+WIM archives provide data deduplication at the level of full file contents. In
+other words, each unique "file contents" is only stored once in the archive,
+regardless of how many files have that contents across all images.
+
+A WIM archive may be either stand-alone or split into multiple parts.
+
+An update of the WIM format --- first added by Microsoft for Windows 8 ---
+supports solid-mode compression. This refers to files being compressed together
+(e.g. as in a .tar.xz or .7z archive) rather than separately (e.g. as in a .zip
+archive). This usually produces a much better compression ratio. Solid
+archives are sometimes called "ESD files" by Microsoft and may have the ".esd"
+file extension rather than ".wim". They are supported in wimlib since v1.6.0.
+
+ IMAGEX IMPLEMENTATION
+
+wimlib itself is a C library, and it provides a documented public API (See:
+https://wimlib.net/apidoc) for other programs to use. However, it is also
+distributed with a command-line program called "wimlib-imagex" that uses this
+library to implement an imaging tool similar to Microsoft's ImageX.
+wimlib-imagex supports almost all the capabilities of Microsoft's ImageX as well
+as additional capabilities. wimlib-imagex works on both UNIX-like systems and
+Windows, although some features differ between the platforms.
+
+Run `wimlib-imagex' with no arguments to see an overview of the available
+commands and their syntax. For additional documentation:
+
+ * If you have installed wimlib-imagex on a UNIX-like system, you will find
+ further documentation in the man pages; run `man wimlib-imagex' to get
+ started.
+
+ * If you have downloaded the Windows binary distribution, you will find the
+ documentation for wimlib-imagex in PDF format in the "doc" directory,
+ ready for viewing with any PDF viewer. Please note that although the PDF
+ files are converted from UNIX-style "man pages", they do document
+ Windows-specific behavior when appropriate.
+
+ COMPRESSION RATIO
+
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM files.
+wimlib's compression codecs usually outperform and outcompress their Microsoft
+equivalents. Although results will vary depending on the data being compressed,
+the table below shows results for a common use case: creating an x86 Windows PE
+image ("boot.wim"). Each row shows the compression type, the size of the
+resulting WIM file in bytes, and the time it took to create the file. When
+possible, the results with the Microsoft equivalent are included.
+
+ =============================================================================
+ | Compression || wimlib (v1.8.3) | WIMGAPI (Windows 10) |
+ =============================================================================
+ | None [1] || 361,314,224 in 2.7s | 361,315,338 in 3.0s |
+ | XPRESS [2] || 137,954,729 in 3.0s | 140,457,081 in 6.4s |
+ | XPRESS (slow) [3] || 135,147,054 in 8.0s | N/A |
+ | LZX (quick) [4] || 130,098,933 in 3.3s | N/A |
+ | LZX (normal) [5] || 126,310,241 in 9.9s | 127,293,110 in 18.5s |
+ | LZX (slow) [6] || 125,884,919 in 17.4s | N/A |
+ | LZMS (non-solid) [7] || 116,150,698 in 23.4s | N/A |
+ | LZMS (solid) [8] || 88,108,326 in 55.6s | 88,771,800 in 90.9s |
+ | "WIMBoot" [9] || 166,892,801 in 3.0s | 169,108,689 in 8.9s |
+ | "WIMBoot" (slow) [10] || 165,004,333 in 7.8s | N/A |
+ =============================================================================
+
+Notes:
+ [1] '--compress=none' for wimlib-imagex; '/compress:none' for DISM.
+
+ [2] '--compress=XPRESS' for wimlib-imagex; '/compress:fast' for DISM.
+ Compression chunk size defaults to 32768 bytes in both cases.
+
+ [3] '--compress=XPRESS:80' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [4] '--compress=LZX:20' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [5] '--compress=LZX' or '--compress=LZX:50' or no option for wimlib-imagex;
+ '/compress:maximum' for DISM.
+ Compression chunk size defaults to 32768 bytes in both cases.
+
+ [6] '--compress=LZX:100' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 32768 bytes.
+
+ [7] '--compress=LZMS' for wimlib-imagex; no known equivalent for DISM.
