Not sure if there are official IA specs for such things but pretty much all of these old magazine scans tend to have a ZIP full of JPEG2000 images, which the IA will generate directory listings for:

https://archive.org/download/Forth_Dimension_Volume_06_Numbe...

From there you can hit those 'jpg' links next to each page, though the URLs can get pretty long:

https://archive.org/download/Forth_Dimension_Volume_06_Numbe...

https://archive.org/download/Forth_Dimension_Volume_06_Numbe...