Myst PICT resources
PICT resources contain the main game graphics in Myst Masterpiece Edition, replacing most WDIBs of the original edition with true-color versions.
They contain pictures stored in plain Apple PICT format. They start with the usual 512 byte block of platform-dependent data as in regular MacOS PICT resources. JPEG contents have been observed and correctly decoded; the JPEG block starts at offset 726 and can be simply extracted and decoded.
Note however that a few perverse PICT resources just retain the WDIB format (e.g. IDs 2105 and 2112 from the Stoneship archive).