libvips/README.md

# libvips : an image processing library

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# Introduction

libvips is a [demand-driven, horizontally
threaded](https://github.com/libvips/libvips/wiki/Why-is-libvips-quick)
image processing library. Compared to similar
libraries, [libvips runs quickly and uses little
memory](https://github.com/libvips/libvips/wiki/Speed-and-memory-use).
libvips is licensed under the [LGPL
2.1+](https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html).

It has around [300
operations](http://libvips.github.io/libvips/API/current/func-list.html)
covering arithmetic, histograms, convolution, morphological
operations, frequency filtering, colour, resampling,
statistics and others. It supports a large range of [numeric
types](http://libvips.github.io/libvips/API/current/VipsImage.html#VipsBandFormat),
from 8-bit int to 128-bit complex. Images can have any number of bands.
It supports a good range of image formats, including JPEG, TIFF, PNG,
WebP, HEIC, FITS, Matlab, OpenEXR, PDF, SVG, HDR, PPM / PGM / PFM, CSV,
GIF, Analyze, NIfTI, DeepZoom, and OpenSlide. It can also load images via
ImageMagick or GraphicsMagick, letting it work with formats like DICOM.

It comes with bindings for
[C](http://libvips.github.io/libvips/API/current/using-from-c.html),
[C++](http://libvips.github.io/libvips/API/current/using-from-cpp.html),
and the
[command-line](http://libvips.github.io/libvips/API/current/using-cli.html).
Full bindings are available for [Ruby](https://rubygems.org/gems/ruby-vips),
[Python](https://pypi.python.org/pypi/pyvips),
[PHP](https://github.com/libvips/php-vips),
[C# / .NET](https://www.nuget.org/packages/NetVips),
[Go](https://github.com/davidbyttow/govips), and
[Lua](https://github.com/libvips/lua-vips). libvips
is used as an image processing engine by [sharp
(on node.js)](https://www.npmjs.org/package/sharp),
[bimg](https://github.com/h2non/bimg), [sharp
for Go](https://github.com/DAddYE/vips), [Ruby on
Rails](http://edgeguides.rubyonrails.org/active_storage_overview.html),
[carrierwave-vips](https://github.com/eltiare/carrierwave-vips),
[mediawiki](http://www.mediawiki.org/wiki/Extension:VipsScaler),
[PhotoFlow](https://github.com/aferrero2707/PhotoFlow) and others.
The official libvips GUI is [nip2](https://github.com/libvips/nip2),
a strange combination of a spreadsheet and an photo editor.

# Install

There are packages for most Unix-like operating systems, including
macOS. Check your package manager.

There are binaries for Windows in
[releases](https://github.com/libvips/libvips/releases).

The [libvips website](https://libvips.github.io/libvips) has [detailed
install notes](https://libvips.github.io/libvips/install.html).

# Building libvips from a source tarball

We keep pre-baked tarballs in
[releases](https://github.com/libvips/libvips/releases).

Untar, then in the libvips directory you should just be able to do:

    ./configure

Check the summary at the end of `configure` carefully.  libvips must have
`build-essential`, `pkg-config`, `libglib2.0-dev`, `libexpat1-dev`.

You'll need the dev packages for the file format support you want. For basic
jpeg and tiff support, you'll need `libtiff5-dev`, `libjpeg-turbo8-dev`,
and `libgsf-1-dev`.  See the **Dependencies** section below for a full list
of the things that libvips can be configured to use.

Once `configure` is looking OK, compile and install with the usual:

    make
    sudo make install

By default this will install files to `/usr/local`.

# Testing

Run the test suite with:

    make check

Run a specific test with:

    pytest test/test-suite/test_foreign.py -k test_tiff

# Building libvips from git

Clone the latest sources with:

    git clone git://github.com/libvips/libvips.git

Building from git needs more packages -- you'll need at least `gtk-doc` 
and `gobject-introspection`, see the dependencies section below. For example:

    brew install gtk-doc 

Then generate the build system with:

    ./autogen.sh --prefix=/home/john/vips

Debug build:

    CFLAGS="-g -Wall" CXXFLAGS="-g -Wall" \
      ./configure --prefix=/home/john/vips --enable-debug
    make
    make install

# Dependencies 

libvips has to have `libglib2.0-dev` and `libexpat1-dev`. Other dependencies
are optional.

