We propose an algorithm to embed data directly in the bitstream of JPEG imagery. The motivation for this approach is that images are seldom available in uncompressed form. Algorithms that operate in spatial domain, or even in coefficient domain, require full (or at best) partial decompression. Our approach exploits the fact that only a fraction of JPEG code space is actually used by available encoders. Data embedding is performed by mapping a used variable length code (VLC) to an unused VLC. However, standard viewers unaware of the change will not properly display the image. We address this problem by a novel error concealment technique. Concealment works by remapping run/size values of marked VLCs so that standard viewers do not lose synchronization and displays the image with minimum loss of quality. It is possible for the embedded image to be visually identical to the original even though the two files are bitwise different. The algorithm is fast and transparent and embedding is reversible and file-size preserving. Under certain circumstances, file size may actually decrease despite carrying a payload.

In this letter, we propose a fragile digital watermarking algorithm that is directly applicable to compressed bit streams and is mathematically lossless with practically no increase in file size. The algorithm exploits the inefficiency of the code space of popular compression standards by recognizing that not all code words appear in the bit stream. By mapping the code words to the outside of the used code space, we can embed the watermark into the stream as forced bit errors. The decoder recognizes such code words, recovers the watermark from them, and restores the media to its original state. As proof of the concept, the algorithm is then applied to the JPEG bit stream.Index Terms-Compressed domain watermarking, file size preservation, lossless watermarking.

In a previous work we proposed an algorithm to embed watermark bits directly in a compressed bitstream. The embedding algorithm is reversible, requires no decompression, causes no increase in file size, and is fast. The problem is that the watermarked bitstream will either lose format-compliance or suffer unacceptable visual degradation. We have now solved these problems for JPEG streams. The algorithm determines the AC VLC codespace that is actually used by the image. Watermarking specific VLCs places the resulting codewords outside of the used codespace, but still within the original VLC table specified in JPEG standard. To keep the watermarked stream format-compliant and visually acceptable, the run/size values of watermarked VLCs are remapped in a way to keep visual degradation to a minimum. Since watermarked VLCs are never used in the image, this remapping does not alter the image outside of watermarked VLC codespace. Security, Steganography, and Watermarking of Multimedia Contents VII, edited by Edward J. Delp III, Ping Wah Wong, Proc. of SPIE-IS&T Electronic Imaging, SPIE Vol. 5681 © 2005 SPIE and IS&T · 0277-786X/05/$15 539 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/28/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

A longitudinal study of the impact of three separate volunteer programs working with juvenile delinquents was undertaken at one juvenile court. The youth were followed for a period of one year with measures of official and unofficial delinquent behavior obtained four times during that year. Other data were also collected. The study results indicated two of the programs (i.e., volunteer probation officer and group counseling) had a negligible effect on reducing probationers' delinquent behavior compared to a control group. Youth who participated in the third group, a volunteer tutor program, actually increased their delinquent behavior when compared to a control group within the first 6 months of their probation. However, one year after probation, the differences were negligible. Recommendations are made which include divesting the juvenile court of client responsibility for providing volunteer services.

Recovery-oriented interventions will be most effective for older individuals when service providers take into account their personal histories and the propensity of many older adults to associate recovery with symptom improvement even while embracing other life improvements.