Humidity fastness is an important attribute for inkjet printing materials. The test methods of humidity induced color change and loss of line quality are presently discussed in the ISO/TC42/WG5, where a method using checkerboard pattern as the test target is proposed for the quantitative estimation. In this study, we assessed the effectiveness of the method investigating the correspondence between the checkerboard measurement to the psychophysical evaluation, where we carried out extensive tests with a wide range of commercially available inkjet inks and media. At the same time, we reviewed test conditions, such as temperature, humidity and duration, in order to determine the appropriate standard test method as the ISO.