In this paper, we propose a novel general non-negative matrix factorization (general-NMF)-based digital watermarking scheme for copyright protection and integrity authentication of the image content. Specifically, the proposed general-NMF algorithm is able to factorize a matrix C ∈ R + s×t into a basis matrix A ∈ R + m×n and a coefficient matrix B ∈ R + p×q by removing the dimension-matching constraints required by the conventional NMF, where s = m, n = p, and t = q. In particular, s = m · l/n, t = l/p · q, and the variable l is the least common multiple of n and p. Furthermore, the generator factor of the random matrix and n are used as the keys of the proposed digital watermarking scheme. Experimental results show that the proposed digital watermarking scheme can effectively resist various attacks and tampering.