Ejection amount upper limit value determination method and printing device

A printing device comprising:

• a print head configured to eject liquid onto the medium;
• a control section configured to perform control to form a test pattern including a plurality of patches having different ejection amounts per unit area with respect to the liquid on the medium and configured to perform a process of determining an upper limit value of the ejection amount;
• and
• a reading section configured to read at least a part of the plurality of patches, wherein
• the control section performs
• a first process for acquiring an ejection amount reference value, which is a reference of an allowable range of the upper limit value, and, based on the ejection amount reference value, determining an ejection amount minimum value, which is a minimum value of the allowable range and an ejection amount maximum value, which is a maximum value of the allowable range,
• a second process for obtaining a reading result of at least a part of the plurality of patches from the reading section and, based on the reading result, determining a provisional ejection amount upper limit value, which is a provisional value of the upper limit value, and
• a third process for determining the upper limit value so as to be equal to or larger than the ejection amount minimum value and equal to or smaller than the ejection amount maximum value based on the ejection amount minimum value, the ejection amount maximum value, and the provisional ejection amount upper limit value.