+ Compression chunk size defaults to 131072 bytes.
+
+ [8] '--solid' for wimlib-imagex. Should be '/compress:recovery' for DISM,
+ but only works for /Export-Image, not /Capture-Image. Compression chunk
+ size in solid resources defaults to 67108864 bytes in both cases.
+
+ [9] '--wimboot' for wimlib-imagex; '/wimboot' for DISM.
+ This is really XPRESS compression with 4096 byte chunks, so the same as
+ '--compress=XPRESS --chunk-size=4096'.
+
+ [10] '--wimboot --compress=XPRESS:80' for wimlib-imagex;
+ no known equivalent for DISM.
+ Same format as [9], but trying harder to get a good compression ratio.
+
+Note: wimlib-imagex's --compress option also accepts the "fast", "maximum", and
+"recovery" aliases for XPRESS, LZX, and LZMS, respectively.
+
+Testing environment:
+
+ - 64 bit binaries
+ - Windows 10 virtual machine running on Linux with VT-x
+ - 4 CPUs and 4 GiB memory given to virtual machine
+ - SSD-backed virtual disk
+ - All tests done with page cache warmed
+
+The compression ratio provided by wimlib is also competitive with commonly used
+archive formats. Below are file sizes that result when the Canterbury corpus is
+compressed with wimlib (v1.8.3), WIMGAPI (Windows 8.1), and some other
+formats/programs:
+
+ =====================================================
+ | Format | Size (bytes) |
+ =====================================================
+ | tar | 2,826,240 |
+ | WIM (WIMGAPI, None) | 2,814,254 |
+ | WIM (wimlib, None) | 2,814,216 |
+ | WIM (WIMGAPI, XPRESS) | 825,536 |
+ | WIM (wimlib, XPRESS) | 787,356 |
+ | tar.gz (gzip, default) | 738,796 |
+ | ZIP (Info-ZIP, default) | 735,334 |
+ | tar.gz (gzip, -9) | 733,971 |
+ | ZIP (Info-ZIP, -9) | 732,297 |
+ | WIM (wimlib, LZX quick) | 686,420 |
+ | WIM (WIMGAPI, LZX) | 651,866 |
+ | WIM (wimlib, LZX normal) | 623,718 |
+ | WIM (wimlib, LZX slow) | 619,382 |
+ | WIM (wimlib, LZMS non-solid) | 581,046 |
+ | tar.bz2 (bzip, default) | 565,008 |
+ | tar.bz2 (bzip, -9) | 565,008 |
+ | WIM (WIMGAPI, LZMS solid) | 521,366 |
+ | WIM (wimlib, LZMS solid) | 515,800 |
+ | tar.xz (xz, default) | 486,916 |
+ | tar.xz (xz, -9) | 486,904 |
+ | 7z (7-zip, default) | 484,700 |
+ | 7z (7-zip, -9) | 483,239 |
+ =====================================================
+
+Note: WIM does even better on directory trees containing duplicate files, which
+the Canterbury corpus doesn't have.
+
+ NTFS SUPPORT
+
+WIM images may contain data, such as alternate data streams and
+compression/encryption flags, that are best represented on the NTFS filesystem
+used on Windows. Also, WIM images may contain security descriptors which are
+specific to Windows and cannot be represented on other operating systems.
+wimlib handles this NTFS-specific or Windows-specific data in a
+platform-dependent way:
+
+ * In the Windows version of wimlib and wimlib-imagex, NTFS-specific and
+ Windows-specific data are supported natively.
+
+ * In the UNIX version of wimlib and wimlib-imagex, NTFS-specific and
+ Windows-specific data are ordinarily ignored; however, there is also special
+ support for capturing and extracting images directly to/from unmounted NTFS
+ volumes. This was made possible with the help of libntfs-3g from the
+ NTFS-3g project.
+
+For both platforms the code for NTFS capture and extraction is complete enough
+that it is possible to apply an image from the "install.wim" contained in recent
+Windows installation media (Vista or later) directly to an NTFS filesystem, and
+then boot Windows from it after preparing the Boot Configuration Data. In
+addition, a Windows installation can be captured (or backed up) into a WIM file,
+and then re-applied later.
