Originally Posted by kovidgoyal
Try using the TamperData firefox extension to see exactly what happens when you fetch with a browser.
I've looked with Live HTTP Headers, but since I'm not sure what's happening with Calibre, it's hard to spot a difference. I suppose I could set up a packet sniffer, but that's a bit more effort than I want to expend. Alternatively, I may just use wget to see whether it pulls the same images that the browser pulls or the images that Calibre gets. That may give me a clue.