opencvjs

Complete opencvjs.(With the lastest OpenCV 4.0.0+)

The official opencv.js stoped update. Moreover, it still has many errors from the last offical version.

This project is inherited from official opencv.js.

Which means all of the methods in opencv.js works here, also, fix most of the errors.

But much more performance improved.

Features

• OpenCVJS writen by native JS which means this project can be used directly in the browser or JS project, or node.js
• OpenCVJS is the easiest to install as one .js file
• OpenCVJS has achieved most of the OpenCV C++ functions
• Some of the bad efficient methods implemented on js encapsulate the c++ method directly by using WebAssembly
• Almost every method's performance is faster than total JS implemented
• Performance is acceptted on web real-time face tracking
• The fasttest matix operate functions
• Every funcation is tested

Requirements

• Native JS
• OpenCV 4.0.0+

Communication

• If you found a bug, open an issue.
• If you have a feature request, open an issue.
• If you want to contribute, submit a pull request.

Installation

Javascript

Async invoke opencv.js:

<script async src="opencv.js" onload="onOpenCVReady();" type="text/javascript"></script>

Do coding after onOpenCVReady:

<script type="text/javascript">
    function onOpenCVReady() 
	{  
        //...
      	//do something...
   	}
</script>

---

Usage

Commonly

add()

void cv.add(src1, src2, dst)

( dst = src1 + src2 )

src1 First input mat

src2 Second input mat

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = new cv.Mat();
cv.add(mat1, mat2, dst);
mat1.delete(), mat2.delete();
//Don't forget to delete cv.Mat when you don't want to use it any more.
console.log("dst::" + dst.data32F);//dst::2,4,6,8,10,12,14,16,18

addConstant()

cv.Mat dst = src1.addConstant(constant)

( dst = src1 + constant )

src1 First input mat

constant Constant added to each element.

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.addConstant(10);
mat1.delete();
console.log("dst::" + dst.data32F);//dst::11,12,13,14,15,16,17,18,19

subtract()

void cv.subtract(src1, src2, dst)

( dst = src1 - src2 )

src1 First input mat

src2 Second input mat

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = new cv.Mat();
cv.subtract(mat1, mat2, dst);
mat1.delete(), mat2.delete(); 
//Don't forget to delete cv.Mat when you don't want to use it any more.
console.log("dst::" + dst.data32F);//dst::0,0,0,0,0,0,0,0,0

constantSubtract()

cv.Mat dst = src1.constantSubtract(constant)

( dst = constant - src1 )

constant Constant subtract each element.

src1 First input mat

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.constantSubtract(10);
mat1.delete();
console.log("dst::" + dst.data32F);//dst::9,8,7,6,5,4,3,2,1

mmul()

cv.Mat dst = src1.mul(src2)

( dst = src1 * src2 )

src1 First input mat

src2 Second input mat

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.mmul(mat2);
mat1.delete(), mat2.delete();
console.log("dst::" + dst.data32F);//dst::30,36,42,66,81,96,102,126,150

mul()

cv.Mat dst = src1.mul(src2, scale)

( dst = src1 • src2*scale )

src1 First input mat

src2 Second input mat

scale Optional scale factor.

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.mul(mat2, 2);
mat1.delete(), mat2.delete();
console.log("dst::" + dst.data32F);//dst::2,8,18,32,50,72,98,128,162

mulConstant()

cv.Mat dst = src1.mulConstant(constant)

( dst = src1 * constant )

src1 First input mat

constant Constant added to each element.

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.mulConstant(10);
mat1.delete();
console.log("dst::" + dst.data32F);//dst::10,20,30,40,50,60,70,80,90

divide()

void cv.divide(src1, src2, dst)

( dst = src1 / src1 )

src1 First input mat

src2 Second input mat

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = new cv.Mat();
cv.divide(mat1, mat2, dst);
mat1.delete(), mat2.delete();
console.log("dst::" + dst.data32F);//dst::1,1,1,1,1,1,1,1,1

constantDivide()

cv.Mat dst = src1.constantDivide(constant)

( dst = constant / src1 )

constant Constant subtract each element.

