This manual refers to a future version of the software that is still in development. It may be incomplete or inaccurate and the software may change before a final release.


Redactions are black rectangles that are overlaid onto source images in order to obscure parts of them. This can be used for copyright protection, privacy protection, or censorship, without altering any source images. Different redactions can be applied to the same image dynamically for different audiences based on client IP address, cookies, and more.

Redactions are defined with x, y, width, and height properties corresponding to source image coordinates. Redacted regions will be blacked out at every intersecting crop region and scale.

Original image
Redactions applied

The redaction feature works via the delegate script. With the delegate script enabled, redactions.enabled must be set to true in the configuration file. The delegate script must implement a method called redactions() that returns an array of source image redaction coordinates in response to a particular request.


class CustomDelegate
  def redactions(options = {})
    redactions = []
    # Add two redactions to an image with an identifier of "sample" for all
    # clients except localhost.
    if context['identifier'] == 'sample'
      unless %w( ::1/128).include?(context['client_ip'])
        redactions << {
            'x' => 50,
            'y' => 65,
            'width' => 120,
            'height' => 105
        redactions << {
            'x' => 673,
            'y' => 812,
            'width' => 1320,
            'height' => 620

Processor Support

Not all processors support redaction; see the table of processor-supported features.