images.Sigmoid

This is a non-linear contrast change useful for photo adjustments; it preserves highlight and shadow detail.

The midpoint is the midpoint of contrast. It must be in the range [0, 1], typically 0.5.

The factor indicates how much to increase or decrease the contrast, typically in the range [-10, 10] where 0 has no effect. A positive value increases contrast, while a negative value decrease contrast.

Usage

Create the filter:

{{ $filter := images.Sigmoid 0.6 -4 }}

Apply the filter using the images.Filter function:

{{ with resources.Get "images/original.jpg" }}
  {{ with . | images.Filter $filter }}
    <img src="{{ .RelPermalink }}" width="{{ .Width }}" height="{{ .Height }}" alt="">
  {{ end }}
{{ end }}

You can also apply the filter using the Filter method on a Resource object:

{{ with resources.Get "images/original.jpg" }}
  {{ with .Filter $filter }}
    <img src="{{ .RelPermalink }}" width="{{ .Width }}" height="{{ .Height }}" alt="">
  {{ end }}
{{ end }}

Example

Original

Processed