Graphical Element Edge Marking for Robust Mobile Detection

The graphical element is divided into multiple coherent edge portions that are selected and processed independently. Each edge portion can be shifted along its own family of curves, allowing localized adaptation to deformations without affecting the entire graphical element. This segmentation enables the marking to maintain robustness even when parts of the graphical element undergo quality reduction or distortion during printing.

The invention changes the geometric parameters of selected edge portions by shifting them along families of curves. This parameter change creates a marking that is encoded in the relative positions of edge portions rather than in the absolute content of the graphical element. Such parameter-based encoding is inherently more robust to printing deformations because it relies on geometric relationships that can be recovered even when the overall quality deteriorates.

The marking is applied locally to specific coherent edge portions rather than uniformly across the entire graphical element. By selecting edge portions that are less critical to the visual identity of the graphical element and applying shifts only to these localized regions, the marking becomes imperceptible to the human eye while still encoding information. The local application ensures that the overall aesthetic and brand impact of the graphical element remains intact.

Instead of modifying the entire graphical element, the invention applies partial action by selecting and modifying only specific coherent edge portions. This partial modification is sufficient to encode the required information while being imperceptible to human observers. The selective approach ensures that the most visually critical parts of the graphical element remain unchanged, preserving brand impact.

The graphical element is segmented into multiple coherent edge portions, each of which is processed independently. By working with individual edge portions rather than the entire graphical element as a global image, the invention preserves the smoothness and continuity of each edge segment. The segmentation allows for precise control over edge modifications, ensuring that smoothness is maintained while information is encoded in the relative positions of the segments.

The invention uses families of smooth curves to define the paths along which edge portions are shifted. These curves maintain the natural curvature and smoothness of the original graphical element edges. By constraining the shifts to follow smooth curve families rather than applying arbitrary global transformations, the invention preserves the aesthetic quality and smoothness of the graphical element edges while still encoding information through the shifted positions.

The marking is encoded in terms of geometric parameters (relative positions of coherent edge portions along curve families) rather than absolute pixel values. This parameter-based encoding allows the detection system to recover the marked information by measuring geometric relationships that are invariant to surface curvature and distortion. The detection process focuses on measuring the shifted positions of edge portions relative to their original locations, which can be accurately determined even when the graphical element is applied on a curved surface or subjected to distortion.

The detection process segments the graphical element into coherent edge portions and processes each segment independently. By detecting the position of each edge portion separately and comparing it to its expected position based on the family of curves, the system can accurately retrieve the marked information even when the overall graphical element is distorted or on a curved surface. The segmentation approach allows for local geometric measurements that are more robust to global deformations than holistic image processing methods.