INTRODUCTION
-This is wimlib version 1.5.1 (October 2013). wimlib is a C library for creating,
+This is wimlib version 1.5.2 (November 2013). wimlib is a C library for creating,
modifying, extracting, and mounting files in the Windows Imaging Format (WIM
files). These files are normally created by using the `imagex.exe' utility on
Windows, but wimlib is distributed with a free implementation of ImageX called
Windows filesystems. However, it can be used on other platforms as well, with
some limitations. Like some other archive formats such as ZIP, files in WIM
archives may be compressed. WIM files support two compression formats: LZX and
-XPRESS. Both are supported by wimlib.
+XPRESS *. Both are supported by wimlib.
A WIM file consists of one or more "images". Each image is an independent
top-level directory structure and is logically separate from all other images in
A WIM file may be either stand-alone or split into multiple parts. Split WIMs
are read-only and cannot be modified.
+* Note: The Windows 8 WIMGAPI apparently adds a third format, LZMS, but it is
+ not documented and is incompatible with ImageX and Dism. It is unclear if
+ this new format is actually being used for anything.
+
IMAGEX IMPLEMENTATION
wimlib itself is a C library, and it provides a documented public API (See:
wimlib (and wimlib-imagex) can create XPRESS or LZX compressed WIM archives.
Currently, the XPRESS compression ratio is slightly better than that provided by
-Microsoft's software, while the LZX compression ratio is approaching that of
-Microsoft's software but is not quite there yet. Running time is as good as or
-better than Microsoft's software, especially with multithreaded compression,
-available in wimlib v1.1.0 and later.
+Microsoft's software, while by default the LZX compression ratio is approaching
+that of Microsoft's software but is not quite there yet. Running time is as
+good as or better than Microsoft's software, especially with multithreaded
+compression, available in wimlib v1.1.0 and later.
The following tables compare the compression ratio and performance for creating
a compressed x86_64 Windows PE image. Note: these timings were done on Windows
wimlib-imagex (v1.4.0, 2 threads): 18 sec 51 sec
Microsoft imagex.exe: 25 sec 93 sec
+The above LZX values are using the default LZX compressor. wimlib v1.5.2
+introduced a new experimental LZX compressor which can be enabled by passing
+'--compress-slow' to `wimlib-imagex capture' or `wimlib-imagex optimize'. This
+compressor is much slower but compresses the data slightly more --- currently
+usually to within a fraction of a percent of the results from imagex.exe.
+
NTFS SUPPORT
WIM images may contain data, such as alternate data streams and