In the sample Notebook, there are two blocks of binary data which are preceded by “image/png”, claearly suggesting that they are .png files. I tried to make a file of one of these blocks and it was rejected with the error message “invalid png header”.
I looked this up and it said that bytes 2,3, and 4 spell ‘PNG’ in ascii as a clear identifier. I tried this on a known .png file and this is indeed correct. Yet this is absent in the data in the Notebook. So, how are we to interpret these blocks of data.