Effect of saturated pixels on security of steganographic schemes for digital images

When hiding messages in digital images, care needs to be exercised how the embedding changes are executed in or near saturated pixels. In this paper, we consider three different rules that are currently being used that adjust the embedding in saturated pixels and assess their impact on empirical steganographic security of four modern embedding algorithms. Surprisingly, the rules can have a major effect, especially in image sources with stronger noise. We show that the preferred way to treat saturated patches during message hiding is to adjust the pixel costs to entirely avoid making embedding changes in saturated pixels despite the ensuing loss of embedding capacity. This paper hopes to raise the awareness of the importance of treatment of saturated pixels in steganography to avoid introducing easily correctable flaws that may negatively affect security.