Here is a list of all documented files with brief descriptions:

libjasper
bmp
bmp_cod.h
bmp_enc.h
include
jasper
jas_cm.h	JasPer Color Management
jas_compiler.h	Compiler-related macros
jas_debug.h	JasPer Debugging-Related Functionality
jas_dll.h	Shared Library Macros
jas_fix.h	JasPer Fixed-Point Number Class
jas_getopt.h	Command Line Option Parsing Code
jas_icc.h	ICC Profile
jas_image.h	JasPer Image Class
jas_init.h	JasPer Initialization/Cleanup Code
jas_log.h	JasPer Logging Functionality
jas_malloc.h	JasPer Memory Allocator
jas_math.h	Math-Related Code
jas_seq.h	Sequence/Matrix Library
jas_stream.h	I/O Stream Class
jas_string.h	String Library
jas_thread.h	Threads
jas_tmr.h	Timer Code
jas_tvp.h	Tag/Value Pair Parser
jas_types.h	Primitive Types
jas_version.h	JasPer Version
jasper.h	JasPer Main Header
jp2
jp2_cod.h
jp2_dec.h
jpc
jpc_bs.h
jpc_cod.h
jpc_cs.h
jpc_dec.h
jpc_enc.h
jpc_fix.h
jpc_flt.h
jpc_math.h
jpc_mct.h
jpc_mqcod.h
jpc_mqdec.h
jpc_mqenc.h
jpc_qmfb.h
jpc_t1cod.h
jpc_t1dec.h
jpc_t1enc.h
jpc_t2cod.h
jpc_t2dec.h
jpc_t2enc.h
jpc_tagtree.h
jpc_tsfb.h
jpc_util.h
jpg
jpg_cod.h
jpg_enc.h
jpg_jpeglib.h
mif
mif_cod.h
pgx
pgx_cod.h
pgx_enc.h
pnm
pnm_cod.h
pnm_enc.h
ras
ras_cod.h
ras_enc.h