The PICT format is the Macintosh's native drawing format (similar to WMF on Windows). ThumbsPlus supports version 1, version 2 and version 2 extended formats. Vector (drawing) commands are handled as well as images. When ThumbsPlus recognizes that a PICT file has only raster information, the file is loaded as a bitmap; otherwise, it is loaded as a metafile.
There are some commands in PICT files that are not handled, or not supported completely. We will continue to improve support for PICT over the next few releases.