src1 First input mat

dst Output mat that has the same size and number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.constantDivide(10);
mat1.delete();
console.log("dst::" + dst.data32F);
//dst::10,5,3.3333332538604736,2.5,2,1.6666666269302368,1.4285714626312256,1.25,1.1111111640930176

reshape()

Cv.Mat dst = src1.reshape(rows)

src1 First input mat

rows Reshape to rows

dst Output mat that has the same data of src1, but the row is equal to input rows

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.reshape(1);
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::1,2,3,4,5,6,7,8,9:::1:::9
dst.delete();//Don't forget to delete cv.Mat when you don't want to use it any more.

sum()

Float dst = src1.sum()

src1 First input mat

dst Sum of src1 data

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let sum = mat1.sum();
mat1.delete();
console.log("dst::" + dst);//dst::45

norm()

Float dst = cv.norm(src1)

src1 First input mat

dst Norm of src1

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = cv.norm(mat1);
mat1.delete();
console.log("dst::" + dst);//dst::16.881943016134134

norm2()

Float dst = cv.norm(src1, src2)

src1 First input mat

src2 Second input mat

dst Norm of src1 and src2

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[9,10,11,12,13,14,15,16,17]);
let dst2 = cv.norm2(mat1, mat2);
mat1.delete(), mat2.delete();
console.log("dst2::" + dst2);//dst2::24

Diag()

cv.Mat dst = src1.diag(d = 0)

src1 First input mat

d Index of the diagonal

dst Output mat that has the same data of src1, but the row is equal to input rows

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.Diag();
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::1,5,9:::3:::1

vconcat()

cv.Mat dst = src1.vconcat(src2)

src1 First input mat

src2 Second input mat has the same cols as the first input mat

dst Output mat that has the same number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.vconcat(mat1);
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9:::6:::3

hconcat()

cv.Mat dst = src1.hconcat(src2)

src1 First input mat

src2 Second input mat has the same rows as the first input mat

dst Output mat that has the same number of channels as the input mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.hconcat(mat1);
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::1,2,3,1,2,3,4,5,6,4,5,6,7,8,9,7,8,9:::3:::6

row()

cv.Mat dst = src1.row(row)

src1 First input mat

row Index of the rows

dst Output mat that has one row

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.row(2);
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::7,8,9:::1:::3

col()

cv.Mat dst = src1.col(col)

src1 First input mat

col Index of the cols

dst Output mat that has one col

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.col(2);
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::3,6,9:::3:::1

replaceMatOnRect()

void src1.replaceMatOnRect(src2, rect)

src1 First input mat will be changed as output

src2 Second input mat as rect mat

rect rect input to replace

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let rect1 = new cv.Rect(1, 1, 2, 2);
let rectmat = cv.matFromArray(2,2,cv.CV_32FC1,[11,12,13,14]);
mat1.replaceMatOnRect(rectmat, rect1);
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,2,3,4,11,12,7,13,14:::3:::3

replaceMatOnRow()

void src1.replaceMatOnRow(arr, row)

src1 First input mat will be changed as output

arr Second input Array as row array

row row input to replace

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
mat1.replaceMatOnRow([11,12,13], 1);
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,2,3,11,12,13,7,8,9:::3:::3

replaceMatOnCol()

void src1.replaceMatOnCol(arr, col)

src1 First input mat will be changed as output

arr Second input Array as row array

col col input to replace

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
mat1.replaceMatOnCol([11,12,13], 1);
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,11,3,4,12,6,7,13,9:::3:::3

replaceMatOnPoint()

void src1.replaceMatOnPoint(constant, point)

src1 First input mat will be changed as output

constant Second input constant tp replace at the point

point Point location

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
mat1.replaceMatOnPoint(30, {x:1,y:1});
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,11,3,4,12,6,7,13,9:::3:::3

addOnCol()

void src1.addOnCol(constant, col)

src1 First input mat will be changed as output

constant Second input constant tp replace at the point

col Col location

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
mat1.addOnCol(30, 1);
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,11,3,4,12,6,7,13,9:::3:::3

rectAdd()

void src1.rectAdd(src2, rect)

