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Build, their current values, and a help string describing what they do.Installing libjpeg-turboYou can use the build system to install libjpeg-turbo (as opposed to creating an installer package.) To do this, run make install or nmake install (or build the “install” target in the Visual Studio IDE.) Running make uninstall or nmake uninstall (or building the “uninstall” target in the Visual Studio IDE) will uninstall libjpeg-turbo.The CMAKE_INSTALL_PREFIX CMake variable can be modified in order to install libjpeg-turbo into a directory of your choosing. If you don't specify CMAKE_INSTALL_PREFIX, then the default is:c:\libjpeg-turbo Visual Studio 32-bit buildc:\libjpeg-turbo64 Visual Studio 64-bit buildc:\libjpeg-turbo-gcc MinGW 32-bit buildc:\libjpeg-turbo-gcc64 MinGW 64-bit build/opt/libjpeg-turbo Un*xThe default value of CMAKE_INSTALL_PREFIX causes the libjpeg-turbo files to be installed with a directory structure resembling that of the official libjpeg-turbo binary packages. Changing the value of CMAKE_INSTALL_PREFIX (for instance, to /usr/local) causes the libjpeg-turbo files to be installed with a directory structure that conforms to GNU standards.The CMAKE_INSTALL_BINDIR, CMAKE_INSTALL_DATAROOTDIR, CMAKE_INSTALL_DOCDIR, CMAKE_INSTALL_INCLUDEDIR, CMAKE_INSTALL_JAVADIR, CMAKE_INSTALL_LIBDIR, and CMAKE_INSTALL_MANDIR CMake variables allow a finer degree of control over where specific files in the libjpeg-turbo distribution should be installed. These directory variables can either be specified as absolute paths or as paths relative to CMAKE_INSTALL_PREFIX (for instance, setting CMAKE_INSTALL_DOCDIR to doc would cause the documentation to be installed in ${CMAKE_INSTALL_PREFIX}/doc.) If a directory variable contains the name of another directory variable in angle brackets, then its final value will depend on the final value of that other variable. For instance, the default value of CMAKE_INSTALL_MANDIR is /man.Creating Distribution PackagesThe following commands can be used to create various types of distribution packages:Linuxmake rpmCreate Red Hat-style binary RPM package. Requires RPM v4 or later.make srpmThis runs make dist to create a pristine source tarball, then creates a Red Hat-style source RPM package from the tarball. Requires RPM v4 or

Later.make debCreate Debian-style binary package. Requires dpkg.Macmake dmgCreate Mac package/disk image. This requires pkgbuild and productbuild, which are installed by default on OS X/macOS 10.7 and later.In order to create a Mac package/disk image that contains universal x86-64/Arm binaries, set the following CMake variable:SECONDARY_BUILD: Directory containing a cross-compiled x86-64 or Armv8 (64-bit) iOS or macOS build of libjpeg-turbo to include in the universal binariesYou should first use CMake to configure the cross-compiled x86-64 or Armv8 secondary build of libjpeg-turbo (see “Building libjpeg-turbo for iOS” above, if applicable) in a build directory that matches the one specified in the aforementioned CMake variable. Next, configure the primary (native) build of libjpeg-turbo as an out-of-tree build, specifying the aforementioned CMake variable, and build it. Once the primary build has been built, run make dmg from the build directory. The packaging system will build the secondary build, use lipo to combine it with the primary build into a single set of universal binaries, then package the universal binaries.WindowsIf using NMake:cd {build_directory}nmake installerIf using MinGW:cd {build_directory}make installerIf using the Visual Studio IDE, build the “installer” target.The installer package (libjpeg-turbo-{version}[-gcc|-vc][64].exe) will be located under {build_directory}. If building using the Visual Studio IDE, then the installer package will be located in a subdirectory with the same name as the configuration you built (such as {build_directory}\Debug\ or {build_directory}\Release).Building a Windows installer requires the Nullsoft Install System. makensis.exe should be in your PATH.Regression testingThe most common way to test libjpeg-turbo is by invoking make test (Un*x) or nmake test (Windows command line) or by building the “RUN_TESTS” target (Visual Studio IDE), once the build has completed. This runs a series of tests to ensure that mathematical compatibility has been maintained between libjpeg-turbo and libjpeg v6b. This also invokes the TurboJPEG unit tests, which ensure that the colorspace extensions, YUV

