Distribution function of the stellar photometry data from the B-band image including Berkeley 75. The black dots are the locations of stars without considering their brightnesses, the red dot is the center of Berkeley 75 and the red circle indicates the radius ﹩1\buildrel{\,\prime}\over{.} 9﹩ of Berkeley 75. The white-magenta dot symbols are the members of Berkeley 75. The left color bar shows the values of the normalized number density function and the right color bar the membership probability for each star.