Add Levels adjustment node (#1028)

* Add Levels Node

* Fix naming and algorithm

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/messages/portfolio/document/node_graph/node_graph_message_handler/document_node_types.rs

@@ -192,6 +192,45 @@ fn static_nodes() -> Vec<DocumentNodeType> {
 			outputs: vec![DocumentOutputType::new("Image", FrontendGraphDataType::Raster)],
 			properties: |_document_node, _node_id, _context| node_properties::string_properties("Creates an embedded image with the given transform"),
 		},
+		DocumentNodeType {
+			name: "Levels",
+			category: "Image Adjustments",
+			identifier: NodeImplementation::proto("graphene_core::raster::LevelsNode<_, _, _, _, _>"),
+			inputs: vec![
+				DocumentInputType {
+					name: "Image",
+					data_type: FrontendGraphDataType::Raster,
+					default: NodeInput::value(TaggedValue::Image(Image::empty()), true),
+				},
+				DocumentInputType {
+					name: "Shadows",
+					data_type: FrontendGraphDataType::Number,
+					default: NodeInput::value(TaggedValue::F64(0.), false),
+				},
+				DocumentInputType {
+					name: "Midtones",
+					data_type: FrontendGraphDataType::Number,
+					default: NodeInput::value(TaggedValue::F64(50.), false),
+				},
+				DocumentInputType {
+					name: "Highlights",
+					data_type: FrontendGraphDataType::Number,
+					default: NodeInput::value(TaggedValue::F64(100.), false),
+				},
+				DocumentInputType {
+					name: "Output Minimums",
+					data_type: FrontendGraphDataType::Number,
+					default: NodeInput::value(TaggedValue::F64(0.), false),
+				},
+				DocumentInputType {
+					name: "Output Maximums",
+					data_type: FrontendGraphDataType::Number,
+					default: NodeInput::value(TaggedValue::F64(100.), false),
+				},
+			],
+			outputs: vec![DocumentOutputType::new("Image", FrontendGraphDataType::Raster)],
+			properties: node_properties::levels_properties,
+		},
 		DocumentNodeType {
 			name: "Grayscale",
 			category: "Image Adjustments",

editor/src/messages/portfolio/document/node_graph/node_graph_message_handler/node_properties.rs

@@ -199,6 +199,22 @@ pub fn input_properties(_document_node: &DocumentNode, _node_id: NodeId, _contex
 	vec![LayoutGroup::Row { widgets: vec![information] }, LayoutGroup::Row { widgets: vec![refresh_button] }]
 }
 
+pub fn levels_properties(document_node: &DocumentNode, node_id: NodeId, _context: &mut NodePropertiesContext) -> Vec<LayoutGroup> {
+	let input_shadows = number_widget(document_node, node_id, 1, "Shadows", NumberInput::default().min(0.).max(100.).unit("%"), true);
+	let input_midtones = number_widget(document_node, node_id, 2, "Midtones", NumberInput::default().min(0.).max(100.).unit("%"), true);
+	let input_highlights = number_widget(document_node, node_id, 3, "Highlights", NumberInput::default().min(0.).max(100.).unit("%"), true);
+	let output_minimums = number_widget(document_node, node_id, 4, "Output Minimums", NumberInput::default().min(0.).max(100.).unit("%"), true);
+	let output_maximums = number_widget(document_node, node_id, 5, "Output Maximums", NumberInput::default().min(0.).max(100.).unit("%"), true);
+
+	vec![
+		LayoutGroup::Row { widgets: input_shadows },
+		LayoutGroup::Row { widgets: input_midtones },
+		LayoutGroup::Row { widgets: input_highlights },
+		LayoutGroup::Row { widgets: output_minimums },
+		LayoutGroup::Row { widgets: output_maximums },
+	]
+}
+
 pub fn grayscale_properties(document_node: &DocumentNode, node_id: NodeId, _context: &mut NodePropertiesContext) -> Vec<LayoutGroup> {
 	const MIN: f64 = -200.;
 	const MAX: f64 = 300.;

node-graph/gcore/src/raster/adjustments.rs

@@ -51,6 +51,47 @@ fn luminance_color_node(color: Color, luma_calculation: LuminanceCalculation) ->
 	color.map_rgb(|_| luminance)
 }
 
