Abstract
The present invention relates to a method of concurrently storing visible grey scale or color information of an image and additional digital information on a data carrier.
Claims
1-53. (canceled)
54. A method of concurrently storing grey scale information of an image and additional digital information, comprising: providing a data carrier; and creating a plurality of recesses in a surface of the data carrier by using a laser and/or a focused particle beam in order to encode information on the data carrier; wherein the plurality of recesses are grouped in pixels forming an image, each pixel comprising between zero and M recesses located at a subset of zero to M positions of N predetermined positions attributed to the pixel, wherein the number of recesses of a given pixel defines a visual grey scale value of the pixel and wherein the subset of positions of a given pixel defines additional digital information attributed to the pixel, wherein the additional digital information comprises one or a combination of: a more precise grey scale value of the pixel, a color or color value of the pixel, an intensity of any of the colors red, green and blue of the pixel.
55. The method of claim 54, wherein each pixel has an area of at most 1 ?m.sup.2.
56. The method of claim 54, wherein the additional digital information further comprises one or a combination of: a letter, a number, a symbol, audio information, video information.
57. The method of claim 54, wherein providing the data carrier comprises providing a substrate and coating the substrate with a first coating of a material different from a material of the substrate; and wherein creating the plurality of recesses in the surface of the data carrier comprises creating the plurality of recesses in the first coating.
58. The method of claim 57, wherein the recesses extend through the coating towards the substrate.
59. The method of claim 57, wherein the substrate is a ceramic substrate.
60. The method of claim 57, wherein the substrate comprises a glassy transparent ceramic material or a crystalline ceramic material.
61. The method of claim 57, wherein the substrate comprises one or a combination of: sapphire (Al.sub.2O.sub.3), silica (SiO.sub.2), zirconium silicate (Zr(SiO.sub.4)), ZrO.sub.2, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide.
62. The method of claim 57, wherein the substrate has a thickness of at most 100 ?m.
63. The method of claim 54, wherein a visual grey scale of the image defined by the pixels is discernable by the naked eye or by means of refractive, diffractive or reflective optical elements without further processing in either reflection or transmission.
64. The method of claim 54, wherein single recesses of each pixel are not discernable by the naked eye.
65. The method of claim 54, further comprising creating multiple allocation elements which allow for allocating certain areas of the data carrier to the pixels.
66. The method of claim 65, wherein the allocation elements are created by a plurality of recesses different from the recesses of each pixel.
67. The method of claim 65, wherein the allocation elements comprise horizontal and/or vertical lines.
68. A method of reading out additional digital information from an image formed of pixels stored on a data carrier, wherein each pixel of the image comprises between zero and M recesses located at a subset of zero to M positions of N predetermined positions attributed to the pixel, the method comprising: identifying, for each pixel, the subset of positions at which a recess is present; and attributing a predetermined information to each pixel in accordance with the identified subset of the positions at which a recess is present, wherein the predetermined information comprises one or a combination of: a grey scale value of the pixel, a color or color value of the pixel, an intensity of any of the colors red, green and blue of the pixel.
69. The method of claim 68, wherein the data carrier comprises multiple allocation elements which allow for allocating certain areas of the data carrier to the pixels, the method further comprising identifying the allocation elements and identifying the pixels based on the identified allocation elements.
70. A method of concurrently storing RGB color information of an image and additional digital information, the method comprising the steps of: providing a data carrier; and creating a plurality of recesses in a surface of the data carrier by using a laser and/or a focused particle beam in order to encode information on the data carrier; wherein the plurality of recesses are grouped in pixels forming an image, wherein NR+NG+NB predetermined positions are attributed to each pixel, the NR+NG+NB predetermined positions comprising NR predetermined R positions, NG predetermined G positions and NB predetermined B positions, wherein each pixel comprises between zero and MR recesses located at a subset of zero to MR positions of the NR predetermined R positions, wherein each pixel comprises between zero and MG recesses located at a subset of zero to MG positions of the NG predetermined G positions, wherein each pixel comprises between zero and MB recesses located at a subset of zero to MB positions of the NB predetermined B positions, wherein the number of recesses at the predetermined R positions, nR, of a given pixel defines an intensity of the color red, wherein the number of recesses at the predetermined G positions, nG, of a given pixel defines an intensity of the color green, wherein the number of recesses at the predetermined B positions, nB, of a given pixel defines an intensity of the color blue, and wherein the subset of zero to MR positions, the subset of zero to MG positions, and/or the subset of zero to MB positions of a given pixel defines additional digital information attributed to the pixel.
