Unsigned magnetograms reconstructed from the Ca II K images taken on 01 April 2011 (top) and 07 June 2010 (bottom) using the average parameters for PFL^* (left), SDO/HMI unsigned magnetograms (middle) co-temporal to the Ca II K images, and difference between the reconstructed unsigned magnetogram (simulated) from Ca II K data and the original (true) SDO/HMI unsigned magnetogram (right). The rms, mean, mean absolute, and maximum absolute differences are listed under each panel. The colour bars show the ranges of |B_LOS| in G. All images are saturated at 100 G to improve the visibility of the regions with low magnetic field strength.