Classifying device, classifying program, and method of operating classifying device

摘要

When each pixel forming image data is classified into one of N labels (where N>2) which are ordered from 0 to N−1, a binary graph setting unit sets a binary graph where the i-th layer i is a boundary between the label i−1 and the label i of the N labels, a class to which a label equal to or higher than i is assigned corresponds to a virtual label 0, and a class to which a label equal to or smaller than i−1 is assigned corresponds to a virtual label 1, a layer-by-layer labeling unit performs a graph cut operation on the binary graph of each layer, and then a label determining unit determines which of the N labels each pixel belongs to based on the virtual labels assigned to all the binary graphs.

主权项

1. A classifying device for classifying each pixel forming image data into one of N labels, where N>2, which are ordered from 0 to N−1, the classifying device comprising:
a processor configured to assign each pixel with one of the N labels (i) by using a graph that includes k layers, where k=N−1, which are set between a vertex s and a vertex t and each of which layers is a boundary between the labels, vertices wαv, where α=1, . . . , k, which are set on each layer α, where α=1, . . . , k, and which vertices correspond to locations v of individual pixels of the image, and edges each connecting two of the vertices wαv, the vertex t, and the vertex s, and (ii) by determining edges to be cut among the edges by a graph cut operation, wherein the processor is configured to execute the following instructions, which comprise: setting, for each i-th layer i that is the boundary between a label i−1 and a label i of the N labels, a binary graph including edges each connecting two of the vertices wiv, the vertex s corresponding to a virtual label 0, and the vertex t corresponding to a virtual label 1, wherein the virtual label 1 indicates that a label that is equal to or higher than i is assigned to the location v corresponding to the vertex wiv on the layer i, and the virtual label 0 indicates that a label that is equal to or lower than i−1 is assigned to the location v corresponding to the vertex wiv on the layer i; setting an energy for each edge of the binary graph for each layer depending on which of the virtual label 0 and the virtual label 1 each vertex belongs to; assigning one of the virtual label 0 and the virtual label 1 to each vertex wiv on each layer by determining edges to be cut among the edges of the binary graph of the layer by performing a graph cut operation on the entire graph including the binary graphs for the individual layers with the energies set therefor, and determining which of the N labels the pixel at each location v belongs to depending on which of the virtual label 0 and the virtual label 1 is assigned to each vertex wiv, where i=1, . . . , k, on the first to the k-th layers, which corresponds to the same location v, wherein the binary graph includes an edge that connects two vertices wiv on the same layer i to each other, an edge (s,wiv) that connects the vertex s to each vertex wiv, and an edge (wiv,t) that connects each vertex wiv to the vertex t, wherein the processor determines, for each vertex wiv, that the label 0 is assigned to the pixel corresponding to the vertex wiv if all the vertices wiv corresponding to the same location v on all the layers belong to the virtual label 0, that the label N−1 is assigned to the pixel corresponding to the vertex wiv if all the vertices wiv corresponding to the same location v on all the layers i belong to the virtual label 1, and that the pixel corresponding to the vertex wiv belongs to a class p if the vertices wiv corresponding to the same location v on the first to the p-th layers belong to the virtual label 0 and the vertices wiv corresponding to the same location v on the p+1-th to the N−1-th layers belong to the virtual label 1, and wherein the processor sets a fourth- or higher order energy, which is determined depending on whether or not all of arbitrary four or more vertices on the same layer belong to the virtual label 0 or the virtual label 1, for each of edges that connect the four vertices wiv to the vertex s or the vertex t via a virtual vertex vi for each layer.