71. The method of claim 70, wherein NR, NG, and/or NB is at least 4.
72. The method of claim 70, wherein NR is equal to or greater than NG and/or NB.
73. The method of claim 70, wherein the additional digital information comprises one or a combination of: a more precise intensity of any of the colors red, green and blue attributed to the pixel, another color or color value attributed to the pixel, a letter, a number, a symbol, audio information, video information.
74. The method of claim 70, wherein providing the data carrier comprises providing a substrate and coating the substrate with a first coating of a material different from a material of the substrate; and wherein creating the plurality of recesses in the surface of the data carrier comprises creating the plurality of recesses in the first coating.
75. The method of claim 70, further comprising creating multiple allocation elements which allow for allocating certain areas of the data carrier to the pixels.
76. The method of claim 75, wherein the allocation elements are created by a plurality of recesses different from the recesses of each pixel.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The present invention will be further elucidated with reference to the Figures, which show:
[0042] FIG. 1a a graph showing the number of permutations for zero to 16 recesses on 16 predetermined positions;
[0043] FIG. 1b a scheme for attributing 256 digital permutations to 17 analog grey values;
[0044] FIGS. 2a-2c a grey scale image exemplifying the technique of the present invention;
[0045] FIGS. 3a and 3b a scheme for attributing RGB color information of a color pixel to a pattern of recesses which result in a visible grey scale pixel;
[0046] FIG. 3c an example of a scheme for identifying pixels on a data carrier;
[0047] FIG. 4 a cross section through a data carrier encoded with a grey scale image;
[0048] FIGS. 5a and 5b cross sections through a data carrier encoded with a color image utilizing a photoluminescent layer;
[0049] FIG. 6 schematically a first decoding method;
[0050] FIG. 7 schematically a second decoding method;
[0051] FIG. 8 schematically a third decoding method;
[0052] FIG. 9 a device for writing and reading out additional digital information from an image stored on a data carrier;
[0053] FIG. 10 a device for writing and reading out additional digital information from an image stored on a data carrier;
[0054] FIG. 11 a device for writing and reading out additional digital information from an image stored on a data carrier; and
[0055] FIG. 12 a device for writing and reading out additional digital information from an image stored on a data carrier.
DETAILED DESCRIPTION
[0056] FIG. 1a shows the number of possible permutations for zero to 16 recesses on 16 predetermined positions, exemplified for a square 4?4 matrix. For each number of recesses between zero and 16 one exemplary arrangement of recesses (or white fields) is illustrated. While there is only one option to have no recess (left end) or 16 recesses (right end) present in one pixel, a single recess or 15 recesses may be arranged in 16 different ways. By contrast, there are 12,870 permutations possible for placing 8 recesses onto 16 predetermined positions. The number of permutations may generally be calculated as N!/[(N?M)!M!], where N is the number of predetermined positions and M is the number of recesses.
[0057] FIG. 1b shows an exemplary scheme for attributing additional digital information to pixels corresponding to a certain grey scale value. In FIG. 1b, 17 analog grey scale values are displayed changing from black (left end) to white (right end). Since black and white each allow for a single permutation only, this has to be compensated if a total of 256 digital permutations (8 bit) are required. In the example of FIG. 1b, this is achieved by providing 17 different permutations wherever possible and 18 permutations for the case of 8 recesses. Thus, a total of 2?1+2?16+12?17+1?18=256 permutations, i.e. 8 bit, are possible. Of course, other arrangements would be possible as well even though a symmetrical allocation of digital grey scale values to the analog grey scale values is preferable. Moreover, as is evident from FIG. 1a, one could also store 512 or 1024 permutations (i.e., 9 or 10 bit) in the 4?4 pixels utilizing a more asymmetric allocation.
[0058] The present invention is now based on the idea that each row of the scheme shown in FIG. 1b, i.e. the number of recesses of a given pixel, defines an analog grey scale value of said pixel (schematically shown at the bottom of FIG. 1b) and that the subset of positions of a given pixel (i.e., the specific permutation pattern) defines additional digital information attributed to said pixel (e.g. one out of 256 digital grey scale values). This is exemplary shown in FIGS. 2a-c. FIG. 2a shows a digital grey scale image and two magnified sections at different magnification, the right one showing different pixels having different grey scales. In FIG. 2b, each pixel is replaced by a pixel in accordance with FIG. 1b (middle), the blurry version of which (right) corresponding to a 4 bit grey scale image having less quality than the original. However, on the basis of the additional digital information being present on a microscopic level, the high quality grey scale image may again be reconstructed (FIG. 2c).
