Automatic geometric image transformations using embedded signals

A method for operating a processor-controlled machine to decode periodic signals embedded in an image;

• the machine including a processor and a memory device for storing data;
• the data stored in the memory device including instruction data the processor executes to operate the machine;
• the processor being connected to the memory device for accessing and executing the instruction data stored therein;
• the method comprising:
• operating the processor to obtain an image data structure defining an image;
• the image including a set of n periodic signals embedded therein;
• the set of n periodic signals having geometric relationships with respect to each other;
• operating the processor to obtain geometric constraint data indicating expected geometric relationships about the set of n periodic signals embedded in the image;
• operating the processor to identify a plurality of local peak power concentrations in a two-dimensional spatial frequency power spectrum of the image;
• operating the processor to eliminate a subset of the local peak power concentrations that do not satisfy the geometric constraint data indicating expected geometric relationships about the set of n periodic signals embedded in the image;
• a remaining subset of the local peak power concentrations being determined to be candidate local peak power concentrations indicating spatial frequencies and directions of the set of n periodic signals;
• and
• operating the processor to compute a best linear mapping between sets of n candidate local peak power concentrations in the image and a set of n periodic signals indicated by the geometric constraint data;
• the best linear mapping identifying the spatial frequencies and directions of the set of n periodic signals embedded in the image.

An article of manufacture for use in a machine that includes a memory device for storing data;

• a storage medium access device for accessing a medium that stores data;
• and a processor connected for accessing the data stored in the memory device and for receiving data from the storage medium access device;
• the article comprising:
• a data storage medium that can be accessed by the storage medium access device when the article is used in the machine;
• and
• data stored in the data storage medium so that the storage medium access device can provide the stored data to the processor when the article is used in the machine;
• the stored data comprising instruction data indicating instructions the processor can execute;
• the processor, in executing the instructions, obtaining from a signal source an acquired image data structure defining an acquired image;
• the acquired image being a version of an original image and additionally having embedded signals therein not included in the original image;
• the embedded signals having geometric relationships with respect to each other;
• the processor, further in executing the instructions, obtaining geometric constraint data indicating expected geometric relationships about the embedded signals in the acquired image;
• the processor, further in executing the instructions, determining the geometric relationships of the embedded signals in the acquired image;
• the processor, further in executing the instructions, computing geometric differences between the acquired image and the original image using the geometric relationships of the embedded signals in the acquired image and using the geometric constraint data indicating the expected geometric relationships of the embedded signals in the original image;
• the processor, still further in executing the instructions, transforming geometric properties of an acquired image version of an original image to match geometric properties of the original image using the geometric differences computed between the acquired and original images.