Abstract: A new secure image transmission technique which changes naturally a given enormous volume secret image into a secret-fragment-visible image is called mosaic image of the exactly similar size. The mosaic image, which looks to be like an discretionarily choose target image and it may be used as a disguise of the secret image, is yielded by separating the secret image in sections and changing their shading attributes to those of the comparing pieces of the target image. Skillful techniques are invented to lead the shading change process so that recovered secret image may be almost losslessly. A scheme for handling overflows/underflows in the converted pixels shading values by recording the shading contrast in the untransformed shading space is proposed in addition. The data needed for improving the secret image is embedded in the created mosaic image by a lossless information concealing plan using a key.

Keywords: mosaic image,image encryption, data hiding , secure image transmission.