The fixing quality of printed images has conventionally been characterized by the adhesion strength between the image and the substrate, and by the cohesion strength within the image layer. In general, techniques such as the simple Scotch tape test and the crockmeter test have been used to evaluate adhesion and cohesion strength respectively. These two test methods are convenient and easy but they can be unreliable due to large variations in the force applied during the tests; the areas selected for optical density measurements can also influence the results.The pen-offset method has also been used to assess fixing quality. In this technique, a print is placed face down on a piece of blank paper, and a pen used to write on the back of the image. The fixing quality is judged by visually inspecting the offset image on the blank paper. The test result depends strongly on the force applied and on the evaluator's experience.The authors have recognized the benefits of the pen-offset method and have developed an apparatus which can apply a constant pressure while writing on the back of the image. An image-processing module has also been developed and compiled into open source code software to evaluate the pen-offset image. The method produces quantitative, reliable and reproducible results.This paper will introduce the new pen-offset apparatus and the methodology for image analysis using a newly developed image processing software.