+#[derive(Debug, Clone, Copy, Default)]
+pub struct LevelsNode<InputStart, InputMid, InputEnd, OutputStart, OutputEnd> {
+	input_start: InputStart,
+	input_mid: InputMid,
+	input_end: InputEnd,
+	output_start: OutputStart,
+	output_end: OutputEnd,
+}
+
+// From https://stackoverflow.com/questions/39510072/algorithm-for-adjustment-of-image-levels
+#[node_macro::node_fn(LevelsNode)]
+fn levels_node(color: Color, input_start: f64, input_mid: f64, input_end: f64, output_start: f64, output_end: f64) -> Color {
+	// Input Range
+	let input_shadows = (input_start / 100.) as f32;
+	let input_midtones = (input_mid / 100.) as f32;
+	let input_highlights = (input_end / 100.) as f32;
+
+	// Output Range
+	let output_minimums = (output_start / 100.) as f32;
+	let output_maximums = (output_end / 100.) as f32;
+
+	// Midtones interpolation factor between minimums and maximums
+	let midtones = output_minimums + (output_maximums - output_minimums) * input_midtones;
+
+	// Gamma correction
+	let gamma = if midtones < 0.5 {
+		(1. + (9. * (1. - midtones * 2.))).min(9.99)
+	} else {
+		((1. - midtones) * 2.).max(0.01)
+	};
+
+	// Input levels
+	let color = color.map_rgb(|channel| (channel - input_shadows) / (input_highlights - input_shadows));
+
+	// Midtones
+	let color = color.map_rgb(|channel| channel.powf(gamma));
+
+	// Output levels
+	color.map_rgb(|channel| channel * (output_maximums - output_minimums) + output_minimums)
+}
+
 #[derive(Debug, Clone, Copy, Default)]
 pub struct GrayscaleNode<Tint, Reds, Yellows, Greens, Cyans, Blues, Magentas> {
 	tint: Tint,

node-graph/interpreted-executor/src/node_registry.rs

@@ -30,19 +30,26 @@ macro_rules! register_node {
 			|args| {
 				let mut args = args.clone();
 				args.reverse();
-				let node = <$path>::new($(graphene_std::any::input_node::<$type>(args.pop().expect("not enough arguments provided to construct node"))),*);
+				let node = <$path>::new($(
+					graphene_std::any::input_node::<$type>(
+						args.pop().expect("not enough arguments provided to construct node")
+					)
+				),*);
 				let any: DynAnyNode<$input, _, _> = graphene_std::any::DynAnyNode::new(graphene_core::value::ValueNode::new(node));
 				Box::pin(any)
-			},{
+			},
+			{
 				let node = IdNode::new().into_type_erased();
 				let node = NodeContainer::new(node, vec![]);
 				let _node = unsafe { node.erase_lifetime().static_ref() };
-				let node = <$path>::new($(graphene_std::any::input_node::<$type>(_node)),*);
+				let node = <$path>::new($(
+					graphene_std::any::input_node::<$type>(_node)
+				),*);
 				let params = vec![$(concrete!($type)),*];
-				let mut  node_io =  <$path as NodeIO<'_, $input>>::to_node_io(&node, params);
+				let mut node_io = <$path as NodeIO<'_, $input>>::to_node_io(&node, params);
 				node_io.input = concrete!(<$input as StaticType>::Static);
 				node_io
-			}
+			},
 		)
 	};
 }
@@ -50,21 +57,24 @@ macro_rules! raster_node {
 	($path:ty, params: [$($type:ty),*]) => {
 		(
 			NodeIdentifier::new(stringify!($path)),
-				|args| {
-					let mut args = args.clone();
-					args.reverse();
-					let node = <$path>::new($(
-							graphene_core::value::ClonedNode::new(
-							graphene_std::any::input_node::<$type>(args.pop().expect("Not enough arguments provided to construct node"))
-							.eval(()))
-					),*);
-					let map_node = graphene_std::raster::MapImageNode::new(graphene_core::value::ValueNode::new(node));
-					let any: DynAnyNode<Image, _, _> = graphene_std::any::DynAnyNode::new(graphene_core::value::ValueNode::new(map_node));
-					Box::pin(any)
-				}, {
-					let params = vec![$(concrete!($type)),*];
-					NodeIOTypes::new(concrete!(Image), concrete!(Image), params)
-				}
+			|args| {
+				let mut args = args.clone();
+				args.reverse();
+				let node = <$path>::new($(
+					graphene_core::value::ClonedNode::new(
+						graphene_std::any::input_node::<$type>(
+							args.pop().expect("Not enough arguments provided to construct node")
+						).eval(())
+					)
+				),*);
+				let map_node = graphene_std::raster::MapImageNode::new(graphene_core::value::ValueNode::new(node));
+				let any: DynAnyNode<Image, _, _> = graphene_std::any::DynAnyNode::new(graphene_core::value::ValueNode::new(map_node));
+				Box::pin(any)
+			},
+			{
+				let params = vec![$(concrete!($type)),*];
+				NodeIOTypes::new(concrete!(Image), concrete!(Image), params)
+			},
 		)
 	};
 }
@@ -103,6 +113,7 @@ fn node_registry() -> HashMap<NodeIdentifier, HashMap<NodeIOTypes, NodeConstruct
 		),
 		// Filters
 		raster_node!(graphene_core::raster::LuminanceNode<_>, params: [LuminanceCalculation]),
+		raster_node!(graphene_core::raster::LevelsNode<_, _, _, _, _>, params: [f64, f64, f64, f64, f64]),
 		raster_node!(graphene_core::raster::GrayscaleNode<_, _, _, _, _, _, _>, params: [Color, f64, f64, f64, f64, f64, f64]),
 		raster_node!(graphene_core::raster::HueSaturationNode<_, _, _>, params: [f64, f64, f64]),
 		raster_node!(graphene_core::raster::InvertRGBNode, params: []),