How can I download a lossless audio spectrogram?

Question

Python

Good afternoon. I get the spectrogram of an audio file like this:

import librosa
import numpy as np
# write wav file from the amplitude
import soundfile as sf


path = '/content/drive/MyDrive/originalputin/2.mp3.wav'

audio, sr = librosa.load(path)

audio_stft = librosa.stft(audio)

import matplotlib.pyplot as plt
import librosa.display

fig, ax = plt.subplots()
img = librosa.display.specshow(audio_stft, y_axis='log', x_axis='time', ax=ax)
ax.set_title('Spectrogram')
fig.colorbar(img, ax=ax, format="%+2.0f")

At the output, I get something like this picture:



How can I download this picture
1) Without any loss of quality, because shape stft = (1025, 465).
2) Without anything superfluous. Purely this square is colored.

Thank you.