PCX and PCC files are a fairly early PC graphic format, which has been extended over the years to support more and varied color depths. PCX files may or may not be compressed; ThumbsPlus always writes version 5, compressed PCX files, in the color depth of the current image. ThumbsPlus does support 24-bit (3-planes x 8-bits per pixel) PCX files.
Note: The only known PCX format not supported by ThumbsPlus is 2-plane CGM files (4 color). These files may be supported in the future if there is sufficient interest.