sklearn.feature_extraction.image.img_to_graph(img, *, mask=None, return_as=<class 'scipy.sparse._coo.coo_matrix'>, dtype=None)[source]

Graph of the pixel-to-pixel gradient connections.

Edges are weighted with the gradient values.

Read more in the User Guide.

imgndarray of shape (height, width) or (height, width, channel)

2D or 3D image.

maskndarray of shape (height, width) or (height, width, channel), dtype=bool, default=None

An optional mask of the image, to consider only part of the pixels.

return_asnp.ndarray or a sparse matrix class, default=sparse.coo_matrix

The class to use to build the returned adjacency matrix.

dtypedtype, default=None

The data of the returned sparse matrix. By default it is the dtype of img.

graphndarray or a sparse matrix class

The computed adjacency matrix.


For scikit-learn versions 0.14.1 and prior, return_as=np.ndarray was handled by returning a dense np.matrix instance. Going forward, np.ndarray returns an np.ndarray, as expected.

For compatibility, user code relying on this method should wrap its calls in np.asarray to avoid type issues.