(usually /usr/bin.) Next, execute the following commands:cd {build_directory}cmake -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake \ -DCMAKE_INSTALL_PREFIX={install_path} \ [additional CMake flags] {source_directory}make{install_path} is the path under which the libjpeg-turbo binaries should be installed.64-bit MinGW Build on Un*x (including Mac and Cygwin)Create a file called toolchain.cmake under {build_directory}, with the following contents:set(CMAKE_SYSTEM_NAME Windows)set(CMAKE_SYSTEM_PROCESSOR AMD64)set(CMAKE_C_COMPILER {mingw_binary_path}/x86_64-w64-mingw32-gcc)set(CMAKE_RC_COMPILER {mingw_binary_path}/x86_64-w64-mingw32-windres){mingw_binary_path} is the directory under which the MinGW binaries are located (usually /usr/bin.) Next, execute the following commands:cd {build_directory}cmake -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake \ -DCMAKE_INSTALL_PREFIX={install_path} \ [additional CMake flags] {source_directory}make{install_path} is the path under which the libjpeg-turbo binaries should be installed.Building libjpeg-turbo for iOSiOS platforms, such as the iPhone and iPad, use Arm processors, and all currently supported models include Neon instructions. Thus, they can take advantage of libjpeg-turbo's SIMD extensions to significantly accelerate JPEG compression/decompression. This section describes how to build libjpeg-turbo for these platforms.Armv8 (64-bit)Xcode 5 or later required, Xcode 6.3.x or later recommendedThe following script demonstrates how to build libjpeg-turbo to run on the iPhone 5S/iPad Mini 2/iPad Air and newer.IOS_PLATFORMDIR=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platformIOS_SYSROOT=($IOS_PLATFORMDIR/Developer/SDKs/iPhoneOS*.sdk)export CFLAGS="-Wall -miphoneos-version-min=8.0 -funwind-tables"cd {build_directory}cmake -G"Unix Makefiles" \ -DCMAKE_C_COMPILER=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang \ -DCMAKE_OSX_ARCHITECTURES=arm64 \ -DCMAKE_OSX_SYSROOT=${IOS_SYSROOT[0]} \ [additional CMake flags] {source_directory}makeReplace iPhoneOS with iPhoneSimulator and -miphoneos-version-min with -miphonesimulator-version-min to build libjpeg-turbo for the iOS simulator on Macs with Apple silicon CPUs.Building libjpeg-turbo for AndroidBuilding libjpeg-turbo for Android platforms requires v13b or later of the Android NDK.Armv7 (32-bit)NDK r19 or later with Clang recommendedThe following is a general recipe script that can be modified for your specific needs.# Set these variables to suit your needsNDK_PATH={full path to the NDK directory-- for example, /opt/android/android-ndk-r16b}TOOLCHAIN={"gcc" or "clang"-- "gcc" must be used with NDK r16b and earlier, and "clang" must be used with NDK r17c and later}ANDROID_VERSION={the minimum version of Android to support-- for example, "16", "19", etc.}cd {build_directory}cmake -G"Unix Makefiles" \ -DANDROID_ABI=armeabi-v7a \ -DANDROID_ARM_MODE=arm \ -DANDROID_PLATFORM=android-${ANDROID_VERSION} \ -DANDROID_TOOLCHAIN=${TOOLCHAIN} \ -DCMAKE_ASM_FLAGS="--target=arm-linux-androideabi${ANDROID_VERSION}" \ -DCMAKE_TOOLCHAIN_FILE=${NDK_PATH}/build/cmake/android.toolchain.cmake \ [additional

