WEEK 5 FYP 2

Title:

Research for Masking and Filtering

Objective:

To know deeply about Masking and Filtering method used in Image Steganography

Content/Result:

• Masking and filtering techniques are mostly used on 24 bit and greyscale images. They hide info in a way similar to watermarks on actual paper and are sometimes used as digital watermarks. 

• Masking images entails changing the luminance of the masked area. The smaller the luminance change, the less of a chance it can be detected. Because watermarking techniques are more integrated into the image,they may be applied without fear of image destruction from lossy compression. 

• By covering, or masking a faint but perceptible signal with another to make the first non-perceptible, it exploit the fact that the human visual system cannot detect slight changes in certain temporal domains of the image.

• Masking techniques are more suitable for use in lossy JPEG images than LSB insertion because of their relative immunity to image operations such as compression cropping. Stego-images that are masked will keep a higher fidelity than LSB through compression, cropping and some image processing. The reason that a stego image encoded with masking, degrades less under JPEG compression is that the secret message is hid in the significant areas of the picture.

The left image is the original image. The right image is image after masking and filtering technique applied

Conclusion:

Masking does change the visible properties of an image, it can be done in such a way that the human eye will not notice the anomalies. It is more robust than LSB modification with respect to compression, cropping and different kinds of image processing. The information is hidden inside the visible part of the image, which makes it more suitable than LSB modifications in case a lossy compression algorithm like JPEG is being used.