VIPS from the command-lineUsing VIPS — How to use the VIPS library from the command-line |
Use the vips command to execute VIPS operations from the command-line. You can show all classes with:
vips list classes
This produces output something like:
VipsOperation (operation), operations
VipsSystem (system), run an external command
VipsArithmetic (arithmetic), arithmetic operations
VipsBinary (binary), binary operations
VipsAdd (add), add two images
.... and so on
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.
You can get help on a specific operation by running it with no arguments,
for example:
vips gamma
produces the output:
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
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. You can use the
C API docs for
if you need more
information.
Use it from the command-line like this:
vips_gamma()
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
.
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"
Or vips bandjoin needs an array of input images to join, run it like this:
vips bandjoin "k2.jpg k4.jpg" x.tif
vips 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.
Finally, vips has a couple of useful extra options.
Use --vips-progress
to get
vips to display a simple progress indicator.
Use --vips-leak
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.