Impact of Steganography on JPEG File Size

Hiding data in JPEG images is usually performed by modifying quantized DCT coefficients. This will affect the entropy coding and consequently the size of the resulting compressed data. The change in the file size might be used as a feature in steganalysis. In this paper, we investigate the impact of several well-known steganography methods on the size of JPEG file. The experiments show interesting results, where we considered several embedding payloads and quality factors. OutGuess 0.1, OutGuess 0.2, and complementary embedding methods increase the file size, while F5, nsF5, and PQ decrease it. The secure steganography methods J-UNIWARD and SI-UNIWARD almost do not change the file size.