Hi Paul,

1. The predefined prior is the proportion of the standard deviation of noise of each random regressor images to the main modality image (or the inverse proportion signal to noise ratio (SNR) of the regressor images to the main modality image). For example, the estimated SNR of the main modality is 20, the estimated SNR of one regressor image is 30, than you can set the predefined prior to be 20/30.

2. The specified window size is used to estimate the standard deviation of noise of each images. The default estimation method is the stdfilt function in MATLAB. Please refer to the MATLAB function for more detail of selecting the window size.

3. Did you set up a predefined prior or set up a window size?

Thanks for your interest. Please let me know if you have further questions.

Xue