In part, the invention relates to systems and methods of calibrating a plurality of frames generated with respect to a blood vessel as a result of a pullback of an intravascular imaging probe being pullback through the vessel. A calibration feature disposed in the frames that changes between a subset of the frames can be used to perform calibration. Calibration can be performed post-pullback. Various filters and image processing techniques can be used to identify one or more feature in the frames including, without limitation, a calibration feature, a guidewire, a side branch, a stent strut, a lumen of the blood vessel, and other features. The feature can be displayed using a graphic user interface.