libvips/README.md
2022-02-08 18:28:35 +00:00

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# 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](https://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](https://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, JPEG2000, JPEG-XL,
TIFF, PNG, WebP, HEIC, AVIF, 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](https://libvips.github.io/libvips/API/current/using-from-c.html),
[C++](https://libvips.github.io/libvips/API/current/using-from-cpp.html),
and the
[command-line](https://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](https://edgeguides.rubyonrails.org/active_storage_overview.html),
[carrierwave-vips](https://github.com/eltiare/carrierwave-vips),
[mediawiki](https://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 a 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 from source
libvips uses the [Meson build system](https://mesonbuild.com), version 0.56 or
later, with [ninja](https://ninja-build.org).
To compile, libvips must have `build-essential`, `pkg-config`,
`libglib2.0-dev`, `libexpat1-dev`. See the **Dependencies** section below
for a full list of the libvips optional dependencies.
## Cheatsheet
```
cd libvips-x.y.x
meson setup build --prefix=/aaa/bbb/ccc
cd build
ninja
ninja install
```
Notes:
- Check the output of `meson setup` carefully and make sure it found
everything you wanted it to find.
- Add flags like `-Dnsgif=false` to turn options on and off, see
`meson_options.txt` for a list of all the build options libvips supports.
- Add `--buildtype=release` for a release (optimised) build.
- You might need to add `--libdir=lib` on Debian if you don't want the arch
name in the library path.
- Use `--default-library=static` for a static build.
- Use `ninja test` to run the tests.
- There's a more comprehensive test suite you can run with `pytest`.
## Optional dependencies
If suitable versions are found, libvips will add support for the following
libraries automatically. Packages are generally found with `pkg-config`,
so make sure that is working.
### libjpeg
The IJG JPEG library. Use the `-turbo` version if you can.
### libexif
If available, libvips adds support for EXIF metadata in JPEG files.
### 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()`
can be used to manipulate 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, quantizr
If one of these quantisation packages is present, libvips can write 8-bit
palette-ised PNGs and GIFs.
### ImageMagick, or optionally GraphicsMagick
If available, libvips adds support for loading and saving all
libMagick-supported image file types. You can enable and disable load and save
separately.
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.
### pangocairo
If available, libvips adds support for text rendering. You need the
package pangocairo 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.
### OpenJPEG
If available, libvips will read and write JPEG2000 images.
### libjxl
If available, libvips will read and write JPEG-XL 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 and AVIF images. Your libheif (in
turn) needs to be built with the correct decoders and encoders. You can check
with eg.:
```
$ pkg-config libheif --print-variables
builtin_avif_decoder
builtin_avif_encoder
builtin_h265_decoder
builtin_h265_encoder
exec_prefix
includedir
libdir
pcfiledir
prefix
```
# Contributors
### Code Contributors
This project exists thanks to all the people who contribute.
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