src1 First input mat will be changed as output

src2 Second input mat as rect mat

rect rect input to add location

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let rect1 = new cv.Rect(1, 1, 2, 2);
let rectmat = cv.matFromArray(2,2,cv.CV_32FC1,[11,12,13,14]);
mat1.rectAdd(rectmat, rect1);
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,2,3,4,11,12,7,13,14:::3:::3

rectSubtract()

void src1.rectSubtract(src2, rect)

src1 First input mat will be changed as output

src2 Second input mat as rect mat

rect rect input to subtract location

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let rect1 = new cv.Rect(1, 1, 2, 2);
let rectmat = cv.matFromArray(2,2,cv.CV_32FC1,[11,12,13,14]);
mat1.rectSubtract(rectmat, rect1);
console.log("mat1::" + mat1.data32F + ":::" + mat1.rows + ":::" + mat1.cols);
//mat1::1,2,3,4,11,12,7,13,14:::3:::3

mds()

{m:Float, d:Array, s:Float} dst = src1.mds()

src1 First input mat

dst Output with {mean, dev, stddev}

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.mds();
mat1.delete();
console.log("dst::" + dst.m + ":::" + dst.d + ":::" + dst.s);
//dst::5:::16,9,4,1,0,1,4,9,16:::2.581988897471611

roi()

Cv.Mat dst = src1.roi(rect)

src1 First input mat

rect a rect

dst Output mat that has the same size and number of channels as the input rect

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let rect1 = new cv.Rect(1, 1, 2, 2)
let dst = mat1.roi(rect1);
mat1.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::5,6,8,9:::2:::2

svd()

{u:cv.Mat, w:cv.Mat, vt:cv.Mat} dst = src1.svd()

src1 First input mat

dst Output with {u, w, vt}

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let s = mat1.svd();
mat1.delete();
console.log("sssss::" + s.u.data32F + ":::" + s.w.data32F + "::::" + s.vt.data32F);
//sssss::-0.2690670727222803,-0.6798212121523656,-0.6822360514399335,0.9620092303255996,-0.15566952916310073,-0.22428829318197974,-0.04627257443681115,0.7166659732384585,-0.6958798255856847:::817.7596679296927,2.4749744909160456,0.002964523081211532::::0.6822778524193859,-0.6671413517114333,-0.29903068226292867,0.22871202334807922,-0.19371852220929917,0.9540251278289649,0.6943973952097016,0.7193021277527875,-0.020413391102276603

RodriguesFromArray()

cv.Mat dst = cv.RodriguesFromArray(arr1)

arr1 First input array

dst the mat rodrigues from the input array

let arr1 = [1,2,3,4,5,6,7,8,9];
let dst = cv.RodriguesFromArray(arr1);
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::-0.694920539855957,0.7135210037231445,0.08929285407066345,-0.19200697541236877,-0.3037850260734558,0.9331923723220825,0.6929781436920166,0.6313496828079224,0.34810739755630493:::3:::3

RodriguesFromMat()

[x, y, z] dst = src1.RodriguesFromMat()

src1 First input mat

dst the mat rodrigues from the input array

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.RodriguesFromMat();
console.log("dst::" + dst);
//dst::1.1046628653680794,1.738419705279746,2.372176486533247

dftSplit()

{r:realMat, i:imagMat} dst = src1.dftSplit()

src1 First input mat

dst the mat rodrigues from the input array

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let dst = mat1.dftSplit();
console.log("dst::" + dst.r.data32F + ":::" + dst.i.data32F);
//dst::1,3,0,4,6,0,0,8,0:::0,3,0,7,9,0,0,9,0

mulSpectrums()

cv.Mat dst = cv.mulSpectrums(src1, src2, conjB = false)

src1 First input mat

src2 Second input mat

conjB Default is false

dst Result of mat

let mat1 = cv.matFromArray(3,3,cv.CV_32FC1,[1,2,3,4,5,6,7,8,9]);
let mat2 = cv.matFromArray(3,3,cv.CV_32FC1,[9,10,11,12,13,14,15,16,17]);
let dst = cv.mulSpectrums(mat1, mat2, true);
mat1.delete(), mat2.delete();
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols);
//dst::9,8.96831017167883e-44,66,153,4.624284932271896e-44,237,NaN,1.2534558711446916e-39,NaN:::3:::3

