The Digital Image Correlation (DIC) was used to identify crack growth law by using Williams expansion series. The identification process was carried out in three steps: (i) determination of displacement fields on each considered load cycle, (ii) determination of the terms of Williams expansion series by minimizing the difference between experimental fields and analytical solutions of Williams [1], and (iii) the coefficients found are used for initialization of the third step, which is an integrated Digitial Image Correlation (iDIC). The procedure enables to get more accurate results than a simple projective method and to decrease the time of identification of the integrated correlation by the initialization with results from the projective method.