale information of the predefined manipulated pattern 21 . In one embodiment, the macroscopic scale information of the predefined manipulated pattern 21 comprises the form of a series of varying-width lines and spaces. In one embodiment, the macroscopic scale information comprises shape information of the predefined manipulated pattern 21 .

[0109] In one embodiment, the database comprises microscopic scale information of each pixel of the predefined manipulated pattern 21 . In one embodiment, the microscopic scale information comprises pixel values. One example of the pixel value is a brightness value of each specific dot of the markings of predefined manipulated pattern 21 .

[0110] In one embodiment, each macroscopic scale information and each microscopic scale information of the predefined manipulated pattern 21 are configured to be registered as the unique information in the database, which means each predefined manipulated pattern 21 has only one identifier in the database.

[0111] In one embodiment, a computer comprises the digital camera 10 having a predefined manipulated pattern 21. The predefined manipulated pattern 21 is configured to be visible on the digital image or the video stream by applying external light directly to the digital camera 10. In one embodiment, the example of the external light is a smartphone flashlight, or a hand-held electric torch. In one embodiment, the external light is configured to provide different colors to produce different visual effects on the image sensor 14.

[0112] In one embodiment, either party can verify the visual image from a screen 16 of the computer by a verification device or software. In one embodiment, the visual image is configured as the QR code 23 or the linear barcode 22.

[0113] In one embodiment, the verification device or the software is configured to scan the visual image showing on the screen 16 and to verify the authenticity of the microscopic scale information. In one embodiment, the database is configured to be stored in the verification device or in the software.

[0114] Through the verification device or the software, the scanned visual image is compared with the information stored in the database. When the information from the database and the information from the scanned visual image are matched with each other, the digital image or the video stream is verified successfully.

[0115] Detecting the visual images or effects caused by the predefined manipulated pattern 21 is on one embodiment executed by the verification device or the software comprising at least one processor and a memory storing instructions that, when executed, cause the verification device or the software to compare the visual image to predefined rules, comparative images, or other data to verify the authenticity.

[0116] FIG. 7a and 7b illustrate schematically one exemplary view of the predefined manipulated pattern 21 manufactured on the image sensor 21 by the multiplepulse laser and the single-pulse laser, captured with the photoelectric conversion layer 142.

[0117] In one embodiment, a first image 43 comprises a marking of the predefined manipulated pattern 21 manufactured by the multiple-pulse laser. A second image 33 comprises a marking of the predefined manipulated pattern 21 manufactured by the single-pulse laser. A third image as the single dot 53 comprises a marking of the predefined manipulated pattern 21 manufactured by the mechanical device. In one embodiment, when the digital camera 10 captures incoming rays of light 13, the specific dots on the optical receiving layer 141 , such as the first dots 31 , the second dots 42, or the single dots 53, are configured to attenuate or block incoming rays of the light 13 or allow to pass through less light compared to their surroundings. The digital image or video stream resulting from the attenuating process will appear darker at the positions corresponding to the specific dots on the optical receiving layer 141 .

[0118] In one embodiment, when the digital camera 10 captures incoming rays of light 13, the specific dots on the optical receiving layer 141 , such as the first dots 31 , the second dots 42, or the single dots 53, are configured to intensify incoming rays of the light 13 or allow to pass through more light compared to their surroundings. The digital image or video stream resulting from the intensifying process will appear brighter at the positions corresponding to the specific dots on the optical receiving layer 141 .

[0119] In one embodiment, each specific dot manufactured by a marking device has its unique feature. For example, the different depths, widths, or other properties. The number of incoming rays of light 13 passing through each specific dot is different, depending on the feature of each specific dot.

[0120] In one embodiment, the first dots 31 , the second dots 42, and the single dots 53 are configured to be divided into small grids. The features of each specific dot in each grid, as the pixel values, are configured as the fingerprints of the marking of the predefined manipulated pattern 21. Through the verification device or the software, the fingerprints of the predefined manipulated pattern 21 can be verified.

