300 dpi - 300 dots per inch; the minimum resolution limits for a publishable figure according to my publisher. The problem is that you can find a great many illustrations and images that look just great on a computer screen but are about 75-95 dpi, one-third the required resolution. To increase the resolution you can reduce the size, and suddenly a decent sized image gets really tiny. And when you're looking for very particular botanical images it gets much harder. Not just everyone happens to have an image of a hornwort with sporophytes laying around. And if they do have a good image, one rarely used, why they very reasonably think that it's use can command a pretty good price, which works out very well for both of us except the entire illustration budget for TPP's book is zilch. That's right, zilch, so without the remarkable generosity of colleagues and people who post great images on the Creative Commons, us publishing paupers would be toast. Got a good image of Takakia or Tmesipteris, let TPP know. TPP would mention the program used to generate these images and plates for publication, but it might be mistaken for an endorsement. While a very amazing program in terms of quality of the results, it is without question the most non-intuitive computer program TPP has ever used, and he's used a lot of them.