mulSpectrums2Channel()

cv.Mat dst = cv.mulSpectrums2Channel(src1, src2, conjB = false)

src1 First input mat

src2 Second input mat

conjB Default is false

dst Result of mat

let mat1_2channels = cv.matFromArray(3,3,cv.CV_32FC2,[1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9]);
let mat2_2channels = cv.matFromArray(3,3,cv.CV_32FC2,[9,10,11,12,13,14,15,16,17,9,10,11,12,13,14,15,16,17]);
let dst = cv.mulSpectrums2Channel(mat1_2channels, mat2_2channels, true);
console.log("dst::" + dst.data32F + ":::" + dst.rows + ":::" + dst.cols + ":::" + dst.channels());
//dst::29,8.96831017167883e-44,81,233,4.624284932271896e-44,162,NaN,1.2534558711446916e-39,NaN:::3:::3:::1

Others

default constructor

let mat = new cv.Mat();
let mat = new cv.Mat(size, type);
let mat = new cv.Mat(rows, cols, type);
let mat = new cv.Mat(rows, cols, type, new cv.Scalar());
let mat = cv.matFromArray(rows, cols, type, array);

let ctx = canvas.getContext("2d");
let imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
let mat = cv.matFromImageData(imgData);

let mat = cv.Mat.zeros(rows, cols, type);
let mat = cv.Mat.ones(rows, cols, type);
let mat = cv.Mat.eye(rows, cols, type);

copy Mat

let dst = src.clone();
src.copyTo(dst, mask);

convert type

src.convertTo(m, rtype, alpha = 1, beta = 0);

MatVector

let mat = new cv.Mat();
let matVec = new cv.MatVector();
matVec.push_back(mat);
let cnt = matVec.get(0);
mat.delete(); matVec.delete(); cnt.delete();

data

[Data Properties]	[C++ Type]	[JavaScript Typed Array]	[Mat Type]
data				uchar		Uint8Array					CV_8U
data8S				char		Int8Array					CV_8S
data16U				ushort		Uint16Array					CV_16U
data16S				short		Int16Array					CV_16S
data32S				int			Int32Array					CV_32S
data32F				float		Float32Array				CV_32F
data64F				double		Float64Array				CV_64F

// row = 3, col = 4, channels = 4
let R = src.data[row * src.cols * src.channels() + col * src.channels()];
let G = src.data[row * src.cols * src.channels() + col * src.channels() + 1];
let B = src.data[row * src.cols * src.channels() + col * src.channels() + 2];
let A = src.data[row * src.cols * src.channels() + col * src.channels() + 3];

at

[Mat Type]		[At Manipulation]
CV_8U			ucharAt
CV_8S			charAt
CV_16U			ushortAt
CV_16S			shortAt
CV_32S			intAt
CV_32F			floatAt
CV_64F			doubleAt

//row = 3, col = 4, channels = 4
let R = src.ucharAt(row, col * src.channels());
let G = src.ucharAt(row, col * src.channels() + 1);
let B = src.ucharAt(row, col * src.channels() + 2);
let A = src.ucharAt(row, col * src.channels() + 3);

ptr

[Mat Type]		[Ptr Manipulation]		[JavaScript Typed Array]
CV_8U			ucharPtr				Uint8Array
CV_8S			charPtr					Int8Array
CV_16U			ushortPtr				Uint16Array
CV_16S			shortPtr				Int16Array
CV_32S			intPtr					Int32Array
CV_32F			floatPtr				Float32Array
CV_64F			doublePtr				Float64Array

//row = 3, col = 4, channels = 4
let pixel = src.ucharPtr(row, col);
let R = pixel[0];
let G = pixel[1];
let B = pixel[2];
let A = pixel[3];

Bitwise Operations

cv.bitwise_not();
cv.bitwise_and();
cv.bitwise_or();
cv.bitwise_xor();

Point

let point = new cv.Point(x, y);
let point = {x: x, y: y};

Scalar

let scalar = new cv.Scalar(R, G, B, Alpha);
let scalar = [R, G, B, Alpha];

