how to extract a single jpg from an ICloud Keynote presentation

With iCloud Keynote, I can't select/copy a single jpg from a presentation or find my original image data anywhere. I don't want to copy a 50 page presentation just to try and extract an image from that pdf or keynote file. I can select the individual image, but it will not allow me to copy it (just delete or move it). I could do this with the computer version of Keynote (a few ways), but not the iCloud. Thanks for your help.