feat: add the normalize directive

Author: JonasKruckenberg

docs/directives.md

@@ -205,3 +205,17 @@ Produces a 'negative' of the image.
 import Image from 'example.jpg?invert'
 import Image from 'exmaple.jpg?invert=true'
 ```
+___
+
+### Invert
+• **Keyword**: `invert`
+• **Type**: _boolean_
+
+'Normalizes' the image by stretching its luminance to cover the full dynamic range.
+This Eenhances the output image contrast.
+
+• **Example**:
+```js
+import Image from 'example.jpg?invert'
+import Image from 'exmaple.jpg?invert=true'
+```

src/directives/index.ts

@@ -4,4 +4,5 @@ export * from './rotate'
 export * from './flip'
 export * from './flop'
 export * from './blur'
-export * from './invert'
+export * from './invert'
+export * from './normalize'

src/directives/normalize.ts

@@ -0,0 +1,16 @@
+import { Directive, DirectiveContext, DirectiveOptions } from "../types";
+
+interface FlipOptions {
+    normalize: string
+}
+
+export const normalize:Directive<FlipOptions> = ({ normalize }: DirectiveOptions, ctx: DirectiveContext) => {
+    if (normalize !== '' && normalize !== 'true') return null
+
+    ctx.useParam('normalize')
+    ctx.setMetadata('normalize', true)
+
+    return function normalizeTransform(image) {
+        return image.normalize()
+    }
+}