VIPS from the command-line
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VIPS Library

# Using VIPS

How to use the VIPS library from the command-line

## Using VIPS 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 `vips_gamma()` if you need more information.

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`.

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.