A New Method of Image Steganography Using Last Three Bit Plane of Gray Scale Images

Objectives: The objective of this technique is to maximize the capacity and imperceptibility of the secret data with minimal modification to the cover image. Methods: In this paper, a new image steganography method is proposed that hides secret data in a selected carrier image. The proposed steganography method primarily extracts the last three bit of the selected pixel and then performs the XOR operation with 3rd, 1st and 3rd, 2nd bit. On the basis of result of XOR operation every bit of secret data is embedded one by one on LSB of the selected pixel value. Findings: This method comes under +1 or -1 change in pixel value of a Stego image. Due to +1 or -1 modification, the method shows minimum degradation in the Stego image. As each pixel can carry data bit, the chance of message hidden is 100%. Experimental results indicate that our method achieves good image quality and fairly large data hiding capacity. For experimental results, four standard images were taken and analyzed on the basis of different parameters such as PSNR, MSE, Mean and Standard Deviation, Number of pixels used and Number of pixels changed etc. The experimental results show that our method gives good imperceptibility as degradation is only +1 and -1 in a pixel. The proposed method was better when compared to LSB and chaotic method. Novelty/Improvement: The chance of message hidden is 100%. The proposed method improves the results to achieve good capacity and imperceptibility.