Image compression by texture modeling in the wavelet domain.

High-quality image compression algorithms are capable of achieving transmission or storage rates of 0.3 to 0.5 b/pixel with low degradation in image quality. In order to obtain even lower bit rates, we relax the usual RMS error definition of image quality and allow certain "less critical" portions of the image to be transmitted as texture models. These regions are then reconstructed at the receiver with statistical fidelity in the mid- to high-range spatial frequencies and absolute fidelity in the lowpass frequency range. This hybrid spectral texture modeling technique takes place in the discrete wavelet transform domain. In this way, we obtain natural spectral texture models and avoid the boundary blending problems usually associated with polygonal modeling. This paper describes the complete hybrid compression system with emphasis on the texture modeling issues.

Comparison of the results of a standardized AIDS prevention program in three geographic locations.

A standardized AIDS prevention program, Stop AIDS, was tested with gay and bisexual men in 3 different geographic locations: metropolitan Chicago; Orange County, California; and Phoenix, Arizona, employing a test of AIDS knowledge, attitudes, and behavior. Results indicted that the Chicago participants began with the most knowledge about AIDS but gained least in the workshop, ending lowest, while the Orange County participants started with the least knowledge and gained the most, ending highest. The same change pattern was demonstrated in terms of attitudes. However, all groups started the discussion group with approximately the same risk behavior for HIV transmission, and all groups committed to the same amount of change in risk behavior at workshop termination, demonstrating the independence of behavior change from knowledge and attitude changes. Additionally, all 3 groups had the same 8 of 15 significant correlations of measures with no correlation between knowledge about AIDS, attitudes toward AIDS, and post-workshop intentions regarding risk behavior. These results indicate that Stop AIDS is an effective prevention program in all 3 locations, but that this and other programs should emphasize actual risk-behavior change rather than knowledge increase or healthier attitudes to produce the greatest lethality reduction.