A Modified LSB Technique of Digital Watermarking in Spatial Domain

Digital watermarking is a technique of embedding pieces of information into digital data such as text, audio, video, and still images that can be detected or extracted later to show authentication about the data. Watermark is hidden information in the image(s) and is so designed that it does not degrade/distort the quality of the image and still keeps the information. Digital watermarking is basically to protect ownership rights and to control of making illicit copies of digital data. In this paper, we have discussed various watermarking techniques and properties and have proposed a modified LSB technique. We have implemented the proposed technique by following: 2-bits of 8-bit gray image is replaced by luminance part, next 2-bits by red component, next 2-bits by green component and next 2-bits by blue component of 32-bit image using secret key. The advantage is that watermarking capacity has been increased and unaffected by various attacks e.g. zero out LSB bits, cropping etc. Watermark image is imperceptible in resultant image. We have tested this technique on several images and found that it is quite satisfactory. This technique is secured as unauthorized user can not extract the watermarked contents easily from the original image and works well in adverse situations. We have implemented this technique on platform java 1.5.0.