Booty and the Beasts is a 1979 monster and treasure book from Fantasy Art Enterptises. Art by Erol Otus, text by Otus, Mathias Genser, and Paul Reiche III, A pdf of this book has been floating around for a decade or more. As you can see from the dude on the front cover, some of the stuff in it leans more sci-fi than fantasy.
For a while I wanted to see what a color version of this flag would look like.
I'm just guessing at the colors here. Some combination of red, white, and blue seems like a no brainer. The texturing used by Otus suggests a non-white color for the small stars. The central star lacks that texture, suggesting a different hue. I went with yellow since ol' Sol is a yellow star. Here's an alternative take:
Here's another take that less resembles the flag used by Japan in WWII. Not sure which I prefer. Anybody got any other ideas?