Add the Image Color Palette node (#1311)

* Add image color palette node

* Add max size of palette

* Code review cleanup

---------

Co-authored-by: 0hypercube <0hypercube@gmail.com>
Co-authored-by: Keavon Chambers <keavon@keavon.com>

node-graph/gstd/src/image_color_palette.rs

@@ -0,0 +1,83 @@
+use graphene_core::raster::ImageFrame;
+use graphene_core::Color;
+use graphene_core::Node;
+
+#[derive(Debug, Clone)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct ImageColorPaletteNode<MaxSize> {
+	max_size: MaxSize,
+}
+
+#[node_macro::node_fn(ImageColorPaletteNode)]
+fn image_color_palette(frame: ImageFrame<Color>, max_size: u32) -> Vec<Color> {
+	const GRID: f32 = 3.0;
+
+	let bins = GRID * GRID * GRID;
+
+	let mut histogram: Vec<usize> = vec![0; (bins + 1.0) as usize];
+	let mut colors: Vec<Vec<Color>> = vec![vec![]; (bins + 1.0) as usize];
+
+	for pixel in frame.image.data.iter() {
+		let r = pixel.r() * GRID;
+		let g = pixel.g() * GRID;
+		let b = pixel.b() * GRID;
+
+		let bin = (r * GRID + g * GRID + b * GRID) as usize;
+
+		histogram[bin] += 1;
+		colors[bin].push(pixel.to_gamma_srgb());
+	}
+
+	let shorted = histogram.iter().enumerate().filter(|(_, &count)| count > 0).map(|(i, _)| i).collect::<Vec<usize>>();
+
+	let mut palette = vec![];
+
+	for i in shorted.iter().take(max_size as usize) {
+		let list = colors[*i].clone();
+
+		let mut r = 0.0;
+		let mut g = 0.0;
+		let mut b = 0.0;
+		let mut a = 0.0;
+
+		for color in list.iter() {
+			r += color.r();
+			g += color.g();
+			b += color.b();
+			a += color.a();
+		}
+
+		r /= list.len() as f32;
+		g /= list.len() as f32;
+		b /= list.len() as f32;
+		a /= list.len() as f32;
+
+		let color = Color::from_rgbaf32(r, g, b, a).unwrap();
+
+		palette.push(color);
+	}
+
+	return palette;
+}
+
+#[cfg(test)]
+mod test {
+	use graphene_core::{raster::Image, value::CopiedNode};
+
+	use super::*;
+
+	#[test]
+	fn test_image_color_palette() {
+		assert_eq!(
+			ImageColorPaletteNode { max_size: CopiedNode(1u32) }.eval(ImageFrame {
+				image: Image {
+					width: 100,
+					height: 100,
+					data: vec![Color::from_rgbaf32(0.0, 0.0, 0.0, 1.0).unwrap(); 10000],
+				},
+				..Default::default()
+			}),
+			[Color::from_rgbaf32(0.0, 0.0, 0.0, 1.0).unwrap()]
+		);
+	}
+}

node-graph/gstd/src/lib.rs

@@ -21,6 +21,8 @@ pub use graphene_core::*;
 
 pub mod image_segmentation;
 
+pub mod image_color_palette;
+
 pub mod brush;
 
 #[cfg(feature = "wasm")]