How to get Euler angles with respect to initial Euler angle I have a sensor which gives me Euler angles (roll,pitch,yaw). There is a baseline value of Euler angle (assume it is $5,10,15$) at the beginning.I want to calibrate from this baseline values all subsequent value. How can I get those values? Is it just subtract $5,10,15$ from all values Or is there any rotational matrix for doing so? As an example if any time the value is $5,10,15$ then it should show $0,0,0$ and on the same way show other angle values with respect to the baseline values.I don't know how to do this.
Please advise.

First, you cannot add or subtract Euler angles.  They are not vectors.  You need to convert the Euler angles to a representation that can be composed such as a rotation matrix or unit quaternion.  If $R_b$ is the base line rotation matrix and $R_i$ is a given rotation matrix, then you can measure rotation w.r.t. the baseline using the following formula $R = R_b^{T}R_i$.
To convert from Roll, Pitch, Yaw angles, you need to compose three rotation matrices about the Z, Y and X axes (assuming that Z ~ yaw, Y ~ pitch, and X ~ roll in the local frame).  This is just a composition of the three coordinate rotation matrices:
$$R = R_z R_y R_x.$$
To get the euler angles back I refer you to the following: https://stackoverflow.com/questions/11514063/extract-yaw-pitch-and-roll-from-a-rotationmatrix
