2013Shigematsu H Noisemodels
Shigematsu H, Sigworth FJ.Noise models and cryo-EM drift correction with a direct-electron camera.U ltramicroscopy. 2013 Aug;131:61-9.
Blurring due to specimen-holder drift is a common occurrence in cryo-EM images. Cameras employing active-pixel sensors are capable of high frame rates such that a single low-dose exposure can be acquired as a series of frames. In this paper we consider the possibility of tracking and compensating for overall drift in typical single-particle specimens through the analysis of frame sequences. A problem that arises in tracking through cross-correlation of frames obtained with the DE-12 camera from Direct Electron LLC is the presence of "hot-pixel noise". This random pattern of bright pixels is highly correlated among frames. We show how a model of this noise can be employed to greatly reduce its effects. A filter function is derived that optimizes the tracking of image shifts by cross-correlation, and we demonstrate the tracking of specimen drift in typical cryo-EM specimens.
"Hot pixel noise" in Direct Detectors (DE-12)