Sparse modulation for robust signaling and synchronization
Sparse signal modulation schemes encode a data channel on a substrate in a manner that is robust, flexible to achieve perceptual quality constraints, and provides improved data capacity. The substrate is printed by any of a variety of means to apply the image, with sparse signal, to an object. After image capture of the object, a decoder processes the captured image to detect and extract data modulated into the sparse signal. The sparse signal may incorporate implicit or explicit synchronization components, which are either formed from the data signal or are complementary to it.
1. An image processing method for updating a design file for a retail product package or for a product label, said image processing method comprising:
obtaining a design file comprising a first area and a second area, the first area comprising area that is devoid of image or color variability, the second area comprising text;
using one or more multi-core processors, generating a sparse pattern of elements at spatial coordinates within the first area, the sparse pattern of elements conveying a machine-readable variable data signal, the sparse pattern of elements comprising a plurality of binary one and binary zero elements, which correspond to ink elements and no-ink elements of the sparse pattern of elements;
selecting an ink color to use for the ink elements through a perceptual analysis that minimizes a visual difference between the ink color and the first area, in which said selecting yields a selected ink color; and
providing the sparse pattern of elements and the selected ink color to update the design file.
2. The image processing method of claim 1 in which said generating comprises transforming a signal component to carry the variable data signal, in which the signal component comprises synchronization information.
3. The image processing method of claim 2 in which the signal component is converted to the sparse pattern of elements by removing signal elements of the signal component at spatial coordinates where the signal component does not coincide with spatial coordinates of the variable data signal.
4. The image processing method of claim 2 wherein the signal component is repeated in two-dimensional blocks within the first area, and different sparse patterns are used to distribute the signal component in plural of two-dimensional blocks.
5. The image processing method of claim 1 further comprises varying a signal amount at each of the ink elements.
6. The image processing method of claim 1 further comprising determining a dot shape or signal amplitude at a dot for the sparse pattern of elements.
7. The image processing method of claim 1 further comprising determining a bump shape at a location associated with a region of elements within the sparse pattern of elements.
8. The image processing method of claim 1 in which the first area comprises a blank area.
9. The image processing method of claim 1 in which the first area comprises a uniform color tone.
10. The image processing method of claim 1 in which said generating comprises selecting elements for the sparse pattern of elements at spatial coordinates where signal elements of the variable data signal and signal elements of a synchronization component have consistent signal values or fall within the same quantization bins, in which selected elements correspond to adjustments to be made at spatial locations in the first area.
11. The image processing method of claim 1 in which said generating comprises retaining elements for the sparse pattern of elements at spatial coordinates where signal elements of the variable data signal and signal elements of a synchronization component have consistent signal values or fall within the same quantization bins, in which selected signal elements correspond to adjustments to be made at spatial locations in the first area.
12. A retail product package or product label comprising a design printed thereon, the design comprising a first area and a second area, the first area comprising area that is devoid of image or color variability, the second area comprising text, in which the design comprises a sparse pattern of elements at coordinates within the first area, the sparse pattern of elements conveying a machine-readable variable data signal, the sparse pattern of elements comprising a plurality of binary one and binary zero elements, which correspond to ink elements and no-ink elements of the sparse pattern of elements; the ink elements conveyed with an ink color selected through a perceptual analysis that minimizes a visual difference between the ink color and the first area.
13. The retail product package or product label of claim 12 in which the sparse pattern of elements comprises a transformed signal component to carry the variable data signal, in which the signal component comprises synchronization information.
14. The retail product package or product label of claim 13 in which the signal component is transformed to the sparse pattern of elements by removing signal elements of the signal component at coordinates where the signal component does not coincide with coordinates of the variable data signal.
15. The retail product package or product label of claim 13 wherein the signal component is repeated in two-dimensional blocks within the first area, and different sparse patterns are used to distribute the signal component in plural of two-dimensional blocks.
16. The retail product package or product label of claim 12 in which the ink elements comprises varied signal amounts at the ink elements.
17. The retail product package or product label of claim 12 further comprising a predetermined dot shape for the sparse pattern of elements.
18. The retail product package or product label of claim 12 further comprising a predetermined signal amplitude at a dot for the sparse pattern of elements.
19. The retail product package or product label of claim 12 further comprising a predetermined bump shape at a location associated with a region of elements within the sparse pattern of elements.
20. The retail product package or product label of claim 12 in which the first area comprises a blank area.
21. The retail product package or product label of claim 12 in which the first area comprises a uniform color tone.
22. The retail product package or product label of claim 12 in which the sparse pattern elements are selected at spatial coordinates where signal elements of the variable data signal and signal elements of a synchronization component have consistent signal values or fall within the same quantization bins, in which selected elements correspond to adjustments to be made at spatial locations in the first area.
23. The retail product package or product label of claim 12 in which the sparse pattern elements are retained at spatial coordinates where signal elements of the variable data signal and signal elements of a synchronization component have consistent signal values or fall within the same quantization bins, in which selected elements correspond to adjustments to be made at spatial locations in the first area.
24. A non-transitory computer readable medium comprising instructions stored thereon that, when executed by one or more multi-core processors, cause the one or more multi-core processors to perform the following:
obtaining a design file for a retail product package or for a product label, the design file comprising a first area and a second area, the first area comprising area that is devoid of image or color variability, the second area comprising text;
generating a sparse pattern of elements at spatial coordinates within the first area, the sparse pattern of elements conveying a machine-readable variable data signal, the sparse pattern of elements comprising a plurality of binary one and binary zero elements, which correspond to ink elements and no-ink elements of the sparse pattern of elements;
selecting an ink color to use for the ink elements through a perceptual analysis that minimizes a visual difference between the ink color and the first area, in which said selecting yields a selected ink color; and
providing the sparse pattern of elements and the selected ink color to update the design file.
25. The non-transitory computer readable medium of claim 24 in which said generating comprises transforming a signal component to carry the variable data signal, in which the signal component comprises synchronization information.
26. The non-transitory computer readable medium of claim 25 in which the signal component is converted to the sparse pattern of elements by removing signal elements of the signal component at spatial coordinates where the signal component does not coincide with spatial coordinates of the variable data signal.
27. The non-transitory computer readable medium of claim 24 in which said generating comprises selecting elements for the sparse pattern of elements at spatial coordinates where signal elements of the variable data signal and signal elements of a synchronization component have consistent signal values or fall within the same quantization bins, in which selected elements correspond to adjustments to be made at spatial locations in the first area.
28. The non-transitory computer readable medium of claim 24 in which said generating comprises retaining elements for the sparse pattern of elements at spatial coordinates where signal elements of the variable data signal and signal elements of a synchronization component have consistent signal values or fall within the same quantization bins, in which selected signal elements correspond to adjustments to be made at spatial locations in the first area.