cv2.calcOpticalFlowPyrLK

Raw wrapper of cv2.calcOpticalFlowPyrLK(prevImg, nextImg, prevPts, nextPts, winSize?, maxLevel?, criteria?, flags?, minEigThreshold?). Parameters marked '?' are optional; blank means OpenCV default. See the OpenCV documentation for details.

By bmad4ever·Created 3 months ago·Updated 2 days ago· 0

prevImg
nextImg
prevPts
nextPts
winSize

nextPts
status
err

◄maxLevel3►

◄criteria_typemax count or epsilon (whichever first)►

◄criteria_max_count30►

◄criteria_epsilon0.00►

◄flagsnone (0)►

◄minEigThreshold0.0001►

Categoryimage/CV/low-level/cv2 C

Inputs (11)

Name	Type	Default	Description
prevImg	NPARRAY,IMAGE,MASK		first 8-bit input image or pyramid constructed by buildOpticalFlowPyramid. Accepts a ComfyUI IMAGE/MASK directly (frame 0 of a batch) or an NPARRAY. Arithmetic ops (add, multiply, etc.) process the full IMAGE batch when both inputs have the same batch size.
nextImg	NPARRAY,IMAGE,MASK		second input image or pyramid of the same size and the same type as prevImg. Accepts a ComfyUI IMAGE/MASK directly (frame 0 of a batch) or an NPARRAY. Arithmetic ops (add, multiply, etc.) process the full IMAGE batch when both inputs have the same batch size.
prevPts	NPARRAY		vector of 2D points for which the flow needs to be found; point coordinates must be single-precision floating-point numbers. A data array (points / matrix), NOT an image - only an NPARRAY link is accepted here.
nextPts	NPARRAY		output vector of 2D points (with single-precision floating-point coordinates) containing the calculated new positions of input features in the second image; when OPTFLOW_USE_INITIAL_FLOW flag is passed, the vector must have the same size as in the input. A data array (points / matrix), NOT an image - only an NPARRAY link is accepted here.
winSizeopt	CV_TUPLE	0,0	size of the search window at each pyramid level. One value with 2 components (w, h) - it travels as a whole, so it cannot arrive half-connected. Wire it from 'CV Tuple' or type the components in place.
maxLevelopt	INT	3-2147483648–2147483647	0-based maximal pyramid level number; if set to 0, pyramids are not used (single level), if set to 1, two levels are used, and so on; if pyramids are passed to input then algorithm will use as many levels as pyramids have but no more than maxLevel. Preset to the OpenCV default (3).
criteria_typeopt	COMBO	max count or epsilon (whichever first)	When to stop iterating: after max_count iterations, when the change drops below epsilon, or whichever comes first.
criteria_max_countopt	INT	301–2147483647	Maximum iterations (ignored when 'epsilon only').
criteria_epsilonopt	FLOAT	0.000–1e+38	Target accuracy / smallest change worth continuing for (ignored when 'max count only').
flagsopt	STRING	none (0)	operation flags: - OPTFLOW_USE_INITIAL_FLOW uses initial estimations, stored in nextPts; if the flag is not set, then prevPts is copied to nextPts and is considered the initial estimate. - OPTFLOW_LK_GET_MIN_EIGENVALS use minimum eigen values as an error measure (see minEigThreshold description); if the flag is not set, then L1 distance between patches around the original and a moved point, divided by number of pixels in a window, is used as a error measure. cv2.calcOpticalFlowPyrLK flags: one of none (0) plus any of OPTFLOW_USE_INITIAL_FLOW, OPTFLOW_LK_GET_MIN_EIGENVALS, pipe-joined (e.g. "none (0) \| OPTFLOW_USE_INITIAL_FLOW"). In the UI this renders as a dropdown with one toggle per flag.
minEigThresholdopt	FLOAT	0.0001-1e+38–1e+38	the algorithm calculates the minimum eigen value of a 2x2 normal matrix of optical flow equations (this matrix is called a spatial gradient matrix in ), divided by number of pixels in a window; if this value is less than minEigThreshold, then a corresponding feature is filtered out and its flow is not processed, so it allows to remove bad points and get a performance boost. The function implements a sparse iterative version of the Lucas-Kanade optical flow in pyramids. See Preset to the OpenCV default (0.0001).

Outputs (3)

Name	Type	Description
nextPts	NPARRAY	—
status	NPARRAY	—
err	NPARRAY	—