[0121] When the shapes of the predefined manipulated pattern 21 are the same or similar, the pixel values of the first dots 31 , the second dots 42 and the single dots 53 are configured as the fingerprints of the marking of the predefined manipulated pattern 21 , to be verified by the verification device or the software.

[0122] In one embodiment, the grid is configured to match the pixel level of the image sensor 14, wherein each grid corresponds to a single pixel. In one embodiment, the grid is configured to span multiple pixels. For example, one grid comprises two pixels or more.

[0123] FIG. 8 illustrates a flowchart of a method for marking information production. The marking information comprises the pixel values of each specific dot. In one embodiment, the flowchart comprises a process for converting the first dot 31 captured with the image sensor 14 to the pixel values, through the image processor.

[0124] In one embodiment, the first dot 31 is configured as one marking of the predefined manipulated pattern 21. The process is configured to determine the fingerprints of each marking of the predefined manipulated pattern 21. Each marking of the predefined manipulated pattern 21 will be processed in the same way, which means each marking of the predefined manipulated pattern 21 is converted to the pixel values following the process described above.

[0125] In one embodiment, pixel values of all specific dots of markings of the predefined manipulated pattern 21 are configured as the fingerprints of the markings of the predefined manipulated pattern 21 . The optical receiving layer 141 comprises the predefined manipulated pattern 21.

[0126] When the incoming rays of light 13 pass through the optical receiving layer 141 and reach the photoelectric conversion layer 142, the photoelectric conversion layer 142 captures the rays of light adjusted by the predefined manipulated pattern 21 , showing a negative image.

[0127] Step 60 comprises one first dot 31 captured with the predefined manipulated pattern 21 , which is displayed as a negative image.

[0128] In one embodiment, step 61 comprises an example of the first dot 31 being located on a 12 x 12-pixel matrix. In one embodiment, step 61 to step 64 comprises applying grayscale processing to the image of the first dot 31 and assigning a pixel value to each pixel. The pixel value, represented by a single number, indicates the pixel's brightness.

[0129] In one embodiment, the pixel values of the first dot 31 within the matrix are further normalized, allowing the pixel values to cover a range from 0 to 100. “0” represents the brightest value after converting the negative image to a positive image, while “100” represents the darkest value.

[0130] In one embodiment, step 64 comprises pixel values, which means the fingerprints of the first dot 31 of one marking of the predefined manipulated pattern 21 . The same method will be applied to all markings of the predefined manipulated pattern 21 , each marking of the predefined manipulated pattern 21 has their own unique fingerprints.

[0131] FIG. 9 illustrates one exemplary view of three-level encoding embedded in a predefined manipulated pattern 21. In one embodiment, each marking of the predefined manipulated pattern 21 comprises three-level encoding information. In one embodiment, the three-level encoding information is stored in the database. Level 1 to level 3 comprises an example of three-level encoding information embedded in the QR code 23. The QR code 23 is configured as one predetermined manipulation pattern 21 in this embodiment.

[0132] In one embodiment, level 1 comprises screen information of the predefined manipulated pattern 21 . Examples of the screen information are a QR code, a linear barcode, a web address, a unique pattern, or other suitable information. The screen information is configured to be available to the public as a priority. The video streams or images having the predefined manipulated pattern 21 captured with the digital camera 10 can be visually verified.

[0133] In one embodiment, level 2 comprises marking information. The marking information manufacturing process follows the steps of the flowchart described in FIG. 8. The pixel values of all markings of the predefined manipulated pattern 21 are stored in the database.

[0134] The specific dots of the markings of the predefined manipulated pattern 21 correspond to the pixel values. When the shapes of the predefined manipulated pattern 21 are the same or similar, the pixel values of all markings are configured as the fingerprints of the marking of the predefined manipulated pattern 21 ; thus, the image or video stream can be further verified by the verification device or the software. The marking information of the markings of the predefined manipulated pattern 21 is used to verify the authenticity of image or video stream. In one embodiment, level 3 comprises the size information. The size information comprises the distance between markings of the predefined manipulated pattern 21 , expressed in pixel values. The distance information of the markings of the predefined manipulated pattern 21 is used to verify the authenticity of image or video stream.

