This paper shows how a machine, which observes stimuli through an uncharacterized, uncalibrated channel and sensor, can glean machine-independent information (i.e., channel-and sensor-independent information) about the stimuli. This is possible if the following two conditions are satisfied by the observed stimulus and by the observing device, respectively: 1) the stimulus' trajectory in the space of all possible configurations has a well-defined local velocity covariance matrix; 2) the observing device's sensor state is invertibly related to the stimulus state. The first condition guarantees that statistical properties of the stimulus time series endow the stimulus configuration space with a differential geometric structure (a metric and parallel transfer procedure), which can then be used to represent relative stimulus configurations in a coordinate-system-independent manner. This requirement is satisfied by a large variety of physical systems, and, in general, it is expected to be satisfied by stimuli with velocity distributions varying smoothly across stimulus state space. The second condition means that the machine defines a specific coordinate system on the stimulus state space, with the nature of that coordinate system depending on the machine's channels and detectors. Thus, machines with different channels and sensors "see" the same stimulus trajectory through state space, but in different machine-specific coordinate systems. It is shown that this requirement is almost certainly satisfied by any device that measures more than 2d independent properties of the stimulus, where d is the number of stimulus degrees of freedom. Taken together, the two conditions guarantee that the observing device can record the stimulus time series in its machine-specific coordinate system and then derive coordinate-system-independent (and, therefore, machine-independent) representations of relative stimulus configurations. The resulting description is an "inner" property of the stimulus time series in the sense that it does not depend on extrinsic factors like the observer's choice of a coordinate system in which the stimulus is viewed (i.e., the observer's choice of channels and sensors). In other words, the resulting description is an intrinsic property of the evolution of the "real" stimulus that is "out there" broadcasting energy to the observer. This methodology is illustrated with analytic examples and with a numerically simulated experiment. In an intelligent sensory device, this kind of representation "engine" could function as a "front end" that passes channel/sensor-independent stimulus representations to a pattern recognition module. After a pattern recognizer has been trained in one of these devices, it could be used without change in other devices having different channels and sensors.