Any orthogonal transformation of the digital grayscale image can be represented by a set of images to be an orthonormal basis. For such representation digital data scattering was considered that is important in applications, particularly for the robust watermarking techniques. We introduce a block matrix, elements of which are basis images. This matrix is found to be useful for representation of multi-dimensional arrays, that can describe a set of digital images. This representation has new features concerning the data scattering. A steganographic scheme for frequency domain watermarking based on this representation is considered.