Add the following lines to /etc/magic:
# Paint Shop Pro Image File Format
# (as per specification from JASC Software http://www.jasc.com/)
0 string Paint\ Shop\ Pro\ Image\ File Paint Shop Pro Image
# Version information
>32 leshort x (version %u.
>34 leshort x %u)
# Size as: width x height x bitsperpixel
>50 lelong x %ld
>54 lelong x x %ld
>69 leshort x x %d,
# Number of layers
>86 leshort =1 1 layer
>86 leshort >1 %d layers
# Compression
>67 leshort =0 uncompressed
>67 leshort =1 RLE
>67 leshort =2 LZ77