Quad-tree Decomposition Based Image Analysis Using Intensity Difference Threshold

The watermark bit assignment controls the watermark embedding strength and the bit plane selection. Quad-tree decomposition is used as analysis technique which involves subdividing of image into blocks that are more homogeneous in comparison to the image itself. This technique gives the information about the structure of the image. This is the first step in adaptive compression algorithms. For the gray scale images, intensity difference threshold Vint is used for the verification whether further quad-tree decomposition is required or not. This paper defines an intensity threshold is used as Tint. If the value of Tint is less than the value of Vint, the image decomposition will take place into four sub blocks until, the value of Tint becomes greater than Vint, finally the size of sub block reaches to its minimum value. How much details is inside the image is determined by the complexity of the image. If the complexity value is high, the corresponding image is more complex and contains more detailed information. The quality of more complex images degrades faster than less complex images under the same distortion. This paper reveals the quad tree decomposition under different threshold values.