Enhanced Steganographic Scheme Based on Difference Expansion in Digital Images

The advancement of technology in transmitting information over public networks has underscored the importance of data security to protect information. Various research studies have introduced numerous data protection approaches, such as steganography, to enhance the security of confidential information transmitted over public networks. Steganography in digital images, which was a focal point for sensitive data protectors using digital media, has not been sufficiently effective in safeguarding sensitive data due to remarkable distortions found in the stego images. To address this shortcoming, this article introduces a new steganographic approach utilizing pixel difference expansion within small blocks of a digital image. The proposed method segments the cover image into blocks of four pixels calculates differences between these pixels, and embeds secret data by modifying pixel values when the differences fall within a specific range. This process is recorded in a secret key table for accurate data extraction. Experimentations performed on grayscale images of size 512 × 512, got from a publicly used steganography dataset, show a Peak Signal-to-Noise Ratio (PSNR) value ranging between 58.451 and 79.298 decibels (dB), which is always superior to the 30 dB, a standard minimum threshold value for quality stego images in all cases.