This notebook is a toy example which perform a cover source switching from ISO100 to ISO200 using the rights *(a, b)* for the database. The sampling can be done using different methods : MVG, Cholesky and Rejection-Sampling.
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``` python
cwd=os.getcwd()
cover_path=cwd+'/ISO100/EYED5607.DNG'
cover_name=os.path.basename(cover_path)
```
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## 1 Sampling of undecimated DCT coefficients
Available sampling strategies :
* Using MVG/Cholesky over 4 lattices
* Using MVG/Cholesky to preserve intra correlations only
* Using MVG/Cholesky to sample under independance hypothesis of DCT coefficients
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### 1.1.a Using MVG/Cholesky over 4 lattices
The two lines were used to obtain the result of the **Table I** and row **'J-Cov-NS'**.
### 1.1.c Using MVG/Cholesky to sample under independance hypothesis of DCT coefficients
Used to confirm the results obtained by Tomáš Denemark, Patrick Bas, and Jessica Fridrich in the paper called *'Natural Steganography in JPEG Compressed Images'* published in *'Electronic Imaging 2018'* and shown in the article at **Table I** and row **'Independent embedding'**.