Redundant two-dimensional code and a decoding method
In order to reduce a two-dimensional data structure to a minimum number of bits, a two-dimensional surface pattern is provided, which can be used in particular for identifying an absolute position on the surface and which has a pattern which comprises a SYNC pattern, which is used for synchronization, and a position-dependent code PC(x, y), with the SYNC pattern being variable and being formed in accordance with an already known formation rule.
1. A two-dimensional surface pattern, in particular for identifying an absolute position on the surface, comprising
a pattern ( 1 ),
the pattern ( 1 ) containing a SYNC pattern ( 2 ), which is used for synchronization, and a position-dependent code PC (x, y),
wherein
the SYNC pattern ( 2 ) is variable and is formed in accordance with an already known formation rule, wherein the pattern has a modulation, and wherein said modulation comprises amplitude modulation.
2. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the SYNC pattern ( 2 ) comprises two variable components ( 21 , 22 ), which are each used for synchronization along two directions, which are not parallel, on the surface.
3. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the SYNC pattern ( 2 ) is distributed geometrically uniformly over the surface.
4. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the SYNC pattern ( 2 ) has a position-dependent code.
5. The two-dimensional surface pattern as claimed in claim 1 , with the SYNC pattern ( 2 ) comprising the least significant bit of the position-dependent code PC(x, y).
6. The two-dimensional surface pattern as claimed in claim 1 ,
wherein components of the pattern are combined in one unit of the code, which code unit ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ), preferably comprises a square or hexagonal shape.
7. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the SYNC pattern ( 2 ) occurs at least twice a position frequency in the x and y directions in comparison to the position-dependent code of the position-dependent code PC(x, y).
8. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the surface pattern comprises a document identifier DI.
9. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the SYNC pattern ( 2 ) comprises parts of the document identifier.
10. The two-dimensional surface pattern as claimed in claim 1 ,
wherein at least one of the position-dependent code PC(x, y) and document identifier, DI, is redundantly coded.
11. The two-dimensional surface pattern as claimed in claim 1 ,
wherein a function which describes neighborhood relationships to other adjacent code units ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) is associated with the position-dependent code PC(x, y).
12. The two-dimensional surface pattern as claimed in claim 11 ,
wherein others of the position-dependent codes PC (x, y) are calculatable from the position-dependent code PC (x, y) of a known code unit ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) by means of the function which is associated with the position-dependent code PC (x, y).
13. The two-dimensional surface pattern as claimed in claim 11 ,
wherein the position-dependent code PC (x, y) of all adjacent code units ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) are calculatable from a single position-dependent code PC (x, y) by means of the function which is associated with the position-dependent code PC (x, y).
14. The two-dimensional surface pattern as claimed in claim 1 ,
wherein a sequence of the code units ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) on the surface is scrambled in any desired direction on the surface.
15. The two-dimensional surface pattern as claimed in claim 1 ,
wherein a size of a code unit ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) in one direction on the surface is 4 mm.
16. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the shape elements ( 11 , 12 ) comprise squares, triangles, circles or dots.
17. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the modulation comprises phase modulation, PSK, in which shape elements ( 11 , 12 ), in particular dots, are arranged shifted with respect to a reference grid.
18. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the modulation comprises frequency modulation, FSK, in which groups of shape elements ( 11 , 12 ) are arranged at predefined 2D position frequencies on the surface.
19. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the pattern has more than one color, in particular more than one spectrally separable component, and one spectrally separable component has a different modulation than another spectrally separable component.
20. The two-dimensional surface pattern as claimed in claim 19 ,
wherein the spectrally separable components cover the IR spectrum and, in particular,
IR/fluorescence bands of colors which are excitable and are printable on the surface.
21. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the surface pattern ( 1 ) is printed on an adhesive strip.
22. The two-dimensional surface pattern as claimed in claim 1 ,
wherein the surface pattern ( 1 ) is subdivided into a number of parts.
23. The two-dimensional surface pattern as claimed in claim 22 ,
wherein the parts are located separately from one another on at least one surface.
24. The two-dimensional surface pattern as claimed in claim 1 , which has a light/dark pattern of shape elements ( 11 , 12 ).
25. A method for decoding data in an area of a surface pattern, with the surface pattern containing a variable SYNC pattern ( 2 ), which is used for synchronization and is formed in accordance with an already known formation rule, as well as a position-dependent code PC(x, y), with the SYNC pattern ( 2 ) comprising the least significant bit of the position-dependent code PC (x, y), and whereby a code unit consists of a 6×6 bits, wherein a complete position-dependent code which is associated with one position on the surface pattern can always be decoded from the area ( 6 ) of the surface pattern ( 1 ), in that parts of adjacent position-dependent codes which are located in that area of the surface pattern are used to supplement missing parts of the position-dependent code for decoding.
26. The method as claimed in claim 25 , wherein the area ( 6 ) of the surface pattern is so small that at most one position-dependent code which is associated with one position on the surface pattern may be present completely within the area ( 6 ).
27. The method for decoding as claimed in claim 26 , wherein the area ( 6 ) of the surface pattern has any desired shape.
28. The method as claimed in claim 26 , wherein components of the pattern are combined in one unit of the code, a code unit ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) and the area ( 6 ) is so small that at most one code unit ( 3 , 31 , 32 , 33 , 34 , 35 , 36 ) is located completely in the area.