Extra Params

Extra Parameters #

You can turn it on by setting "ENABLE_EXTRA_PARAMS": true in config.json.

Currently, we support the following params:

  • height
  • width
  • max_width
  • max_height

both are in px.

Example on height and width #



If you set both width and height, your image will be cropped using attention crop by default maintain your width-height ratio, like this:




attention crop: look for features likely to draw human attention.

You can use EXTRA_PARAMS_CROP_INTERESTING config to change crop interesting, configuration example at Configuration page.

More examples can be found on our blog post: How does different VipsInteresting values in libvips determine the cropping position of an image?.

Note on max_height and max_width #

These two parameters are used to limit the maximum size of the image and will limit large-size images within these two dimensions while keeping small-size images unchanged.

For example, we have a 500x500px image called big.jpg. When you visit /big.jpg?max_height=200&max_width=100, since max_width is smaller, the image will be scaled to 100x100px.

If we have an 80x80px image called small.jpg, when you visit /small.jpg?max_height=200&max_width=100, since the length and width of the image are within range, this image will not be processed.

This new feature is mainly in response to the demand at: https://github.com/webp-sh/webp_server_go/issues/305.

More details #

Non Remote Backend #

When you’re not using Remote Backend, suppose your image is at /home/webp_server/exhaust/path/to/tsuki.jpg, and ENABLE_EXTRA_PARAMS is enabled.

  • When requesting image at http://some-host.tld/path/to/tsuki.jpg, the optimized image will be at /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp_width=0&height=0
  • When requesting image at http://some-host.tld/path/to/tsuki.jpg?width=200, the image will be compressed to width of 200px, height/width ratio will remain the same, and the optimized image will be at /home/webp_server/exhaust/path/to/tsuki.jpg.1582558990.webp_width=200&height=0

Remote Backend #

ENABLE_EXTRA_PARAMS is currently available in Remote Backend.