Q. C++でdouble型の配列をHALCONに渡してFFTするサンプルはありますでしょうか？
A. 下記のサンプルをご参照ください

#include <windows.h>
#include <stdio.h>
#include <halconcpp.h>

using namespace HalconCpp;

int main()
{
	HObject  ho_Image, ho_ImageFFT, ho_CircleOut;
	HObject  ho_CircleIn, ho_BandpassArea, ho_ImageReduced, ho_ZeroFillArea;
	HObject  ho_ImageFFTFiltered, ho_ImageFiltered;
	HTuple  hv_Width, hv_Height, hv_Grayval;

	constexpr size_t size = 100;
	HTuple WindowHandle;
	OpenWindow(0, 0, HTuple(int(size)), HTuple(int(size)), 0, "visible", "", &WindowHandle);
	double buf[size][size]{ 0 };
	GenImageConst(&ho_Image, "real", 100, 100);
	for (size_t i = 0; i < size; i++)
	{
		for (size_t j = 0; j < size; j++)
		{
			buf[i][j] = 655.35 * (i + j) - 65535.1;
			SetGrayval(ho_Image, HTuple(int(i)), HTuple(int(j)), buf[i][j]);
		}
	}

	DispObj(ho_Image, WindowHandle);
	WriteImage(ho_Image, "tiff", 0, "./input");
	WaitSeconds(5.0);
	FftGeneric(ho_Image, &ho_ImageFFT, "to_freq", -1, "sqrt", "dc_center", "complex");
	//Sample Filter(ref. remove_texture_fft.hdev)
	GetImageSize(ho_ImageFFT, &hv_Width, &hv_Height);
	GenCircle(&ho_CircleOut, hv_Width / 2, hv_Height / 2, ((hv_Width.TupleConcat(hv_Height)).TupleMin()) / 4);
	GenCircle(&ho_CircleIn, hv_Width / 2, hv_Height / 2, ((hv_Width.TupleConcat(hv_Height)).TupleMin()) / 6);
	Difference(ho_CircleOut, ho_CircleIn, &ho_BandpassArea);
	ReduceDomain(ho_ImageFFT, ho_BandpassArea, &ho_ImageReduced);
	Complement(ho_BandpassArea, &ho_ZeroFillArea);
	PaintRegion(ho_ZeroFillArea, ho_ImageReduced, &ho_ImageFFTFiltered, 0, "fill");
	//
	FftGeneric(ho_ImageFFTFiltered, &ho_ImageFiltered, "from_freq", 1, "sqrt", "dc_center", "real");
	DispObj(ho_ImageFiltered, WindowHandle);
	WriteImage(ho_ImageFiltered, "tiff", 0, "./output");

	for (size_t i = 0; i < size; i++)
	{
		for (size_t j = 0; j < size; j++)
		{
			GetGrayval(ho_ImageFiltered, HTuple(int(i)), HTuple(int(j)), &hv_Grayval);
			buf[i][j] = hv_Grayval;
		}
	}
	WaitSeconds(5.0);

	return 0;
}