For 32-bit and 64-bit builds.You can then open ALL_BUILD.vcproj in Visual Studio and build one of the configurations in that project (“Debug”, “Release”, etc.) to generate a full build of libjpeg-turbo.This will generate the following files under {build_directory}:{configuration}/jpeg-static.lib Static link library for the libjpeg API{configuration}/jpeg{version}.dll DLL for the libjpeg API{configuration}/jpeg.lib Import library for the libjpeg API{configuration}/turbojpeg-static.lib Static link library for the TurboJPEG API{configuration}/turbojpeg.dll DLL for the TurboJPEG API{configuration}/turbojpeg.lib Import library for the TurboJPEG API{configuration} is Debug, Release, RelWithDebInfo, or MinSizeRel, depending on the configuration you built in the IDE, and {version} is 62, 7, or 8, depending on whether libjpeg v6b (default), v7, or v8 emulation is enabled.MinGWNOTE: This assumes that you are building on a Windows machine using the MSYS environment. If you are cross-compiling on a Un*x platform (including Mac and Cygwin), then see “Build Recipes” below.cd {build_directory}cmake -G"MSYS Makefiles" [additional CMake flags] {source_directory}makeThis will generate the following files under {build_directory}:libjpeg.a Static link library for the libjpeg APIlibjpeg-{version}.dll DLL for the libjpeg APIlibjpeg.dll.a Import library for the libjpeg APIlibturbojpeg.a Static link library for the TurboJPEG APIlibturbojpeg.dll DLL for the TurboJPEG APIlibturbojpeg.dll.a Import library for the TurboJPEG API{version} is 62, 7, or 8, depending on whether libjpeg v6b (default), v7, or v8 emulation is enabled.Debug BuildAdd -DCMAKE_BUILD_TYPE=Debug to the CMake command line. Or, if building with NMake, remove -DCMAKE_BUILD_TYPE=Release (Debug builds are the default with NMake.)libjpeg v7 or v8 API/ABI EmulationAdd -DWITH_JPEG7=1 to the CMake command line to build a version of libjpeg-turbo that is API/ABI-compatible with libjpeg v7. Add -DWITH_JPEG8=1 to the CMake command line to build a version of libjpeg-turbo that is API/ABI-compatible with libjpeg v8. See README.md for more information about libjpeg v7 and v8 emulation.Arithmetic Coding SupportSince the patent on arithmetic coding has expired, this functionality has been included in this release of libjpeg-turbo. libjpeg-turbo's

Operating systems, maintained by an informal independent group and iterating occasionally. It tries to balance encoding speed, quality, and file size. Libjpeg-turbo is intended to be a higher performance replacement for libjpeg, and it is in fact the default library for most Linux distributions. “Performance” in this scenario means using less CPU time during encoding and decoding. Libjpeg-turbo forked libjpeg in 2010 and claims to be “generally 2-6x as fast as libjpeg, all else being equal.” MozJPEG is intended for a specific use case: images on the web. Mozilla forked libjpeg-turbo in 2014 so they could focus on reducing file size in order to reduce bandwidth and get images on the web to load faster. It does this through progressive coding and trellis quantization that sacrifices some encoding time, in the range of 4-7x. You can read the libjpeg-turbo creator’s thoughts on MozJPEG and why their two projects’ goals are incompatible. Guetzli is what brings us here today, and it is focused on image quality. Google uses a new perceptual psychovisual model to decide where image quality loss will be the least noticeable. It sacrifices encoding time, on the order of 800-1000x slower than MozJPEG. Google claims file byte size is about 20-30% smaller than libjpeg, which is comparable to MozJPEG. Google Guetzli vs MozJPEG Head-to-Head Comparison Test Computer Overview MacBook Air (13-inch, Early 2015) Processor: 1.6 GHz Intel Core i5 Memory: 4 GB 1600 MHz DDR3 Encoders Mozilla MozJPEG Google Guetzli Methodology I’m going to export product images from Photoshop as quality 100 JPG and then run each through both MozJPEG and Guetzli at quality 90. I’ll give before-and-after images for quality comparison, record CPU encoding time, and compare file sizes. Commands: $ time mozcjpeg -quality 90 -progressive [input] > [output] $ time guetzli --quality 90 [input] [output] I’ll