opencv-basics

Simple demonstrations of basic use of OpenCV

Documentation (3.2) Links

Structures

• Affine3
• Mat
• Rect
• Size
• RotatedRect

• Image Processing
  • Image Filtering
    • blur
    • dilate
    • erode
    • GaussianBlur
  • Geometric Image Transformations
    • getAffineTransform
    • getDefaultNewCameraMatrix
    • getPerspectiveTransform
    • getRectSubPix
    • remap
    • resize
    • undistort
    • undistortPoints
    • warpAffine
    • warpPerspective
  • Miscellaneous Image Transformation
    • adaptiveThreshold
    • cvtColor
    • threshold
  • Drawing Functions
    • drawContours
  • Color Maps in OpenCV
    • applyColorMap
  • Histograms
    • calcBackProject
    • calcHist
    • compareHist
    • equalizeHist
  • Structural Analysis and Shape Descriptors
    • findContours
    • approxPolyDP
    • arcLength
    • contourArea
    • pointPolygonTest
    • HuMoments
  • Motion Analysis and Object Tracking
    • phaseCorrelate
  • Feature Detection
    • Canny
    • cornerHarris
    • goodFeaturesToTrack
    • HoughLines
  • Object Detection
    • matchTemplate
• Calib3d
  • Camera Calibration and 3D Reconstruction
    • calibrateCamera
    • findChessboardCorners

3D to 2D Projection Equation

Many of the functions of the calib3d module relate to the pinhole camera model found in the Detailed Description on the Camera Calibration page and below. Often, you'll have some of the values and want to know which function to use to solve for the unknown. The table below shows inputs in italic and outputs in bold.

  | u |    | fx   0  cx || R R R Tx|| X |
s | v |  = |  0  fy  cy || R R R Ty|| Y |
  | 1 |    |  0   0   1 || R R R Tz|| Z |
                                    | 1 |

Function	objPts	pts1/2	M	distort	R	T	E	F	H	R1/R2	P1/P2	Q	misc
calib3d
calibrateCamera	X	1	X	X	X	X
projectPoints	X	1	X	X	X	X
stereoCalibrate	X	1&2	1&2	1&2	X	X	X	X
findEssentialMat		1&2	foc/pp				X
findFundamentalMat		1&2						X
findHomography		1&2							X
stereoRectify			1&2	1&2	X	X				1&2	1&2	X
stereoRectifyUncalibrated		1&2						X	1&2
computeCorrespondEpilines		1						X
reprojectImageTo3D		disparity										X	image3d
decomposeEssentialMat					1&2	X	X
decomposeHomographyMat			X(K)		multiple	multiple			X
decomposeProjectionMatrix			X		X	X					P
recoverPose		1&2	foc/pp		X	X	X
triangulatePoints		1&2									P1&P2		points4D
solvePnP	X	1	X	X	X	X
solvePnPRansac	X	1	X	X	X	X
core Operations on Arrays
perspectiveTransform		X							X				points
Function	objPts	pts1/2	M	distort	R	T	E	F	H	R1/R2	P1/P2	Q	misc
imgproc Geometric Image Transformations
initUndistortRectifyMap			X	X						X	X		mapx/y
remap		srcImg											mapx/ydstImg
undistort		srcImg	X	X									dstImg
undistortPoints		X	X	X						X	X		points
warpPerspective		srcImg							X				dstImg

Mat Types

Type	C1	C2	C3	C4
CV_8U	0	8	16	24
CV_8S	1	9	17	25
CV_16U	2	10	18	26
CV_16S	3	11	19	27
CV_32S	4	12	20	28
CV_32F	5	13	21	29
CV_64F	6	14	22	30