diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..2af5d3a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+/target
+/.DS_Store
+/.vscode
\ No newline at end of file
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..8d514a5
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,331 @@
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+ "miniz_oxide 0.4.4",
+ "weezl",
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+[[package]]
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..95af9d1
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "octo"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+image="0.23.14"
+
+[profile.release]
+debug = true
\ No newline at end of file
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..d2877f8
--- /dev/null
+++ b/README.md
@@ -0,0 +1,6 @@
+Does quantization in pure rust on Rgba image, using https://crates.io/crates/image
+
+algorithm:
+https://observablehq.com/@tmcw/octree-color-quantization
+
+inspired by to https://github.com/objectProfessionals/movieMaps
\ No newline at end of file
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..0a9c63b
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,359 @@
+use std::{cell::RefCell, rc::Rc};
+
+use image::{Rgba, RgbaImage};
+
+const MAX_LEVEL: usize = 5;
+
+pub fn quantize(image: &RgbaImage, num_colors:usize) -> RgbaImage{
+    let mut quantizer=OctTreeQuantizer::new(num_colors);
+    quantizer.quantize(image)
+}
+
+struct OctTreeQuantizer {
+    root: Rc<RefCell<OctTreeNode>>,
+    reduce_colors: usize,
+    maximum_colors: usize,
+    colors: usize,
+    color_list: Vec<Vec<Option<Rc<RefCell<OctTreeNode>>>>>,
+}
+
+impl OctTreeQuantizer {
+    fn new(num_colors: usize) -> Self {
+        let mut new_quantizer = Self {
+            root: Rc::new(RefCell::new(OctTreeNode::new())),
+            reduce_colors: usize::max(512, num_colors * 2),
+            maximum_colors: num_colors,
+            color_list: vec![],
+            colors: 0,
+        };
+
+        for _ in 0..=MAX_LEVEL {
+            new_quantizer.color_list.push(Vec::new());
+        }
+        new_quantizer
+    }
+
+    pub fn quantize(&mut self, image: &RgbaImage) -> RgbaImage {
+        for y in 0..image.height() {
+            for x in 0..image.width() {
+                self.insert_color(image.get_pixel(x, y), Rc::clone(&self.root));
+
+                if self.colors > self.reduce_colors {
+                    self.reduce_tree(self.reduce_colors);
+                    //reduce sets to None and the code below actually removes nodes from the list
+                    for level in &mut self.color_list {
+                        level.retain(|c| c.is_some());
+                    }
+                }
+            }
+        }
+        let table = self.build_color_table();
+
+        let mut out = RgbaImage::new(image.width(), image.height());
+        for y in 0..image.height() {
+            for x in 0..image.width() {
+                let pixel = image.get_pixel(x, y);
+                if let Some(index) = self.get_index_for_color(pixel, &self.root) {
+                    let color = table.get(index).unwrap();
+                    if let Some(color) = color {
+                        out.put_pixel(x, y, *color);
+                    }
+                }
+            }
+        }
+        out
+    }
+
+    fn get_index_for_color(
+        &self,
+        color: &Rgba<u8>,
+        node: &Rc<RefCell<OctTreeNode>>,
+    ) -> Option<usize> {
+        fn get_index_for_color(
+            quantizer: &OctTreeQuantizer,
+            color: &Rgba<u8>,
+            level: usize,
+            node: &Rc<RefCell<OctTreeNode>>,
+        ) -> Option<usize> {
+            if level > MAX_LEVEL {
+                return None;
+            }
+            let node = Rc::clone(node);
+            let index = get_bitmask(color, &level);
+
+            let node_b = node.borrow();
+            let child = &node_b.leaf[index];
+
+            if let Some(child) = child {
+                let child_b = child.borrow();
+                if child_b.is_leaf {
+                    return Some(child_b.index);
+                } else {
+                    return get_index_for_color(quantizer, color, level + 1, child);
+                }
+            } else {
+                return Some(node_b.index);
+            }
+        }
+
+        get_index_for_color(&self, color, 0, node)
+    }
+
+    fn build_color_table(&mut self) -> Vec<Option<Rgba<u8>>> {
+        //nested function that is called recursively
+        fn build_color_table(
+            quantizer: &mut OctTreeQuantizer,
+            node: &Rc<RefCell<OctTreeNode>>,
+            table: &mut Vec<Option<Rgba<u8>>>,
+            index: usize,
+        ) -> usize {
+            if quantizer.colors > quantizer.maximum_colors {
+                quantizer.reduce_tree(quantizer.maximum_colors);
+            }
+            if node.borrow().is_leaf {
+                {
+                    let node = node.borrow();
+                    let count = node.count;
+                    table[index] = Some(Rgba::from([
+                        (node.total_red / count as u32) as u8,
+                        (node.total_green / count as u32) as u8,
+                        (node.total_blue / count as u32) as u8,
+                        0xFF,
+                    ]));
+                }
+                node.borrow_mut().index = index;
+
+                index + 1
+            } else {
+                let mut result = index;
+                for i in 0..8 {
+                    // cannot iterate leaf, because that widens the scope of the borrow (of node)
