public void InverseT(UMat reIn, UMat imIn, UMat magOut, UMat phOut)
{
///accepts real and imaginary parts, inverse (fourier) Transforms
///converts real and imaginary output parts to magnitude and
///phase, returns magnitude and phase parts.
///Refer to ForwardT() for more info on why I code like this.
///Reference: https://stackoverflow.com/questions/16812950/how-do-i-compute-dft-and-its-reverse-with-emgu
VectorOfUMat vec = this.vec;
vec.Push(reIn);
vec.Push(imIn);
UMat cImg = this.img32f2c;
CvInvoke.Merge(vec, cImg); //because Dft method accepts and outputs 2-channel image
CvInvoke.Dft(cImg, cImg, DxtType.Inverse, 0);
//new objects put into vec, vec[0] is reOut, vec[1] is imOut.
CvInvoke.Split(cImg, vec);
//convert output of inverse Transform to magnitude and polar
CvInvoke.CartToPolar(vec[0], vec[1], magOut, phOut);
vec.Clear();
}
public void ProcessForwardT(UMat inImg, UMat outMagT, UMat outPhT, bool zeroPad = false, bool switchQuadrants = true)
{
///Accepts a 1-channel image, updates outMagT and outPhT.
///magnitude and phase, cause I can't think of why you
///would wanna look at real and imaginary Transforms.
///Also can't think of how you can get complex-valued images.
///Quadrant rearranging doesn't support odd rows or cols.
///T stuff, reference: https://docs.opencv.org/master/d8/d01/tutorial_discrete_fourier_transform.html
//convert image to 32bit float because spacial frequency
//domain values are way bigger than spatial domain values.
UMat re = outMagT; //32-bit float real image, use memory from
//outMagT cause it's gonna be updated anyway
inImg.ConvertTo(re, DepthType.Cv32F);
if (zeroPad)
{
//zero pad for faster dft
ZeroPadImage(re);
}
//create imaginary image of zeros of same depthType
//and size as image representing real plane
UMat im = outPhT; //imaginary
im.Create(re.Rows, re.Cols, re.Depth, re.NumberOfChannels); //allocate memory so you can set it to zero array
//if memory hasn't already been allocated for it
im.SetTo(new MCvScalar(0));
/// Quick exerpt about VectorOfUMat:
/// if you create a VectorOfUMat vec, only if the first UMat variable
/// to store the object is the vector node, like
/// VectorOfUMat vec = new VectorOfUmat(new Umat(), new Umat());
/// vec.Push(someUMat.Clone());
/// then vec.Dispose/Clear actually disposes all the objects referenced
/// to by the UMats in vec. In this case, if you did:
/// VectorOfUMat vec = new VectorOfUMat(inImg.Clone(), inImg.Clone());
/// UMat one = vec[0];
/// one.Dispose();
/// one.Dispose actually does nothing.
/// Otherwise, if
/// UMat one = new UMat();
/// UMat two = new UMat();
/// VectorOfUMat vec = new VectorOfUmat(one);
/// vec.Push(two);
/// calling vec.Dispose() doesn't dispose the objects.
/// you have to call one.Dispose and two.Dispose.
/// Note: no matter whether the UMat's first variable stored
/// in is in a vector node or not, calling vec[index].Dispose
/// does NOTHING.
/// The situation is the same for vec.Clear, except Clear doesn't
/// dispose of vec itself, it just disposes the objects the UMats in
/// it reference to.
//Dft accepts 2-channel images, so we use Merge to merge
//our 2 1-channel images into a single 2-channel image.
//Merge accepts object arrays, so we create a VectorOfUMat
//of our 2 images to feed into Merge.
VectorOfUMat vec = this.vec;
UMat cImg = this.img32f2c;
vec.Push(re);
vec.Push(im); //vec[0] = re, vec[1] = im
;
CvInvoke.Merge(vec, cImg);
CvInvoke.Dft(cImg, cImg, DxtType.Forward, 0); //use back the same memory
//switch quadrants while images are still combined
if (switchQuadrants)
{
SwitchQuadrants(cImg);
}
//make the 2-channel array into 2 1-channel arrays
CvInvoke.Split(cImg, vec); //vec[0] is reT, vec[1] is imT, they are new objects.
CvInvoke.CartToPolar(vec[0], vec[1], outMagT, outPhT);
vec.Clear(); //dispose reT and imT.TODO: find a way to get rid of allocating memory for reT and imT.
}