An image coding method for a domain corresponding to at least one portion of an image. A minimal triangular partition covering the domain is defined. A square matrix is associated with each of the source triangles by a first reversible transformation so that each matrix represents a specific source triangle. A second reversible decorrelation transformation is applied to each square matrix, resulting in transformed matrixes. The method may be used in isolation, or as a supplement to another coding of the hierarchic type. A corresponding decoding method is also provided.