The initial magnetization curve of ac demagnetized CoNi thin films were outside the hyteresis loop boundary before saturation. Using -dc demagnetization, the initial magnetization curve was brought into the hysteresis loop boundary. Henkel plot shows negative deviation in ac demagnetized CoNi thin film, and both positive and negative deviation, in -dc demagnetized CoNi film. Bitter domain imaging technique showed that the initial magnetization effects are due to the corresponding domain configurations obtained in ac and in -dc demagnetization. (C) 2004 American Institute of Physics.