Size

let size = new cv.Size(width, height);
let size = {width : width, height : height};

Circle

let circle = new cv.Circle(center, radius);
let circle = {center : center, radius : radius};

Rect

let rect = new cv.Rect(x, y, width, height);
let rect = {x : x, y : y, width : width, height : height};

RotatedRect

let rotatedRect = new cv.RotatedRect(center, size, angle);
let rotatedRect = {center : center, size : size, angle : angle};

let vertices = cv.RotatedRect.points(rotatedRect);
let point1 = vertices[0];
let point2 = vertices[1];
let point3 = vertices[2];
let point4 = vertices[3];

let boundingRect = cv.RotatedRect.boundingRect(rotatedRect);

cvtColor

cv.cvtColor(src, dst, cv.COLOR_RGBA2GRAY, 0);

inRange

cv.inRange(src, low, high, dst);

Scaling

cv.resize (src, dst, dsize, fx = 0, fy = 0, interpolation = cv.INTER_LINEAR)

Translation

cv.warpAffine (src, dst, M, dsize, flags = cv.INTER_LINEAR, borderMode = cv.BORDER_CONSTANT, borderValue = new cv.Scalar())

Rotation

cv.getRotationMatrix2D (center, angle, scale)

Affine Transformation

cv.getAffineTransform (src, dst)

Perspective Transformation

let M = cv.getPerspectiveTransform(srcTri, dstTri);
cv.warpPerspective(src, dst, M, dsize, cv.INTER_LINEAR, cv.BORDER_CONSTANT, new cv.Scalar());

Simple Thresholding

cv.threshold(src, dst, 177, 200, cv.THRESH_BINARY);

Adaptive Thresholding

//cv.adaptiveThreshold (src, dst, maxValue, adaptiveMethod, thresholdType, blockSize, C)
cv.adaptiveThreshold(src, dst, 200, cv.ADAPTIVE_THRESH_GAUSSIAN_C, cv.THRESH_BINARY, 3, 2);

2D Convolution ( Image Filtering )

//cv.filter2D (src, dst, ddepth, kernel, anchor = new cv.Point(-1, -1), delta = 0, borderType = cv.BORDER_DEFAULT)
cv.filter2D(src, dst, cv.CV_8U, M, anchor, 0, cv.BORDER_DEFAULT);

Image Blurring (Image Smoothing)

//cv.blur (src, dst, ksize, anchor = new cv.Point(-1, -1), borderType = cv.BORDER_DEFAULT)
cv.blur(src, dst, ksize, anchor, cv.BORDER_DEFAULT);

//cv.boxFilter (src, dst, ddepth, ksize, anchor = new cv.Point(-1, -1), normalize = true, borderType = cv.BORDER_DEFAULT)
cv.boxFilter(src, dst, -1, ksize, anchor, true, cv.BORDER_DEFAULT)

//cv.GaussianBlur (src, dst, ksize, sigmaX, sigmaY = 0, borderType = cv.BORDER_DEFAULT)
cv.GaussianBlur(src, dst, ksize, 0, 0, cv.BORDER_DEFAULT);

//cv.medianBlur (src, dst, ksize)
cv.medianBlur(src, dst, 5);

//cv.bilateralFilter (src, dst, d, sigmaColor, sigmaSpace, borderType = cv.BORDER_DEFAULT)
cv.bilateralFilter(src, dst, 9, 75, 75, cv.BORDER_DEFAULT);

Erosion

//cv.erode (src, dst, kernel, anchor = new cv.Point(-1, -1), iterations = 1, borderType = cv.BORDER_CONSTANT, borderValue = cv.morphologyDefaultBorderValue())
cv.erode(src, dst, M, anchor, 1, cv.BORDER_CONSTANT, cv.morphologyDefaultBorderValue());

Dilation

//cv.dilate (src, dst, kernel, anchor = new cv.Point(-1, -1), iterations = 1, borderType = cv.BORDER_CONSTANT, borderValue = cv.morphologyDefaultBorderValue())
cv.dilate(src, dst, M, anchor, 1, cv.BORDER_CONSTANT, cv.morphologyDefaultBorderValue());

