On 9/7/19 7:36 AM, Stefan Monnier wrote:
> is there
> a good reason to bzip-compress a .png file?

Although typically bzip2 doesn't compress .png files well, there are 
counterexamples such as the attached contrived file which has an 878:1 
compression ratio.

PS. Watch out, it's a torture-test image. If you uncompress it and view it, 
older versions of Emacs will crash and newer versions show only a placeholder 
box, ImagickMagick's "display" program dumps core, Firefox displays it only at 
lower resolution while chewing up CPU, etc.)