## Optional dependencies

If suitable versions are found, libvips will add support for the following
libraries automatically. See `./configure --help` for a set of flags to
control library detection. Packages are generally found with `pkg-config`,
so make sure that is working.

Libraries like giflib and nifti do not use `pkg-config` so libvips will also
look for them in the default path and in `$prefix`. If you have installed
your own versions of these libraries in a different location, libvips will
not see them. Use switches to libvips configure like:

    ./configure --prefix=/Users/john/vips \
      --with-giflib-includes=/opt/local/include \
      --with-giflib-libraries=/opt/local/lib 

or perhaps:

    CFLAGS="-g -Wall -I/opt/local/include -L/opt/local/lib" \
      CXXFLAGS="-g -Wall -I/opt/local/include -L/opt/local/lib" \
      ./configure --prefix=/Users/john/vips 

### libjpeg

The IJG JPEG library. Use the `-turbo` version if you can. 

### libexif

If available, libvips adds support for EXIF metadata in JPEG files.

### giflib

The standard gif loader. If this is not present, vips will try to load gifs
via imagemagick instead.

### librsvg

The usual SVG loader. If this is not present, vips will try to load SVGs
via imagemagick instead.

### PDFium

If present, libvips will attempt to load PDFs with PDFium. Download the 
prebuilt pdfium binary from: 

    https://github.com/bblanchon/pdfium-binaries

Untar to the libvips install prefix, for example:

    cd ~/vips
    tar xf ~/pdfium-linux.tgz

Create a `pdfium.pc` like this (update the version number):

    VIPSHOME=/home/john/vips
    cat > $VIPSHOME/lib/pkgconfig/pdfium.pc << EOF
         prefix=$VIPSHOME
         exec_prefix=\${prefix}
         libdir=\${exec_prefix}/lib
         includedir=\${prefix}/include
         Name: pdfium
         Description: pdfium
         Version: 4290
         Requires:
         Libs: -L\${libdir} -lpdfium
         Cflags: -I\${includedir}
    EOF

If PDFium is not detected, libvips will look for poppler-glib instead.

### poppler-glib

The Poppler PDF renderer, with a glib API. If this is not present, vips
will try to load PDFs via imagemagick.

### libgsf-1

If available, libvips adds support for creating image pyramids with `dzsave`. 

### libtiff

The TIFF library. It needs to be built with support for JPEG and
ZIP compression. 3.4b037 and later are known to be OK. 

### fftw3

If libvips finds this library, it uses it for fourier transforms. 

### lcms2

If present, `vips_icc_import()`, `vips_icc_export()` and `vips_icc_transform()`
are available for transforming images with ICC profiles. 

### libspng

If present, libvips will load PNG files using libspng. At the moment, libpng
is still necessary for save.

### libpng

If libspng is not present and libpng is, libvips will load PNG files with
libpng. It will always save PNG files with libpng.

### libimagequant

If present, libvips can write 8-bit palette-ised PNGs.

### ImageMagick, or optionally GraphicsMagick

If available, libvips adds support for loading all libMagick-supported
image file types. Use `--with-magickpackage=GraphicsMagick` to build against 
graphicsmagick instead.

Imagemagick 6.9+ needs to have been built with `--with-modules`. Most packaged
IMs are, I think.

If you are going to be using libvips with untrusted images, perhaps in a
web server, for example, you should consider the security implications of
enabling a package with such a large attack surface. 

### pangoft2

If available, libvips adds support for text rendering. You need the
package pangoft2 in `pkg-config --list-all`.

### orc-0.4

If available, vips will accelerate some operations with this run-time
compiler.

### matio

If available, vips can load images from Matlab save files.

### cfitsio

If available, vips can load FITS images.

### libwebp

If available, vips can load and save WebP images.

### libniftiio

If available, vips can load and save NIfTI images.

### OpenEXR

If available, libvips will directly read (but not write, sadly)
OpenEXR images.

### OpenSlide

If available, libvips can load OpenSlide-supported virtual slide
files: Aperio, Hamamatsu, Leica, MIRAX, Sakura, Trestle, and Ventana.

### libheif

If available, libvips can load and save HEIC images. 

# Contributors

### Code Contributors

This project exists thanks to all the people who contribute. 

<a href="https://github.com/libvips/libvips/graphs/contributors"><img src="https://opencollective.com/libvips/contributors.svg?width=890&button=false" /></a>

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