Add Minimum and Maximum option to Threshold node (#1029)

This might be usefull later when spliting Images into Seperate Images for each Channel, as then the other modes might behave weirdly

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

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

@@ -11,11 +11,19 @@ pub enum LuminanceCalculation {
 	SRGB,
 	Perceptual,
 	AverageChannels,
+	MinimumChannels,
+	MaximumChannels,
 }
 
 impl LuminanceCalculation {
-	pub fn list() -> [LuminanceCalculation; 3] {
-		[LuminanceCalculation::SRGB, LuminanceCalculation::Perceptual, LuminanceCalculation::AverageChannels]
+	pub fn list() -> [LuminanceCalculation; 5] {
+		[
+			LuminanceCalculation::SRGB,
+			LuminanceCalculation::Perceptual,
+			LuminanceCalculation::AverageChannels,
+			LuminanceCalculation::MinimumChannels,
+			LuminanceCalculation::MaximumChannels,
+		]
 	}
 }
 
@@ -25,6 +33,8 @@ impl std::fmt::Display for LuminanceCalculation {
 			LuminanceCalculation::SRGB => write!(f, "sRGB"),
 			LuminanceCalculation::Perceptual => write!(f, "Perceptual"),
 			LuminanceCalculation::AverageChannels => write!(f, "Average Channels"),
+			LuminanceCalculation::MinimumChannels => write!(f, "Minimum Channels"),
+			LuminanceCalculation::MaximumChannels => write!(f, "Maximum Channels"),
 		}
 	}
 }
@@ -43,6 +53,8 @@ fn luminance_color_node(color: Color, luma_calculation: LuminanceCalculation) ->
 		LuminanceCalculation::SRGB => color.luminance_srgb(),
 		LuminanceCalculation::Perceptual => color.luminance_perceptual(),
 		LuminanceCalculation::AverageChannels => color.average_rgb_channels(),
+		LuminanceCalculation::MinimumChannels => color.minimum_rgb_channels(),
+		LuminanceCalculation::MaximumChannels => color.maximum_rgb_channels(),
 	};
 
 	// TODO: Remove conversion to linear when the whole node graph uses linear color
@@ -188,6 +200,8 @@ fn threshold_node(color: Color, luma_calculation: LuminanceCalculation, threshol
 		LuminanceCalculation::SRGB => color.luminance_srgb(),
 		LuminanceCalculation::Perceptual => color.luminance_perceptual(),
 		LuminanceCalculation::AverageChannels => color.average_rgb_channels(),
+		LuminanceCalculation::MinimumChannels => color.minimum_rgb_channels(),
+		LuminanceCalculation::MaximumChannels => color.maximum_rgb_channels(),
 	};
 
 	if luminance >= threshold {

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

@@ -200,6 +200,14 @@ impl Color {
 		(self.red + self.green + self.blue) / 3.
 	}
 
+	pub fn minimum_rgb_channels(&self) -> f32 {
+		self.red.min(self.green).min(self.blue)
+	}
+
+	pub fn maximum_rgb_channels(&self) -> f32 {
+		self.red.max(self.green).max(self.blue)
+	}
+
 	// From https://stackoverflow.com/a/56678483/775283
 	pub fn luminance_srgb(&self) -> f32 {
 		0.2126 * self.red + 0.7152 * self.green + 0.0722 * self.blue