For the higher coding performance than the previous video coding standards, high
efficiency video coding (HEVC) adopts an angular intra prediction method, which
requires heavy computational complexity due to the increased intra prediction
modes. In this paper, we propose a fast intra prediction mode decision based on
the estimation of rate distortion cost using Hadamard transform to reduce the
number of intra prediction mode and early termination whether the current coding
unit is splitted or not. The experimental results show that the proposed method
reduces the computational complexity of intra prediction in HEVC and achieves
similar coding performance to that of HEVC test mode 2.1
The previous steganographic algorithm results in the modification of the image statistic, especially histogram of
the coefficients. We propose a method to compensate for the histogram modification due to embedding. The
new algorithm estimates the modification before the embedding process has started and modifies the histogram
in advance so that the modification due to embedding is less noticeable. We have implemented our methods in
Java and performed the extensive experiments with them. The experimental results have shown that our new
method improves our previous steganographic algorithms by decreasing distortion and histogram modification.
It is well known that all information hiding methods that modify the least significant bits introduce distortions into the cover objects. Those distortions have been utilized by steganalysis algorithms to detect that the objects had been modified. It has been proposed that only coefficients whose modification does not introduce large distortions should be used for embedding. In this paper we propose an effcient algorithm for information hiding in the LSBs of JPEG coefficients. Our algorithm uses parity coding to choose the coefficients whose modifications introduce minimal additional distortion. We derive the expected value of the additional distortion as a function of the message length and the probability distribution of the JPEG quantization errors of cover images. Our experiments show close agreement between the theoretical prediction and the actual additional distortion.