Merge pull request #459 from piercus/dct

Direct Cosine Transform implemntation and example

examples/mat-dct.js

@@ -0,0 +1,22 @@
+var cv = require('../lib/opencv');
+
+cv.readImage("./files/mona.png", function(err, orig) {
+  if (err) throw err;
+
+  var chan1 = orig.split()[0];
+
+  var floatInputMatrix = new cv.Matrix();
+  chan1.convertTo(floatInputMatrix, cv.Constants.CV_32F)
+
+  var foatAfterDct = floatInputMatrix.dct();
+
+  // for inverse dct, set argument to "true"
+  var afterDoubleDct = foatAfterDct.dct(true);
+
+  var intOutImage = new cv.Matrix();
+
+  afterDoubleDct.convertTo(intOutImage, cv.Constants.CV_8U);
+  intOutImage.save("./tmp/dct.png");
+  console.log('Image saved to ./tmp/dct.png');
+
+});

src/Matrix.cc

@@ -65,6 +65,7 @@ void Matrix::Init(Local<Object> target) {
   Nan::SetPrototypeMethod(ctor, "roi", ROI);
   Nan::SetPrototypeMethod(ctor, "ptr", Ptr);
   Nan::SetPrototypeMethod(ctor, "absDiff", AbsDiff);
+  Nan::SetPrototypeMethod(ctor, "dct", Dct);
   Nan::SetPrototypeMethod(ctor, "addWeighted", AddWeighted);
   Nan::SetPrototypeMethod(ctor, "bitwiseXor", BitwiseXor);
   Nan::SetPrototypeMethod(ctor, "bitwiseNot", BitwiseNot);
@@ -1277,6 +1278,24 @@ NAN_METHOD(Matrix::AbsDiff) {
   info.GetReturnValue().Set(Nan::Null());
 }
 
+NAN_METHOD(Matrix::Dct) {
+  Nan::HandleScope scope;
+
+  Matrix *self = Nan::ObjectWrap::Unwrap<Matrix>(info.This());
+  int cols = self->mat.cols;
+  int rows = self->mat.rows;
+
+  bool inverse = info[1]->ToBoolean()->Value();
+
+  Local<Object> out = Nan::New(Matrix::constructor)->GetFunction()->NewInstance();
+  Matrix *m_out = Nan::ObjectWrap::Unwrap<Matrix>(out);
+  m_out->mat.create(rows, cols, CV_32F);
+
+  cv::dct(self->mat, m_out->mat, inverse ? 1 : 0);
+
+  info.GetReturnValue().Set(out);
+}
+
 NAN_METHOD(Matrix::AddWeighted) {
   Nan::HandleScope scope;
 

src/Matrix.h

@@ -68,6 +68,7 @@ public:
   JSFUNC(ROI)
   JSFUNC(Ptr)
   JSFUNC(AbsDiff)
+  JSFUNC(Dct)  
   JSFUNC(AddWeighted)
   JSFUNC(BitwiseXor)
   JSFUNC(BitwiseNot)