VIPS from the command-line1VIPS LibraryUsing VIPSHow to use the VIPS library from the command-lineIntroduction
Use the vips command to execute VIPS operations from
the command-line. For example:
$ vips rot k2.jpg x.jpg d90
Will rotate the image k2.jpg by 90 degrees
anticlockwise and write the result to the file x.jpg.
If you don't give any arguments to an operation,
vips will give a short description, for example:
$ vips rot
rotate an image
usage:
rot in out angle
where:
in - Input image, input VipsImage
out - Output image, output VipsImage
angle - Angle to rotate image, input VipsAngle
default: d90
allowed: d0, d90, d180, d270
There's a straightforward relationship with the C API: compare this to
the API docs for vips_rot(), for example.
Listing all operations
You can list all classes with:
$ vips list classes
...
VipsOperation (operation), operations
VipsSystem (system), run an external command
VipsArithmetic (arithmetic), arithmetic operations
VipsBinary (binary), binary operations
VipsAdd (add), add two images
... etc.
Each line shows the canonical name of the class (for example
VipsAdd), the class nickname
(add in this case), and a short description.
Some subclasses of operation will show more: for example, subclasses of
VipsForeign will show some of the extra flags
supported by the file load/save operations.
Optional arguments
Many operations take optional arguments. You can supply these as
command-line options, for example:
$ vips gamma
gamma an image
usage:
gamma in out
where:
in - Input image, input VipsImage
out - Output image, output VipsImage
optional arguments:
exponent - Gamma factor, input gdouble
default: 2.4
min: 1e-06, max: 1000
operation flags: sequential-unbuffered
vips_gamma() applies a gamma factor to an image. By
default, it uses 2.4, the sRGB gamma factor, but you can specify any
gamma with the exponent option.
Use it from the command-line like this:
$ vips gamma k2.jpg x.jpg --exponent 0.42
This will read file k2.jpg, un-gamma it, and
write the result to file x.jpg.
Array arguments
Some operations take arrays of values as arguments, for example,
vips_affine() needs an array of four numbers for the
2x2 transform matrix. You pass arrays as space-separated lists, for
example:
$ vips affine k2.jpg x.jpg "2 0 0 1"
You may need the quotes to stop your shell breaking the argument at
the spaces. vips_bandjoin() needs an array of input images to
join, run it like this:
$ vips bandjoin "k2.jpg k4.jpg" x.tif
Implicit file format conversionvips will automatically convert between image file
formats for you. Input images are detected by sniffing their first few
bytes; output formats are set from the filename suffix. You can see a
list of all the supported file formats with something like:
$ vips list classes | grep -i foreign
Then get a list of the options a format supports with, for example:
$ vips jpegsave
You can pass options to the implicit load and save operations enclosed
in square brackets after the filename. For example:
vips affine k2.jpg x.jpg[Q=90,strip] "2 0 0 1"
Will write x.jpg at quality level 90 and will
strip all metadata from the image.
Other features
Finally, vips has a couple of useful extra options.
Use to get
vips to display a simple progress indicator.
Use and vips will
leak-test on exit, and also display an estimate of peak memory use.
VIPS comes with a couple of other useful programs.
vipsheader is a command which can print image header
fields. vipsedit can change fields in vips format
images. vipsthumbnail can make image thumbnails
quickly.