Using a Novel Variable Block Size Image Compression Algorithm for Hiding Secret Data

This paper presents a data hiding scheme that hides the data in the compression domain of a digital image. A quadtree decomposition algorithm decomposes the host image into blocks of variable sizes according to histogram analysis of the block residuals. Variable block sizes are then encoded at different rates based on their visual activity levels. The majority of secrete data are embedded into the smooth area of the image, while a small portion of the secret data are hidden in the compression codes of the high detailed blocks. Experimental results confirm that the proposed scheme can embed a large amount of data in the compressed file while maintaining satisfactory image quality

A new predictive image compression scheme using histogram analysis and pattern matching

In this paper, we introduce a new predictive image compression scheme that compresses an image by a set of parameters computed for individual blocks of different types. These parameters include the average and difference of the representative intensities of an image block, together with the index of a pattern associated with the block visual activity. The block representative gray values are computed through a histogram analysis of the block residuals and a pattern matching technique is employed to find the best match for the block bit-pattern from a pre-defined pattern book. To further reduce the bit rate, a predictive technique selectively predicts the parameters based on the corresponding values in the neighboring blocks. The simulation results confirm that the proposed technique can provide a high compression ratio with acceptable image quality of the compressed images

A new quad-tree segmented image compression scheme using histogram analysis and pattern matching

In this paper, a new variable block-size image compression scheme is presented. A quadtree segmentation is employed to generate blocks of variable size according to their visual activity. Inactive blocks are coded by the block mean, while active blocks are coded by the proposed matching algorithm using a set of parameters associated with the pattern appearing inside the block. Both the segmentation and the pattern matching are carried out through histogram analysis of block residuals. The use of pattern parameters at the receiver together with the quadtree code reduces the cost of reconstruction significantly and exploits the efficiency of the proposed technique

Race, gender & class : an interdisciplinary and multicultural journal

In this paper, a digital watermarking technique for copyright protection or ownership identification of digital media is introduced. In the proposed scheme, a novel classifier is employed to measure the visual activity of the image blocks. The proposed approach utilizes the level of visual activity within the host image and modifies the intensities of some pixels in image blocks accordingly. The described technique, is an invisible, image watermarking technique in the spatial domain and the experimental results show that the watermark can be extracted properly under image processing and destroying operations