Perceptual similarity image retrieval

A method of generating a plurality of spots associated with an image, a spot comprising a connected region of the image and having substantially similar visual characteristics, the method comprising:

• the steps of
• receiving an array of pixel representations;
• partitioning the array of pixel representations to generate an array of cells, the array have first and second axial directions, each cell comprising a like-sized connected region of the image;
• determining a plurality of visual characteristics of each cell;
• joining cells connected along the first axial direction to form a plurality of disjoint intervals, each interval having visual characteristics that vary by at most a first tolerance;
• and
• joining intervals connected along the second axial direction to form at least one spot, each spot having visual characteristics that vary by at most a second tolerance.

A method of generating a description of the shape of a region in a digital image, the method comprising the steps of:

• generating an approximation of the shape of the region, said approximation comprising a plurality of connected like-sized cells that intersect the region;
• generating a sequence of coordinates along a boundary curve of the approximation;
• transforming the sequence of coordinates to a spectral domain;
• and
• processing a plurality of lower frequency spectral coefficients of the transformed sequence to generate the description of the region.

A computer readable medium carrying instructions executable by a computer to perform a method of indexing images according to visual characteristics of the images, the method comprising the steps of:

• receiving an array of pixel representations that represent an image;
• processing the array of pixel representations to determine a plurality of spots associated with the image, each spot comprising a connected region of the image having selected visual characteristics that vary spatially within a selected tolerance;
• generating a plurality of spot descriptors, each spot descriptor indicating the visual characteristics of a respective spot;
• and
• using the plurality of spot descriptors as an index entry for the image.

A computer readable medium carrying instructions executable by a computer to perform a method of generating a plurality of spots associated with an image, each spot comprising a connected region of the image having substantially uniform visual characteristics, the method comprising the steps of:

• receiving an array of pixel representations;
• partitioning the array of pixel representations to generate an array of cells, the array having first and second axial directions, each cell comprising a like-sized connected region of the image;
• determining a plurality of visual characteristics of each cell;
• joining cells connected along the first axial direction to form a plurality of disjoint intervals, each interval having visual characteristics that vary spatially by at most a first tolerance;
• and
• joining intervals connected along the second axial direction to form at least one spot, each spot having visual characteristics that vary spatially by at most a second tolerance.

A computer readable medium carrying instructions executable by a computer to perform a method of generating a description of a shape of a region in a digital image, the method comprising the steps of:

• generating an approximation of the shape of the region, said approximation comprising a plurality of connected like-sized cells that intersect the region;
• generating a sequence of coordinates along a boundary curve of the approximation;
• transforming the sequence of coordinates to a spectral domain;
• and
• processing a plurality of lower frequency spectral coefficients of the transformed sequence to generate the description of the region.