[0059] As outlined above, this concept may also be employed for color images, as schematically shown in FIGS. 3a-3c. The plurality of recesses in this case are grouped in square pixels (one of which is shown in FIG. 3a) forming an image with each recess again being depicted as a white square, wherein 3?27 predetermined positions are attributed to each pixel, said 3?27 predetermined positions comprising 27 predetermined R positions (arranged in a 3?9 pattern), 27 predetermined G positions and 27 predetermined B positions. Each pixel comprises between zero and 27 (here: 8) recesses located at a subset of zero to 27 positions of the 27 predetermined R positions. Furthermore, each pixel comprises between zero and 27 (here: 15) recesses located at a subset of zero to 27 positions of the 27 predetermined G positions. Moreover, each pixel comprises between zero and 27 (here: 23) recesses located at a subset of zero to 27 positions of the 27 predetermined B positions. The number of recesses at predetermined R positions, nR, of a given pixel defines an intensity of the color red, the number of recesses at predetermined G positions, nG, of a given pixel defines an intensity of the color green, and the number of recesses at predetermined B positions, nB, of a given pixel defines an intensity of the color blue. The subset of R positions and/or the subset of G positions and/or the subset of B positions of a given pixel defines additional digital information attributed to said pixel.
[0060] Now, if the pixel shown at the bottom of FIG. 3a is, for example, illuminated with red, green and blue light in the corresponding pixel sections (here: three vertical stripes) as shown at the top of FIG. 3b, said pixel emits light with red, green and blue intensities according to the numbers of R, G and B positions (here: 8, 15 and 23). Viewed from a proper distance said pixel will appear to have one uniform, mixed color (here: mid blue) as schematically shown at the bottom of FIG. 3b. However, the microstructure of the pixel, i.e. the subset of R positions and the subset of G positions and the subset of B positions will allow for reconstructing a high resolution color image.
[0061] Of course, when reading out the additional digital information encoded on the data carrier, it will be required to identify the pixels containing said additional digital information, which may be difficult if one imagines, for example, the various permutations shown in FIG. 1b to be arranged immediately adjacent to one another. It is thus preferred that the data carrier comprises multiple allocation elements which allow a reading device or a processor to allocate certain areas of the data carrier to pixels. FIG. 3c shows an example of such allocation elements for identifying pixels on a data carrier.
[0062] The first two images of FIG. 3c show a parrot and its eye, respectively. Zooming in further, the third image of FIG. 3c (showing only the pupil and a part of the eye) gives the impression of an underlying square pattern, which is more clearly visible in the further magnifications of the fourth and fifth image of FIG. 3c. As is evident from the fifth image, the recesses on the data carrier form continuous vertical lines in black (i.e. continuous lines without any recess) as well as continuous horizontal lines in white (i.e. continuous lines of recesses) interrupted only by the continuous vertical lines in black. These lines are easily discernable by the human eye (or similarly an AI or other algorithm utilized in the processor of the reading device) and clearly define each pixel as having two black vertical and two white horizontal boundaries.
[0063] Of course, other allocation elements are envisaged as well. For example, each pixel may be identified by four corners. Alternatively, another large scale pattern might be utilized. For example, a repeating pattern of a pair of a completely white pixel and a completely black pixel may be provided.
[0064] FIG. 4 shows a cross section through an exemplary data carrier 12, on which grey scale information of an image and additional digital information is stored. In the example, the data carrier 12 comprises a substrate 20 and a coating 21. Recesses 22 extend through the entire thickness of the coating 21. If there is optical contrast between the substrate 20 and the coating 21, the recesses 22 will create a different optical impression in reflection mode than the coating. Moreover, if the substrate 20 is transparent, the encoded image may also be visible in transmission mode. As discussed above, the recesses 22 may be arranged in pixels such as those of the scheme shown in FIG. 1b in order to encode additional digital information.