Opening

//cv.morphologyEx (src, dst, op, kernel, anchor = new cv.Point(-1, -1), iterations = 1, borderType = cv.BORDER_CONSTANT, borderValue = cv.morphologyDefaultBorderValue())
cv.morphologyEx(src, dst, cv.MORPH_OPEN, M, anchor, 1, cv.BORDER_CONSTANT, cv.morphologyDefaultBorderValue());

Closing

cv.morphologyEx(src, dst, cv.MORPH_CLOSE, M);

Morphological Gradient

cv.morphologyEx(src, dst, cv.MORPH_GRADIENT, M);

Top Hat

cv.morphologyEx(src, dst, cv.MORPH_TOPHAT, M);

Black Hat

cv.morphologyEx(src, dst, cv.MORPH_BLACKHAT, M);

Structuring Element

//cv.getStructuringElement (shape, ksize, anchor = new cv.Point(-1, -1))
M = cv.getStructuringElement(cv.MORPH_CROSS, ksize);
cv.morphologyEx(src, dst, cv.MORPH_GRADIENT, M);

Sobel and Scharr Derivatives

//cv.Sobel (src, dst, ddepth, dx, dy, ksize = 3, scale = 1, delta = 0, borderType = cv.BORDER_DEFAULT)
cv.Sobel(src, dstx, cv.CV_8U, 1, 0, 3, 1, 0, cv.BORDER_DEFAULT);

//cv.Scharr (src, dst, ddepth, dx, dy, scale = 1, delta = 0, borderType = cv.BORDER_DEFAULT)
cv.Scharr(src, dstx, cv.CV_8U, 1, 0, 1, 0, cv.BORDER_DEFAULT);

Laplacian Derivatives

//cv.Laplacian (src, dst, ddepth, ksize = 1, scale = 1, delta = 0, borderType = cv.BORDER_DEFAULT)
cv.Laplacian(src, dst, cv.CV_8U, 1, 1, 0, cv.BORDER_DEFAULT);

Image AbsSobel

cv.Sobel(src, dstx, cv.CV_8U, 1, 0, 3, 1, 0, cv.BORDER_DEFAULT);
cv.Sobel(src, absDstx, cv.CV_64F, 1, 0, 3, 1, 0, cv.BORDER_DEFAULT);
cv.convertScaleAbs(absDstx, absDstx, 1, 0);

draw the contours

//cv.findContours (image, contours, hierarchy, mode, method, offset = new cv.Point(0, 0))
cv.findContours(src, contours, hierarchy, cv.RETR_CCOMP, cv.CHAIN_APPROX_SIMPLE);

//cv.drawContours (image, contours, contourIdx, color, thickness = 1, lineType = cv.LINE_8, hierarchy = new cv.Mat(), maxLevel = INT_MAX, offset = new cv.Point(0, 0))
cv.drawContours(dst, contours, i, color, 1, cv.LINE_8, hierarchy, 100);

Moments

//cv.moments (array, binaryImage = false)
let Moments = cv.moments(cnt, false);

Contour Area

//cv.contourArea (contour, oriented = false)
let area = cv.contourArea(cnt, false);

Contour Perimeter

//cv.arcLength (curve, closed)
let perimeter = cv.arcLength(cnt, true);

Contour Approximation

//cv.approxPolyDP (curve, approxCurve, epsilon, closed)
cv.approxPolyDP(cnt, tmp, 3, true);

Convex Hull

//cv.convexHull (points, hull, clockwise = false, returnPoints = true)
cv.convexHull(cnt, tmp, false, true);

Checking Convexity

cv.isContourConvex(cnt);

Straight Bounding Rectangle

//cv.boundingRect (points)
let rect = cv.boundingRect(cnt);

Rotated Rectangle

//cv.minAreaRect (points)
let rotatedRect = cv.minAreaRect(cnt);

Minimum Enclosing Circle

//cv.minEnclosingCircle (points)
let circle = cv.minEnclosingCircle(cnt);

//cv.circle (img, center, radius, color, thickness = 1, lineType = cv.LINE_8, shift = 0)
cv.circle(dst, circle.center, circle.radius, circleColor);

