| Summary: | 碩士 === 國立成功大學 === 電腦與通信工程研究所 === 93 === Abstract
To date the most commonly used technique is the DCT-based JPEG. However, JPEG compressed images at low bit rates will result in block effects. The next generation for image compression standard is the wavelet-based JPEG2000. JPEG2000 also provides for new functionality like the ROI (Region of Interest). In this paper, we propose the ROI watermarking embedded scheme in JPEG200.
There are three positions in JPEG200 coding flow for information hiding. The first is after the images transform the image data are transformed to wavelet coefficients. For the digital watermarking, the payload is usually low, and multiple embedding with the majority detection or the spread-spectrum concept can be applied. The second hiding location is after quantization .And last hiding location is embedded in the output of tier-2 coding, it can be guaranteed that all the embedded information will be received without error and in a correct order because we avoid the two major sources of information loss.
In this paper, we proposed a hybrid watermarking scheme to embed and extract based on the JPEG2000 Codec. Our scheme mix spatial domain watermarking (W1 embedded in gray-level coefficients before JPEG2000 compression) and frequency domain watermarking (W2 embedded in ROI coefficients after quantization). Distortion reduction technique was used on image to lessen image degradation caused by embedding. This kind of scheme is robust to attacks like cut-and-paste, mean filter, luminance, and more.
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