[0065] FIG. 5a shows a cross section through another exemplary data carrier 12 comprising a substrate 20 and a coating 21 with recesses 22 similar to those of FIG. 4. However, in case of FIG. 5a, an additional photoluminescent layer 23 is present. Said photoluminescent layer 23 comprises different sections 23a, 23b and 23c having emission wavelengths in the red, green and blue spectrum, respectively. Accordingly, if the data carrier shown in FIG. 5a is illuminated with white light, recesses 22 positioned above sections 23a of the photoluminescent layer 23 will appear red. Similarly, recesses 22 positioned above sections 23b or 23c of the photoluminescent layer 23 will appear green or blue. Of course, this requires the data carrier 20 to be transparent. Moreover, it will be evident to the skilled person that the sections 23a, 23b and 23c of the photoluminescent layer 23 of the data carrier 12 have to be properly registered with the predetermined R, G and B positions. For example, the sections 23a, 23b and 23c could be elongated stripes extending along the entire length of the data carrier with the width of each stripe corresponding to one third of the width of the pixel (see FIG. 3b). Yet, other arrangements would of course also be possible.
[0066] As shown in FIG. 5b, the photoluminescent layer 23 may also be arranged between the substrate 20 and the coating 21. In this case, reading out may also be possible in reflection mode.
[0067] FIG. 6 schematically shows a first decoding method for decoding the data carrier shown in FIGS. 5a and 5b. In FIG. 6, the data carrier 12 of FIG. 5a is shown upside down with the photoluminescent layer 23 above the transparent data carrier 20 and the coating 21 being arranged at the bottom. However, the data carrier 12 could, of course, also be decoded in the orientation shown in FIG. 5a. If the data carrier 12, as schematically shown in FIG. 6, is illuminated with white light from the top, the different sections 23a, 23b and 23c of the photoluminescent layer 23 will, due to their different photoluminescent properties, emit red, green and blue light, respectively. Said colored light is transmitted through the transparent substrate 20 and absorbed by the coating 21 wherever no recess 22 is present. However, at each recess position the light emitted from the section of the photoluminescent layer 23 being arranged directly above said recess 22 will be visible on the bottom side of the data carrier 12. As discussed above with respect to FIG. 3b, the various recesses of different color will give a merged color impression to the human eye (similar to the effect of an RGB display) and create the color image encoded on the data carrier.
[0068] As outlined above, this process of encoding color information is technically ambitious as a proper registration between the various photoluminescent sections and corresponding pixel regions has to be ensured. Accordingly, it may be preferable to generate the colored light externally rather than in the data carrier itself. For this purpose, a data carrier 12 as shown in FIG. 4 may be utilized, which data carrier 12 merely comprises a transparent substrate 20 and a coating 21 with recesses 22. Again, these recesses 22 are arranged in pixels as shown in FIGS. 3a and 3a in order to encode color information. As explained above with regard to FIG. 6, the color information encoded in those pixels may again be extracted by illuminating the R, G and B sections of each pixel with red, green and blue light. In the decoding method schematically shown in FIG. 7, said colored light is generated by an RGB display 24 illuminating this data carrier 12 with a pattern of red, green and blue light sections 24a, 24b and 24c. In the example shown in FIG. 7, these sections 24a, 24b and 24c form continuous lines or stripes extending along the entire length of the display 24 in accordance with the pixel arrangement shown in FIG. 3b. If the data carrier 12 is now illuminated with the RGB display 24 by means of suitable optics 25, red, green and blue light will pass through respective recesses 22 in the coating 21. Accordingly, red, green and blue light will be emitted from the bottom of the data carrier 12 and the red, green and blue light from each pixel will again merge to a uniform color for each pixel, thus generating a color image to the human eye.
[0069] Of course, proper registration is again required which, however, in the case of FIG. 7 may be achieved in a much more simple way as the data carrier 12 can simply be translated and/or rotated with respect to the RGB display until a proper image is formed. For this purpose, the data carrier may contain one or more alignment sections which will only generate a predetermined color pattern once proper registration has been achieved.
[0070] Finally, the color image encoded on the data carrier 12 may also be decoded without any colored light as schematically shown in FIG. 8. Again, the same data carrier 12 utilized in case of FIG. 7 may be used and illuminated with any illumination, e.g. with white light. The pattern of recesses 22 visible on the other side of the data carrier may be imaged by means of suitable optics 25 and a suitable image detector (such as a CCD camera) 26 in order to record the particular recess pattern of each pixel. Since a particular color value is allocated to each subset of recess positions of a given pixel (see FIG. 1b), the encoded color information can be extracted and, for example, displayed by means of a digital decoder and a corresponding display.