Fitting an Ellipse

//cv.fitEllipse (points)
let rotatedRect = cv.fitEllipse(cnt);

//cv.ellipse1 (img, box, color, thickness = 1, lineType = cv.LINE_8)
cv.ellipse1(dst, rotatedRect, ellipseColor, 1, cv.LINE_8);

Fitting a Line

//cv.fitLine (points, line, distType, param, reps, aeps)
cv.fitLine(cnt, line, cv.DIST_L2, 0, 0.01, 0.01);

//cv.line (img, pt1, pt2, color, thickness = 1, lineType = cv.LINE_8, shift = 0)
cv.line(dst, point1, point2, lineColor, 2, cv.LINE_AA, 0);

Aspect Ratio

let rect = cv.boundingRect(cnt);
let aspectRatio = rect.width / rect.height;

Extent

let area = cv.contourArea(cnt, false);
let rect = cv.boundingRect(cnt));
let rectArea = rect.width * rect.height;
let extent = area / rectArea;

Solidity

let area = cv.contourArea(cnt, false);
cv.convexHull(cnt, hull, false, true);
let hullArea = cv.contourArea(hull, false);
let solidity = area / hullArea;

Equivalent Diameter

let area = cv.contourArea(cnt, false);
let equiDiameter = Math.sqrt(4 * area / Math.PI);

Orientation

let rotatedRect = cv.fitEllipse(cnt);
let angle = rotatedRect.angle;

Mask and Pixel Points

//cv.transpose (src, dst)
cv.transpose(src, dst);

Maximum Value, Minimum Value and their locations

//cv.minMaxLoc(src, mask)
let result = cv.minMaxLoc(src, mask);
let minVal = result.minVal;
let maxVal = result.maxVal;
let minLoc = result.minLoc;
let maxLoc = result.maxLoc;

Mean Color or Mean Intensity

cv.mean (src, mask)

Convexity Defects

//cv.convexityDefects (contour, convexhull, convexityDefect)
cv.convexityDefects(cnt, hull, defect);

Point Polygon Test

//cv.pointPolygonTest (contour, pt, measureDist)
let dist = cv.pointPolygonTest(cnt, new cv.Point(50, 50), true);

Match Shapes

//cv.matchShapes (contour1, contour2, method, parameter)
let result = cv.matchShapes(contours.get(contourID0), contours.get(contourID1), 1, 0);

Find Histogram

//cv.calcHist (image, channels, mask, hist, histSize, ranges, accumulate = false)
cv.calcHist(srcVec, channels, mask, hist, histSize, ranges, accumulate);

Histograms Equalization

cv.equalizeHist (src, dst)

CLAHE (Contrast Limited Adaptive Histogram Equalization)

//cv.CLAHE (clipLimit = 40, tileGridSize = new cv.Size(8, 8))
let clahe = new cv.CLAHE(40, tileGridSize);

Backprojection

//cv.calcBackProject (images, channels, hist, dst, ranges, scale)
cv.calcBackProject(dstVec, channels, hist, backproj, ranges, 1);

//cv.normalize (src, dst, alpha = 1, beta = 0, norm_type = cv.NORM_L2, dtype = -1, mask = new cv.Mat())
cv.normalize(hist, hist, 0, 255, cv.NORM_MINMAX, -1, none);

Fourier Transform

//cv.dft (src, dst, flags = 0, nonzeroRows = 0)
cv.dft(complexI, complexI);

//cv.getOptimalDFTSize (vecsize)
let optimalRows = cv.getOptimalDFTSize(src.rows);

//cv.copyMakeBorder (src, dst, top, bottom, left, right, borderType, value = new cv.Scalar())
cv.copyMakeBorder(src, padded, 0, optimalRows - src.rows, 0, optimalCols - src.cols, cv.BORDER_CONSTANT, s0);

//cv.magnitude (x, y, magnitude)
cv.magnitude(planes.get(0), planes.get(1), planes.get(0));

//cv.split (m, mv)
cv.split(complexI, planes);

//cv.merge (mv, dst)
cv.merge(planes, complexI);

Template Matching

//cv.matchTemplate (image, templ, result, method, mask = new cv.Mat())
cv.matchTemplate(src, templ, dst, cv.TM_CCOEFF, mask);

