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.
The data is usually stored in plain Apple PICT format. It starts with the usual 512 byte block of platform-dependent data as in regular MacOS PICT resources. The PICT opcodes are usually a bunch of utility ones (e.g. PnSize and DefHilite) together with a CompressedQuickTime one containing JPEG data. The JPEG block seems to always start at offset 726 into the resource and can thus be simply extracted and decoded, ignoring the complicated PICT format.
However, a few PICT resources contain more complex PICT data, also including LongComment opcodes. Pixels are given by a DirectBitsRect opcode and they are compressed using a run-length encoding similar to PackBits (packType = 4 in the PixMap). You spot these cases immediately from their large size with respect to JPEG ones. Among these exceptions there are PICT 2258 from STONE.DAT, PICTs 4109, 4112, 4113, 4447, 4461, 4462, 4479-4483, 4551, 4779, 11221, 11222 from MYST.DAT.
Finally, a few perverse PICT resources just retain the WDIB format. Examples are PICTs 2105 and 2112 from STONE.DAT. Fortunately, it is quite easy to discriminate between WDIB and Apple PICT data.