Notes and guides

Why some tools call a tar file ‘unknown’ and how to tell a POSIX tar from a GNU one.

It is a missing codec, not a broken photo. Three ways to make HEIC display, plus the conversion that keeps 10-bit depth.

Gigapixel panoramas and layered files over 2 GB are written as .psb, and most readers handle both.

‘Create PDF Compatible File’ is the difference between a file a client can look at and a file only Illustrator can read.