Examples of Carrington maps constructed from Ca II K data over rotations 1664 (17 January–12 February 1978, left) and 1667 (9 April–5 May 1978, right). Shown are Kodaikanal data processed by Chatzistergos et al. (2020c, 1st row) and by Chatterjee et al. (2016, 2nd row) as well as Mt Wilson data processed by Bertello et al. (2020, 3rd row) and Chatzistergos et al. (2020c, 4th row). Due to differences in the image processing the images are saturated at different levels in order to show plage at roughly similar levels. In particular, the contrast ranges are [−0.5, 0.5] for the images processed by Chatzistergos et al. (2020c, 1st and 4th rows) and [−1, 1] for the images processed by Bertello et al. (2020, 3rd row), while the ones processed by Chatterjee et al. (2016, 2nd row) are shown to their entire range since they are provided in PNG file format and the exact contrast values are not known to us. White areas are caused by gaps in the data.