[0135] In one embodiment, the verification device or the software is configured to be used by institutions that require a higher level of authentication and information security. The predefined manipulated pattern 21 as the optical identity marker may be used to detect the hardware used in capturing the image, thereby ensuring the traceability of the communication from end-to-end.

[0136] FIG. 11 illustrates a flowchart of a method for manufacturing the optical identity marker. Step 71 comprises an image sensor, having a base layer 143, an optical receiving layer 141 and a photoelectric conversion layer 142. Step 72 comprises manipulating the optical receiving layer 141 by the marking device. In one embodiment, examples of the marking device are a laser engraver, an etching tool, or a printing tool. In one embodiment, step 73 comprises producing a predefined manipulated pattern 21 to the optical receiving layer 141 ; wherein the predefined manipulated pattern 21 is attenuating incoming rays of light 13 from reaching a portion of the photoelectric conversion layer 142 of the image sensor 14. In one embodiment, the predefined manipulated pattern 21 is intensifying incoming rays of light 13 from reaching a portion of the photoelectric conversion layer 142 of the image sensor 14.

[0137] In one embodiment, a laser beam from the marking device is configured to pass through a spatial light modulator (SLM), or a digital micro-mirror device (DMD). The predefined manipulated pattern 21 is configured to be manufactured on the optical receiving layer 141 by laser beams from the marking device. The SLM or the DMD is utilized to alter the phase and / or amplitude of the laser beam and modify the distribution of power inside the laser beam. The varying depths, widths, or other properties of the first dots 31 and the second dots 42 are configured to be controlled by directing the laser beams to pass through the SLM or the DMD. These may be used to provide random values to the predefined manipulated pattern 21. In one embodiment, the laser beam is configured to pass through a heated and ventilated plate. The hot and cold turbulent airflow around the plate, having different densities, influences the homogeneity of the laser beam in a non- controllable, random manner. The varying depths, widths, or other properties of the first dots 31 and the second dots 42 are configured to be controlled by directing the laser beams to pass through the heated and ventilated plate.

[0138] In one embodiment, the laser beam is configured to pass through a transparent container. The transparent container inside comprises air mixed with other gas, smoke, or dust in a turbulent airflow. The varying depths, widths, or other properties of the first dots 31 and the second dots 42 are configured to be controlled by directing the laser beams to pass the transparent container with mixed air.

[0139] The duration between two laser pulses can be adjusted, for example, from tens of picoseconds to hundreds of nanoseconds. The adjustment allows for changes in the phase and / or amplitude of the laser beam to occur between laser pulses.

[0140] The random factors or any other result caused by the image sensor manipulation may be measured from the completed image sensor. The database may store the actual measured values for each pixel from the image sensor.

[0141] As one aspect, an image sensor is disclosed herein, comprising a base layer; an optical receiving layer allowing incoming rays of light to pass through; and a photoelectric conversion layer configured to capture rays of light from the optical receiving layer and to generate digital signals. One aspect of this disclosure presents a novel optical receiving layer, wherein the optical receiving layer comprises a predefined manipulated pattern, wherein the predefined manipulated pattern is configured to adjust the number of incoming rays of light from reaching a portion of the photoelectric conversion layer. In one embodiment, the predefined manipulated pattern is configured to attenuate incoming rays of light passing through a silhouette defined by an outline of the predefined manipulated pattern. In one embodiment, the predefined manipulated pattern is configured to intensify incoming rays of light passing through a silhouette defined by an outline of the predefined manipulated pattern. In one embodiment, the predefined manipulated pattern comprises markings, engraved on the optical receiving layer by an engraving tool. In one embodiment, the engraving tool is a laser engraver. In one embodiment, the predefined manipulated pattern comprises markings, etched on the optical receiving layer by an etching tool. In one embodiment, the predefined manipulated pattern comprises markings, printed on the optical receiving layer by a printing tool.

