A steganographic method based upon JPEG and quantization table modification Chin-Chen Chang a, * , Tung-Shou Chen b,1 , Lou-Zo Chung a a Department of Computer Science and Information Engineering, National Chung Cheng University, Chiayi 62107, Taiwan, ROC b Department of Computer Science and Information Management, Providence University, Taichung 433, Taiwan, ROC Received 17 November 1999; received in revised form 23 December 2000; accepted 8 May 2001 Abstract In this paper, a novel steganographic method based on joint photographic expert- group (JPEG) is proposed. The proposed method modifies the quantization table first. Next, the secret message is hidden in the cover-image with its middle-frequency of the quantized DCT coefficients modified. Finally, a JPEG stego-image is generated. JPEG is a standard image and popularly used in Internet. The stego-image will not be suspected if we could apply a JPEG image to data hiding. We compare our method with a JPEG hiding-tool Jpeg–Jsteg. From the experimental results, we obtain that the proposed method has a larger message capacity than Jpeg–Jsteg, and the quality of the stego- images of the proposed method is acceptable. Besides, our method has the same security level as Jpeg–Jsteg. Ó 2002 Elsevier Science Inc. All rights reserved. Keywords: JPEG; Steganography; Data hiding; Jpeg–Jsteg; DCT Information Sciences 141 (2002) 123–138 www.elsevier.com/locate/ins * Corresponding author. Fax: +886-5-2720-859. E-mail addresses: ccc@cs.ccu.edu.tw (C.-C. Chang), ts.chen@taiwan.com (T.-S. Chen), lzc87@cs.ccu.edu.tw (L.-Z. Chung). 1 Tel.: +886-4-6328001x3408; fax: 886-4-6324045. 0020-0255/02/$ - see front matter Ó 2002 Elsevier Science Inc. All rights reserved. PII:S0020-0255(01)00194-3