fft() failed: “index -2 is out of bounds for axis 0 with size 1”
timiil opened this issue · 9 comments
test.csproj:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net7.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Emgu.CV" Version="4.6.0.5131" />
<PackageReference Include="Emgu.CV.runtime.windows" Version="4.6.0.5131" />
<PackageReference Include="Numpy" Version="3.11.1.33" />
</ItemGroup>
</Project>
Program.cs:
using Emgu.CV;
using Emgu.CV.Structure;
using Numpy;
Image<Gray, byte> img = new Image<Gray, byte>(args[0]);
var data = img.Mat.GetRawData();
var ndasrc = np.asfarray(data);
var ndaFFT = np.fft.fft2(ndasrc); //failed here ->
Console.WriteLine(ndaFFT.len);
dotnet run ..\green.tif
failed:
Could not find platform dependent libraries <exec_prefix>
Unhandled exception. Python.Runtime.PythonException: index -2 is out of bounds for axis 0 with size 1
File "C:\Users\timiil\AppData\Local\python-3.11.0-embed-amd64\Lib\numpy\core\fromnumeric.py", line 43, in _wrapit
result = getattr(asarray(obj), method)(*args, **kwds)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\timiil\AppData\Local\python-3.11.0-embed-amd64\Lib\numpy\core\fromnumeric.py", line 54, in _wrapfunc
return _wrapit(obj, method, *args, **kwds)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\timiil\AppData\Local\python-3.11.0-embed-amd64\Lib\numpy\core\fromnumeric.py", line 190, in take
return _wrapfunc(a, 'take', indices, axis=axis, out=out, mode=mode)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "<__array_function__ internals>", line 180, in take
File "C:\Users\timiil\AppData\Local\python-3.11.0-embed-amd64\Lib\numpy\fft\_pocketfft.py", line 688, in _cook_nd_args
s = take(a.shape, axes)
^^^^^^^^^^^^^^^^^^^
File "C:\Users\timiil\AppData\Local\python-3.11.0-embed-amd64\Lib\numpy\fft\_pocketfft.py", line 703, in _raw_fftnd
s, axes = _cook_nd_args(a, s, axes)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\timiil\AppData\Local\python-3.11.0-embed-amd64\Lib\numpy\fft\_pocketfft.py", line 1014, in fft2
return _raw_fftnd(a, s, axes, fft, norm)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "<__array_function__ internals>", line 180, in fft2
at Python.Runtime.PythonException.ThrowLastAsClrException()
at Python.Runtime.PyObject.Invoke(PyTuple args, PyDict kw)
at Python.Runtime.PyObject.InvokeMethod(String name, PyTuple args, PyDict kw)
at Numpy.np.fft.fft2(NDarray a, Int32[] s, Int32[] axes, String norm)
at Program.<Main>$(String[] args) in D:\code\bandpass\app\bandpassdemo\Program.cs:line 13
Can you make a little snippet that doesn't depend on anything else? Show that it works in Python and that it fails in Numpy.NET. Then I can fix the problem quickly.
And no huge data like images please.
test.py:
import cv2
import numpy as np
img = cv2.imread("green.tif", cv2.IMREAD_GRAYSCALE)
fft_img = np.fft.fft2(img)
fft_img = np.fft.fftshift(fft_img)
print(fft_img.size)
python3 ./test.py
the above code is very work. any kind of image like tif or png is OK .
I have here a snippet without cv2 that works in python:
>>> img = np.arange(27).reshape(3,3,3)
>>> img
array([[[ 0, 1, 2],
[ 3, 4, 5],
[ 6, 7, 8]],
[[ 9, 10, 11],
[12, 13, 14],
[15, 16, 17]],
[[18, 19, 20],
[21, 22, 23],
[24, 25, 26]]])
>>> fft_img = np.fft.fft2(img)
>>> fft_img = np.fft.fftshift(fft_img)
>>> fft_img
array([[[ 0. +0.j , -13.5-7.79422863j, 0. +0.j ],
[ -4.5-2.59807621j, 198. +0.j , -4.5+2.59807621j],
[ 0. +0.j , -13.5+7.79422863j, 0. +0.j ]],
[[ 0. +0.j , -13.5-7.79422863j, 0. +0.j ],
[ -4.5-2.59807621j, 36. +0.j , -4.5+2.59807621j],
[ 0. +0.j , -13.5+7.79422863j, 0. +0.j ]],
[[ 0. +0.j , -13.5-7.79422863j, 0. +0.j ],
[ -4.5-2.59807621j, 117. +0.j , -4.5+2.59807621j],
[ 0. +0.j , -13.5+7.79422863j, 0. +0.j ]]])
>>>It also works in C# with Numpy.NET
[TestMethod]
public async Task IssueByTimiil()
{
var img = np.arange(27).reshape(3, 3, 3);
var fft_img = np.fft.fft2(img);
fft_img = np.fft.fftshift(fft_img);
Console.WriteLine(fft_img.repr);
}So my conclusion is that the data you input is wrong. I guess the shape is wrong because I get the same error in python when I apply fft2 to a one-dimensional array.
opencv load an image into an struct Image<Gray, byte> , which should be a 'two dimensional matrix', do i need to convert 'Image<Gray, byte>' or 'Mat' into a one-dimensional array to join fftshift method ??
Image<Gray, byte> img = new Image<Gray, byte>(args[0]);
var data = img.Mat.GetRawData();
var ndasrc = np.asfarray(data);
var ndaFFT = np.fft.fft2(ndasrc); //failed here ->
By doing a GetRawData you get a 1D array and you create a 1D arra ndasrc from it. I guess you need to reshape it so that it has the dimensions of the image.
To be clear you need to do this:
var data = img.Mat.GetRawData();
var ndasrc = np.asfarray(data).reshape(imagew, imageh); before doing the fft2
To be clear you need to do this:
var data = img.Mat.GetRawData(); var ndasrc = np.asfarray(data).reshape(imagew, imageh);before doing the fft2
thanks very much, it is all WORK for now:
var file = args.Length > 0 ? args[0] : @"..\..\..\..\green.tif";
Image<Gray, byte> img = new Image<Gray, byte>(file);
var data = img.Mat.GetRawData();
var ndasrc = np.asfarray(data);
var reshape = ndasrc.reshape(img.Height, img.Width);
var ndaFFT = np.fft.fft2(reshape);
var fftShift = np.fft.fftshift(ndaFFT);
...
Thanks you very much.
BTW, hou can i convert the NDArray back to CLR types ?
var file = args.Length > 0 ? args[0] : @"..\..\..\..\green.tif";
Image<Gray, byte> img = new Image<Gray, byte>(file);
var data = img.Mat.GetRawData();
var ndasrc = np.asfarray(data);
var reshape = ndasrc.reshape(img.Height, img.Width);
byte[,] backraw = null; //which API can make reshape convert (boxing) back to backraw ??
Getting the data of an NDarray as a C# array is documented here: https://github.com/SciSharp/Numpy.NET#create-a-numpy-array-from-a-c-array-and-vice-versa