This thesis intends to problematize the role of the observing subject when confronted with images, more specifically, when confronted with images of injustice. Bearing in mind that, as everything indicates, we live in a time in which images have never been so much in evidence, have never been so debated, have never gone so much viral and have never reached such high levels of dissemination, we are increasingly facing the ethical demand of how to handle them. First, we investigate the image not as an object – whether it be material or psychic, plastic or narrative, etc. – passive, waiting for an eye to take over them. The image is alive and interacts with a gaze that engages with it. However, in order to reflect critically on the relationship between subject and image, we outline, as one of the specific objectives of this work, the analysis of some levels through which images are addressed, manipulated and governed. In a second moment, we aim to discuss, based on the philosophy of Georges Didi-Huberman, the ability that images have, far beyond the way they are managed, to take a position (to testify, to resist). Next, we postulate that the expanded concept of witness, formulated by Jeanne Marie Gagnebin, can be an alternative for thinking about responses to the question about what to do with the image that is not mine, but that requires me to have a critical attitude.