From 918ed53f49cedd63e8d70a21add4075f4e672ef3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Sat, 23 Sep 2023 11:45:17 +0200
Subject: [PATCH] Add images.Process filter

This allows for constructs like:

```
{{ $filters := slice (images.GaussianBlur 8) (images.Grayscale) (images.Process "jpg q30 resize 200x") }}
{{ $img = $img | images.Filter $filters }}
```

Note that the `action` option in `images.Process` is optional (`resize` in the example above), so you can use the above to just set the target format, e.g.:

```
{{ $filters := slice (images.GaussianBlur 8) (images.Grayscale) (images.Process "jpg") }}
{{ $img = $img | images.Filter $filters }}
```

Fixes #8439
---
 content/en/functions/images/index.md | 35 ++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/content/en/functions/images/index.md b/content/en/functions/images/index.md
index fcd0796e3..2b106714e 100644
--- a/content/en/functions/images/index.md
+++ b/content/en/functions/images/index.md
@@ -12,6 +12,28 @@ toc: true
 
 See [images.Filter](#filter) for how to apply these filters to an image.
 
+## Process
+
+{{< new-in "0.119.0" >}}
+
+{{% funcsig %}}
+images.Overlay SRC SPEC
+{{% /funcsig %}}
+
+A general purpose image processing function.
+
+This filter has all the same options as the [Process](/content-management/image-processing/#process) method, but using it as a filter may be more effective if you need to apply multiple filters to an image:
+
+```go-html-template
+{{ $filters := slice 
+  images.Grayscale
+  (images.GaussianBlur 8)
+  (images.Process "resize 200x jpg q30") 
+}}
+{{ $img = $img | images.Filter $filters }}
+```
+
+
 ## Overlay
 
 {{% funcsig %}}
@@ -36,6 +58,8 @@ The above will overlay `$logo` in the upper left corner of `$img` (at position `
 
 ## Opacity
 
+{{< new-in "0.119.0" >}}
+
 {{% funcsig %}}
 images.Opacity SRC OPACITY
 {{% /funcsig %}}
@@ -47,6 +71,15 @@ The OPACITY parameter must be in range (0, 1).
 {{ $img := $img.Filter (images.Opacity 0.5 )}}
 ```
 
+Note that target format must support transparency, e.g. PNG. If the source image is e.g. JPG, the most effective way would be to combine it with the [`Process`] filter:
+
+```go-html-template
+{{ $png := $jpg.Filter 
+  (images.Opacity 0.5)
+  (images.Process "png") 
+}}
+```
+
 ## Text
 
 Using the `Text` filter, you can add text to an image.
@@ -237,3 +270,5 @@ images.ImageConfig PATH
 favicon.ico: {{ .Width }} x {{ .Height }}
 {{ end }}
 ```
+
+[`Process`]: #process
\ No newline at end of file