[0071] FIG. 9 shows a more elaborate device for reading out additional digital information from an image stored on a data carrier. Said device may also be used for high-speed recording data on the data carrier. FIG. 9 is almost identical to FIG. 1 of PCT Application Publication WO 2022/033701, the context of which is incorporated in its entirety by reference.
[0072] The device comprises a laser source 1, a motorized attenuator 3a, a beam expander 2, an attenuation rotator 3b, a flat top beam shaper (preferably including collimating optics) 14, a galvanometer scanner 4, a digital micromirror device (DMD) 5 adapted to emit multiple laser beams (of which only a single one is shown for simplicity), a beam dump 6, beam shaping optics 7, a semi-transparent mirror 8 and focusing optics 9 adapted for focusing each of the multiple laser beams emitted by the DMD 5 onto the coating 21 of a not yet encoded data carrier 12.
[0073] The galvanometer scanner 4 is configured to temporally distribute the laser power of the laser source 1 over the DMD 5. As explained in detail in PCT Application Publication WO 2022/033701, the galvanometer device 4 is configured to simultaneously illuminate only a section of the micromirror array of the DMD 5. Since the angle of the laser beam emitted from the galvanometer scanner 4 depends on the position or area on the DMD 5 which the galvanometer scanner 4 aims at, the device preferably comprises collimating optics L1, L2 in order to align the laser light emitted by the galvanometer scanner 4 to a predetermined entrance angle with respect to the DMD 5. In order to properly illuminate the galvanometer scanner 4 by means of the laser source 1 a motorized attenuator 3a, a beam expander 2, an attenuation rotator 3b, and a flat top beam shaper (preferably including collimating optics) 14 may be provided.
[0074] The DMD 5 comprises multiple micromirrors arranged in an array (not shown) and is adapted to emit multiple laser beams (not shown) along either a first direction (i.e., for recording) or along a second direction for each micromirror being in an off state diverting those laser beams into a beam dump 6. For each micromirror being in an on state, a laser beam is emitted via a beam splitter 8 through a focusing optics 9 which may, for example, comprise standard microscope optics having a high numerical aperture, onto the coating 21 being optionally mounted on an XY positioning system (which may optionally also be movable along the Z direction).
[0075] The device may further comprise beam shaping optics 7 such as a matrix of laser zone plates or a spatial light modulator, which may be configured to allow for optical proximity control, to generate Bessel beams, or to create a phase-shift mask.
[0076] In the embodiment shown in FIG. 9, the device further comprises a reading device 26 configured to image the recorded data and to, in particular, read out and/or display the additional digital information from an image stored on a data carrier 12. The reading device in this embodiment comprises a high-resolution digital camera for imaging the light transmitted through the recesses of the data carrier.
[0077] In the embodiment shown in FIG. 9, the data carrier 12 is illuminated from the backside with white light. The white light impinges on the RGB array of photoluminescent or fluorescent materials, thus creating an emission pattern of red, green and blue light. Said light passes through the transparent substrate 20 of the data carrier 12 and is blocked by the non-transparent coating 21 of the data carrier. However, wherever a recess 22 is present, the corresponding red, green or blue light passes through the coating 21 and via the focusing optics 9 onto the chip of, e.g., the CCD camera of the reading device 26. Thus, a high resolution color image may be collected by the CCD camera, which image may be displayed or used otherwise.
[0078] A similar device is shown in FIG. 10 with the white light source being replaced by an RGB display 24. This set-up allows for generating a color image without the need of a photoluminescent or fluorescent layer being present in the data carrier 12, as discussed above.
[0079] Finally, a digital coloring is schematically depicted in FIG. 11, which again utilizes homogenous illumination from the backside. In this embodiment, the subset of recesses is identified by each pixel and a predetermined color information is attributed to each pixel in accordance with the identified subset of positions at which a recess is present which attributed information is then used to digitally color the image, as schematically shown in FIG. 11.
[0080] FIG. 12 shows a further device for writing and reading out additional digital information from an image stored on a data carrier which is analog to the device shown in FIG. 11. However, in case of FIG. 12 the reading mode is performed in reflection mode rather than in transmission mode. Illumination during read-out is performed by means of an additional light source 17.
