idwt() missing 1 required positional argument: 'wavelet'

The error message you are encountering suggests that the `idwt()` function is missing a required argument called 'wavelet'. In wavelet-based image processing, the 'wavelet' refers to the specific wavelet function or filter bank used for decomposition and reconstruction.

To resolve this issue, you need to provide the 'wavelet' argument when calling the `idwt()` function. This argument should be a valid wavelet name or filter bank object depending on the library or package you are using for wavelet transformations.

For example, if you are using the PyWavelets library in Python, you can choose a wavelet function from their available options and pass it as the 'wavelet' argument. Here's an example:

import pywt

# Assuming you have a signal called 'signal' and coefficients 'cA' and 'cD'
reconstructed_signal = pywt.idwt(cA, cD, wavelet='db4')

Make sure to replace `'db4'` with the desired wavelet name for your specific application.