For what it's worth, last I checked (Nov 2021) the image was rendered client side. They send a collection of glyphs as SVG strings like "M31.9824,43.9453 L

For what it's worth, last I checked (Nov 2021) the image was rendered client side. They send a collection of glyphs as SVG strings like "M31.9824,43.9453 L364.014,-719.971 L495.117,-719.971 L163.086,43.9453 L31.9824,43.9453 Z " And then each line is a sequence of indices into the glyph array. There isn't a mapping back to letters, that I know of, but one could prepare a table of glyph to character for the fonts they commonly use. That could be used to extract books, but might be a bit complicated/fragile for your use case.