[0142] Alternatively, or in addition, a digital camera is disclosed. The digital camera comprises an image sensor receiving incoming rays of light from a lens; and a cover glass for the image sensor on an optical path between the lens and the image sensor. A predefined manipulated pattern is configured on an optical receiving layer of the image sensor, wherein the predefined manipulated pattern is configured to adjust the number of incoming rays of light from reaching a portion of a photoelectric conversion layer of the image sensor. In one embodiment, the predefined manipulated pattern is configured to attenuate incoming rays of light passing through a silhouette defined by an outline of the predefined manipulated pattern. In one embodiment, the predefined manipulated pattern is configured to intensify incoming rays of light passing through a silhouette defined by an outline of the predefined manipulated pattern.

[0143] Alternatively, or in addition, a method for manufacturing an optical identity marker. The method comprises an image sensor having a base layer, an optical receiving layer, and a photoelectric conversion layer. The method comprises manipulating the optical receiving layer by a marking device; and producing a predefined manipulated pattern to the optical receiving layer; wherein the predefined manipulated pattern is adjusting the number of incoming rays of light from reaching a portion of the photoelectric conversion layer of the image sensor. In one embodiment, the method comprises by predefined manipulated pattern, attenuating or intensifying incoming rays of light passing through a silhouette defined by an outline of the predefined manipulated pattern. In one embodiment, the method comprises engraving markings of the predefined manipulated pattern to the optical receiving layer by a laser engraver. In one embodiment, the method comprises etching markings of the predefined manipulated pattern to the optical receiving layer by an etching tool. In one embodiment, the method comprises printing markings of the predefined manipulated pattern to the optical receiving layer by a printing tool.

[0144] Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware components or hardware logic components. An example of the device described hereinbefore is a computingbased device comprising one or more processors which may be microprocessors, controllers, or any other suitable type of processors for processing computer-executable instructions to control the operation of the device in order to control one or more sensors, receive sensor data and use the sensor data. The computer-executable instructions may be provided using any computer-readable media that is accessible by a computing-based device. One example of the computing-based device is arranged in a cloud computing environment. Computer-readable media may include, for example, computer storage media such as memory and communications media. Computer storage media, such as memory, includes volatile and non-volatile, removable, and nonremovable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, SSD drives, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices or any other non-transmission medium that can be used to store information for access by a computing device. In contrast, communication media may embody computer-readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave, or other transport mechanism. As defined herein, computer storage media does not include communication media. Therefore, a computer storage medium should not be interpreted to be a propagating signal per se. Propagated signals may be present in a computer storage media, but propagated signals per se are not examples of computer storage media. Although the computer storage media is shown within the computing-based device, it will be appreciated that the storage may be distributed or located remotely and accessed via a network or other communication link, for example, by using a communication interface.

[0145] The apparatus or the device may comprise an input / output controller arranged to output display information to a display device which may be separate from or integral to the apparatus or device. The input / output controller is also arranged to receive and process input from one or more devices, such as a user input device (a mouse, keyboard, camera, microphone, or other sensor). Examples of the apparatus or the device are smartphones, laptops, or tablet computers.

[0146] The methods described herein may be performed by a software in machine- readable form on a tangible storage medium in the form of a computer program comprising computer program code means adapted to perform all the steps of any of the methods described herein when the program is run on a computer and where the computer program may be embodied on a computer-readable medium. Examples of tangible storage media include computer storage devices comprising computer-readable media, such as disks, thumb drives, memory etc. and do not only include propagated signals. Propagated signals may be present in a tangible storage media, but propagated signals per se are not examples of tangible storage media. The software can be suitable for execution on a parallel processor or a serial processor such that the method steps may be carried out in any suitable order, or simultaneously.

[0147] Any range or device value given herein may be extended or altered without losing the effect sought.

[0148] Although at least a portion of the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter defined in the accompanying claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

[0149] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to ‘an’ item refers to one or more of those items.

