Secure and efficient steganography methods toembed secret data into cover image without producing distortions in the stegoimage has been proposed. The proposed Zigzag ModST utilizes the neighborhood pixelsinformation to estimate the amount of data that can be embedded into an LSBbits in cover image pixels.  The edgearea pixels are embedded with more number of secret data bits than those in thenon edge areas.

Further, the method improves the stego image quality and theembedding capacity of the secret data. The simulated results of proposed methodprovides an efficient way for embedding secret data into cover images withoutmaking noticeable distortions. It can achieve PSNR of 42 dB and can embed on anaverage of 6 bits per pixel. As part of this work, the secret information is firstencrypted by using standard encryption algorithm and then embedded. In this wayan additional layer of security can be provided to the proposed system.  In Module two, Modulo Substitution Method using Random Technique isimplemented.

This work focused on improving embedding capacity and security. Forobtaining high capacity and high security cover images are separated by R, Gand B components. A random selection of pixels on RGB planes by using pseudorandom index generator is used.  Theproposed method is simulated with different size of secret bits on differentcover images. The simulated results of stego images does not show any changewhen compared to original cover images. The Histogram analysis, Chi squaresteganalysis and RS steganalysis are performed on the stego images proved thatthe proposed methods can effectively resist against attacks. However, Chisquare steganalysis and RS steganalysis shows a limitation on embedding capacityand security.

The proposed modulo based image steganography method was goodupto 33 % of embedding data into the cover images. Thus, the proposed modulobased image steganography method provides limited security and limited embeddingcapacity of the cover image. In Modulethree, pixelvalue modification method usingrandom technique fordata hiding by using pixel value modification with modulus function in colorimages was implemented. This method also guarantees that no pixel value willexceed the range 0 to 255 in stego image. In the existing PVD embeddingmethods, only one secret digit was embedded for two consecutive pixels, but theproposed method, embeds one secret digit in only one pixel.

Proposed method oncolor images gives more capacity and security than the PVD methods. It alsoprovides better visual quality of stego image. Moreover, proposed methodextracts the hidden secret message efficiently without using the range tables. Finally in Module four, zigzag octal pixel value differencing method isproposed using hybrid approach inLSB steganography.The main contributions of this work is in proposing a new PVD method fornon-uniform image segmentation to conceal secret data randomly instead ofsequentially and to use new reference range table instead of Wu and Tsai’srange table.

In the new reference range table has an important advantage thatthe first sub range in the range table needs no modification for embedding of secretdata. Therefore, this proposed method has not disturbed the basic concept ofPVD and HVS (Human Visual System). The proposed method obtains better image qualityand enhanced embedding capacity. The experimented results of histogram analysisand PSNR shows the proposed method provides better results. Proposed methodalso offers better performance over other existing PVD works in terms ofpayload and image quality.