The figure is a single bitplane animation overlayed in extra half bright (EHB) mode to create this shadow silhouette effect.
Despite only having 16 colors in Hires Rico was able to add more colors by switching the blue colors to cyan halfway down the image, creating an image with a total of 23 colors.
While not personally signed, I did find Rico's name in the "thanks" section of the AMOS manual. Since this also looks very much like his style it should be safe to attribute it to him.
This images uses such a large overscan size that the normal Amiga can't even display complete image.
Used in UGA Newsflash #3 diskmag
Used in UGA Newsflash #4 diskmag