how to convert the spectrogram into an image

using MATLAB, we have converted image into audio (.wav format). Also this audio file is con开发者_StackOverflowverted into spectrogram image. Now we are trying to convert this spectrogram into an original input image

If I understand this correctly, and if the spectrogram was built over non-overlapping "sliding windows", you can then simply do the inverse FFT for each time chunk and combine them to recover the audio signal. Then you perform the inverse of the operation you did to covert image to audio.