[0150] The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate. Additionally, individual blocks may be deleted from any of the methods without departing from the spirit and scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

[0151] The term ‘comprising’ is used herein to mean including the method blocks or elements identified, but that such blocks or elements do not comprise an exclusive list and a method or device may contain additional blocks or elements.

[0152] It will be understood that the above description is given by way of example only and that various modifications may be made by those skilled in the art. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments. Although various embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this specification.

Claims

CLAIMS1. An image sensor (14) for a digital camera (10), comprising: a base layer (143); an optical receiving layer (141) allowing incoming rays of light (13) to pass through; and a photoelectric conversion layer (142) configured to capture rays of light from the optical receiving layer (141) and to generate digital signals; characterized in that: the optical receiving layer (141) comprises a predefined manipulated pattern (21), wherein the predefined manipulated pattern (21) is configured to adjust the number of incoming rays of light (13) from reaching a portion of the photoelectric conversion layer (142).

2. An image sensor (14) according to claim ^characterized in that the predefined manipulated pattern (21) is configured to attenuate incoming rays of light (13) passing through a silhouette defined by an outline of the predefined manipulated pattern (21).

3. An image sensor (14) according to claim ^characterized in that the predefined manipulated pattern (21) is configured to intensify incoming rays of light (13) passing through a silhouette defined by an outline of the predefined manipulated pattern (21).

4. An image sensor (14) according to any of the claims 1 to 3, characterized in that the predefined manipulated pattern (21 ) comprises markings, engraved on the optical receiving layer (141) by an engraving tool.

5. An image sensor (14) according to claim 4, characterized in that the engraving tool is a laser engraver.

6. An image sensor (14) according to any of the claims 1 to 3, characterized in that the predefined manipulated pattern (21 ) comprises markings, etched on the optical receiving layer (141) by an etching tool.

7. An image sensor (14) according to any of the claims 1 to 3, characterized in that the predefined manipulated pattern (21 ) comprises markings, printed on the optical receiving layer (141) by a printing tool.

8. A digital camera (10), comprising: an image sensor (14) receiving incoming rays of light (13) from a lens (11); and a cover glass (12) for the image sensor (14) on an optical path between the lens (11 ) and the image sensor (14); characterized in that: a predefined manipulated pattern (21) is configured on an optical receiving layer (141) of the image sensor (14), wherein the predefined manipulated pattern (21) is configured to adjust the number of incoming rays of light (13) from reaching a portion of a photoelectric conversion layer (142) of the image sensor (14).

9. A digital camera (10) according to claim 8, characterized in that the predefined manipulated pattern (21) is configured to attenuate incoming rays of light (13) passing through a silhouette defined by an outline of the predefined manipulated pattern (21).

10. A digital camera (10) according to claim 8, characterized in that the predefined manipulated pattern (21) is configured to intensify incoming rays of light (13) passing through a silhouette defined by an outline of the predefined manipulated pattern (21).

11. A method for manufacturing an optical identity marker,having an image sensor comprising a base layer (143), an optical receiving layer (141) and a photoelectric conversion layer (142); characterized by: manipulating the optical receiving layer (141) by a marking device; and producing a predefined manipulated pattern (21) to the optical receiving layer (141); wherein the predefined manipulated pattern (21) is adjusting the number of incoming rays of light (13) from reaching a portion of the photoelectric conversion layer (142) of the image sensor (14).

12. A method according to claim 11, characterized by predefined manipulated pattern (21), by attenuating or intensifying incoming rays of light (13) passing through a silhouette defined by an outline of the predefined manipulated pattern (21).

13. A method according to claim 11 or claim 12, characterized by engraving markings of the predefined manipulated pattern (21) to the optical receiving layer (141) by a laser engraver.

14. A method according to claim 11 or claim 12, characterized by etching markings of the predefined manipulated pattern (21) to the optical receiving layer (141) by an etching tool.

15. A method according to claim 11 or claim 12, characterized by printing markings of the predefined manipulated pattern (21) to the optical receiving layer (141) by a printing tool.

Images