An improved least-significant-bit substitution method using the modulo three strategy

• We proposed a novel method to embed a series of ternary secret data based on LSB.
• The proposed scheme can hide two ternary numbers into each grayscale pixel, normally only modify the two LSBs of the pixel.
• Our proposed scheme has higher resistance ability and achieves a higher PSNR.

In this paper, we proposed a novel method to embed a series of ternary secret data into a cover image based on an improved Least-Significant-Bit (LSB) scheme using the modulo three strategy. Our new method can hide two ternary numbers into each grayscale pixel, normally only modify the two LSBs of the pixel, while it may cause overflow/underflow and a carry/borrow. We solve these problems by adding 1 to the pixel or subtracting 1 from the pixel before embedding. The embedding capacity of our method can be 3.1699 bpp. At the same time, the quality of the stego image of our new method also is better than traditional LSB scheme when the embedding capacity is greater than 3 bpp with a Peak Signal-to-Noise Ratio (PSNR) greater than 37 dB. Extensive experimental results indicated that our new method is capable of getting a higher PSNR than traditional LSB scheme when the embedding capacity is greater than 3 bpp, and it has higher resistance ability against the chosen steganalysis algorithm when the embedding capacity is low.