Hough Transform

//cv.HoughLines (image, lines, rho, theta, threshold, srn = 0, stn = 0, min_theta = 0, max_theta = Math.PI)
cv.HoughLines(src, lines, 1, Math.PI / 180, 30, 0, 0, 0, Math.PI);

Probabilistic Hough Transform

//cv.HoughLinesP (image, lines, rho, theta, threshold, minLineLength = 0, maxLineGap = 0)
cv.HoughLinesP(src, lines, 1, Math.PI / 180, 2, 0, 0);

Hough Circle Transform

//cv.HoughCircles (image, circles, method, dp, minDist, param1 = 100, param2 = 100, minRadius = 0, maxRadius = 0)
cv.HoughCircles(src, circles, cv.HOUGH_GRADIENT, 1, 45, 75, 40, 0, 0);

Threshold

cv.threshold(gray, gray, 0, 255, cv.THRESH_BINARY_INV + cv.THRESH_OTSU);

Distance Transform

//cv.distanceTransform (src, dst, distanceType, maskSize, labelType = cv.CV_32F)
cv.distanceTransform(opening, distTrans, cv.DIST_L2, 5);

mage Watershed

//cv.connectedComponents (image, labels, connectivity = 8, ltype = cv.CV_32S)
cv.connectedComponents(coinsFg, markers);

//cv.watershed (image, markers)
cv.watershed(src, markers);

Foreground Extraction

//cv.grabCut (image, mask, rect, bgdModel, fgdModel, iterCount, mode = cv.GC_EVAL)
cv.grabCut(src, mask, rect, bgdModel, fgdModel, 1, cv.GC_INIT_WITH_RECT);

Meanshift

//cv.meanShift (probImage, window, criteria)
[, trackWindow] = cv.meanShift(dst, trackWindow, termCrit);

Camshift

//cv.CamShift (probImage, window, criteria)
[trackBox, trackWindow] = cv.CamShift(dst, trackWindow, termCrit);

Lucas-Kanade Optical Flow

//cv.calcOpticalFlowPyrLK (prevImg, nextImg, prevPts, nextPts, status, err, winSize = new cv.Size(21, 21), maxLevel = 3, criteria = new cv.TermCriteria(cv.TermCriteria_COUNT+ cv.TermCriteria_EPS, 30, 0.01), flags = 0, minEigThreshold = 1e-4)
let criteria = new cv.TermCriteria(cv.TERM_CRITERIA_EPS | cv.TERM_CRITERIA_COUNT, 10, 0.03);
cv.calcOpticalFlowPyrLK(oldGray, frameGray, p0, p1, st, err, winSize, maxLevel, criteria);

Dense Optical Flow

//cv.calcOpticalFlowFarneback (prev, next, flow, pyrScale, levels, winsize, iterations, polyN, polySigma, flags)
cv.calcOpticalFlowFarneback(prvs, next, flow, 0.5, 3, 15, 3, 5, 1.2, 0);

BackgroundSubtractorMOG2

//cv.BackgroundSubtractorMOG2 (history = 500, varThreshold = 16, detectShadows = true)
let fgbg = new cv.BackgroundSubtractorMOG2(500, 16, true);

//cv.apply (image, fgmask, learningRate = -1)
fgbg.apply(frame, fgmask);

Haar-cascade Detection

//detectMultiScale (image, objects, scaleFactor = 1.1, minNeighbors = 3, flags = 0, minSize = new cv.Size(0, 0), maxSize = new cv.Size(0, 0))
let faceCascade = new cv.CascadeClassifier();
faceCascade.load('haarcascade_frontalface_default.xml');
faceCascade.detectMultiScale(gray, faces, 1.1, 3, 0, msize, msize);

image && video

cv.imread();
cv.imshow();
cv.VideoCapture();

other

cv.rectangle();
cv.Canny();
cv.goodFeaturesToTrack();
cv.cartToPolar();
cv.randu();
new cv.ORB();

To Do List

• Performance, up speed performance.
• Methods complete all the opencv functions.

License

OpenCVJS is released under the MIT license. See LICENSE for details.