+
+ WINDOWS PE
+
+A major use for wimlib and wimlib-imagex is to create customized images of
+Windows PE, the Windows Preinstallation Environment, on either UNIX-like systems
+or Windows without having to rely on Microsoft's software and its restrictions
+and limitations.
+
+Windows PE is a lightweight version of Windows that can run entirely from memory
+and can be used to install Windows from local media or a network drive or
+perform maintenance. It is the operating system that runs when you boot from
+the Windows installation media.
+
+You can find Windows PE on the installation media for Windows (Vista or later)
+as the file `sources/boot.wim'. Windows PE can also be found in the Windows
+Automated Installation Kit (WAIK), which is free to download from Microsoft,
+inside the `WinPE.cab' file, which you can extract natively on Windows, or on
+UNIX-like systems if you install either the `cabextract' or `p7zip' programs.
+
+In addition, Windows installations and recovery partitions frequently contain a
+WIM containing an image of the Windows Recovery Environment, which is similar to
+Windows PE.
+
+A shell script `mkwinpeimg' is distributed with wimlib on UNIX-like systems to
+ease the process of creating and customizing a bootable Windows PE image.
+
+ DEPENDENCIES
+
+This section documents the dependencies of wimlib and the programs distributed
+with it, when building for a UNIX-like system from source. If you have
+downloaded the Windows binary distribution of wimlib and wimlib-imagex then all
+dependencies were already included and this section is irrelevant.
+
+* libxml2 (required)
+ This is a commonly used free library to read and write XML documents.
+ Almost all Linux distributions should include this; however, you may
+ need to install the header files, which might be in a package named
+ "libxml2-dev" or similar. For more information see http://xmlsoft.org/.
+
+* libfuse (optional but recommended)
+ Unless configured --without-fuse, wimlib requires a non-ancient version
+ of libfuse. Most Linux distributions already include this, but make
+ sure you have the libfuse package installed, and also libfuse-dev if
+ your distribution distributes header files separately. FUSE also
+ requires a kernel module. If the kernel module is available it should
+ automatically be loaded if you try to mount a WIM image. For more
+ information see http://fuse.sourceforge.net/.
+
+* libattr (optional but recommended)
+ Unless configured --without-fuse, wimlib also requires libattr. Almost
+ all Linux distributions should include this; however, you may need to
+ install the header files, which might be in a package named "attr-dev",
+ "libattr1-dev", or similar.
+
+* libntfs-3g (optional but recommended)
+ Unless configured --without-ntfs-3g, wimlib requires the library and
+ headers for libntfs-3g version 2011-4-12 or later to be installed.
+
+* OpenSSL / libcrypto (optional)
+ wimlib can use the SHA-1 message digest implementation from libcrypto
+ (usually provided by OpenSSL) instead of compiling in yet another SHA-1
+ implementation.
+
+* cdrkit (optional)
+* mtools (optional)
+* syslinux (optional)
+* cabextract (optional)
+ The `mkwinpeimg' shell script will look for several other programs
+ depending on what options are given to it. Depending on your Linux
+ distribution, you may already have these programs installed, or they may
+ be in the software repository. Making an ISO filesystem requires
+ `mkisofs' from `cdrkit' (http://www.cdrkit.org). Making a disk image
+ requires `mtools' (http://www.gnu.org/software/mtools) and `syslinux'
+ (http://www.syslinux.org). Retrieving files from the Windows Automated
+ Installation Kit requires `cabextract' (http://www.cabextract.org.uk).
+
+ CONFIGURATION
+
+This section documents the most important options that may be passed to the
+"configure" script when building from source:
+
+--without-ntfs-3g
+ If libntfs-3g is not available or is not version 2011-4-12 or later,
+ wimlib can be built without it, in which case it will not be possible to
+ capture or apply WIM images directly from/to NTFS volumes.
+
+ The default is --with-ntfs-3g when building for any UNIX-like system,
+ and --without-ntfs-3g when building for Windows.