Added saturate script function (+documentation), it also desaturates

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@800 0fc631ac-6414-0410-93d0-97cfa31319b6

doc/function/index.txt

@@ -67,7 +67,8 @@ These functions are built into the program, other [[type:function]]s can be defi
 | [[fun:combine_blend]]		Blend two images together using a given [[type:combine|combining mode]].
 | [[fun:set_mask]]		Set the transparancy mask of an image.
 | [[fun:set_alpha]]		Change the transparency of an image.
-| [[fun:set_combine]]		Chnage how the image should be combined with the background.
+| [[fun:set_combine]]		Change how the image should be combined with the background.
+| [[fun:saturate]]		Saturate/desaturate an image.
 | [[fun:enlarge]]		Enlarge an image by putting a border around it.
 | [[fun:crop]]		Crop an image, giving only a small subset of it.
 | [[fun:drop_shadow]]		Add a drop shadow to an image.

doc/function/saturate.txt

@@ -0,0 +1,21 @@
+Function: saturate
+
+--Usage--
+> saturate(input: image, amount: saturation amount)
+
+Saturate or desaturate an image. Saturation makes the colors brighter, desaturation makes the image more grey.
+
+To saturate use an amount between @0@ (no saturation) and @1@ (super crazy, too much saturation).
+
+To desaturate use an amount between @0@ (no desaturation) and @-1@ (convert to greyscale).
+
+--Parameters--
+! Parameter	Type			Description
+| @input@	[[type:image]]		Image to (de)saturate.
+| @alpha@	[[type:double]]		Saturation factor.
+
+--Examples--
+> saturate("image5.png", amount:  0.5)  ==  [[Image]]
+>>> saturate(<img src="image5.png" alt='"image5.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />, amount:  0.5) == <img src="image_saturate1.png" alt='"image_saturate1.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />
+> saturate("image5.png", amount: -0.5)  ==  [[Image]]
+>>> saturate(<img src="image5.png" alt='"image5.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />, amount: -0.5) == <img src="image_saturate2.png" alt='"image_saturate2.png"' style="border:1px solid black;vertical-align:middle;margin:1px;" />