+                    let mut node = node.borrow_mut();
+                    if let Some(leaf) = &node.leaf[i] {
+                        //could be immutable borrow
+                        let new_index = build_color_table(quantizer, leaf, table, result);
+                        node.index = index; //but also need mutable borrow here
+                        result = new_index;
+                    }
+                }
+
+                result
+            }
+        }
+
+        let mut table: Vec<Option<Rgba<u8>>> = vec![None; self.colors];
+        let node = Rc::clone(&self.root);
+        build_color_table(self, &node, &mut table, 0);
+        table
+    }
+
+    fn insert_color(&mut self, rgb: &Rgba<u8>, node: Rc<RefCell<OctTreeNode>>) {
+        //nested function that is called recursively
+        fn insert_color(
+            quantizer: &mut OctTreeQuantizer,
+            color: &Rgba<u8>,
+            level: usize,
+            node: Rc<RefCell<OctTreeNode>>,
+        ) {
+            if level > MAX_LEVEL {
+                return;
+            }
+
+            let index = get_bitmask(color, &level);
+
+            if node.borrow().leaf[index].is_none() {
+                let mut child = OctTreeNode::new();
+                child.parent = Some(Rc::clone(&node));
+                child.p_index = quantizer.color_list[level].len();
+
+                if level == MAX_LEVEL {
+                    child.is_leaf = true;
+                    child.count = 1;
+                    child.total_red = color[0] as u32;
+                    child.total_green = color[1] as u32;
+                    child.total_blue = color[2] as u32;
+                    child.level = level;
+                    quantizer.colors += 1;
+                }
+
+                let child = Rc::new(RefCell::new(child));
+                quantizer.color_list[level].push(Some(Rc::clone(&child)));
+                let clone = Rc::clone(&child);
+
+                {
+                    let mut mutnode = node.borrow_mut();
+                    mutnode.children += 1;
+                    mutnode.is_leaf = false;
+                    mutnode.leaf[index] = Some(child);
+                }
+
+                if level < MAX_LEVEL {
+                    insert_color(quantizer, color, level + 1, clone);
+                } else {
+                    return;
+                }
+            } else {
+                if node
+                    .borrow()
+                    .leaf
+                    .get(index)
+                    .unwrap()
+                    .as_ref()
+                    .unwrap()
+                    .borrow()
+                    .is_leaf
+                {
+                    let mut node = node.borrow_mut();
+                    let mut child = node
+                        .leaf
+                        .get_mut(index)
+                        .unwrap()
+                        .as_ref()
+                        .unwrap()
+                        .borrow_mut();
+                    child.count += 1;
+                    child.total_red += color[0] as u32;
+                    child.total_green += color[1] as u32;
+                    child.total_blue += color[2] as u32;
+                    return;
+                } else {
+                    insert_color(
+                        quantizer,
+                        color,
+                        level + 1,
+                        Rc::clone(&(node.borrow().leaf[index]).as_ref().unwrap()),
+                    );
+                }
+            }
+        }
+
+        insert_color(self, rgb, 0, node);
+    }
+
+    fn reduce_tree(&mut self, num_colors: usize) {
+        // Nested function that is called recursively
+        fn reduce_tree(quantizer: &mut OctTreeQuantizer, num_colors: usize, level: isize) {
+            if level < 0 {
+                return;
+            } else {
+                let mut removals = Vec::new();
+                let list = &quantizer.color_list[level as usize];
+                for node in list {
+                    if let Some(node) = node {
+                        if node.borrow().children > 0 {
+                            for i in 0..8 {
+                                let mut color: Option<(usize, u32, u32, u32, usize)> = None;
+
+                                if let Some(child) = node.borrow().leaf.get(i) {
+                                    if let Some(child) = child {
+                                        let child = child.borrow();
+                                        color = Some((
+                                            child.count,
+                                            child.total_red,
+                                            child.total_green,
+                                            child.total_blue,
+                                            child.p_index,
+                                        ));
+                                    }
+                                }
+
+                                // need to mutate node, which conflicts with previous borrow to retrieve the child
+                                if let Some(color) = color {
+                                    let mut node = node.borrow_mut();
+                                    node.count += color.0;
+                                    node.total_red += color.1;
+                                    node.total_green += color.2;
+                                    node.total_blue += color.3;
+                                    node.leaf[i] = None;
+                                    node.children -= 1;
+                                    quantizer.colors -= 1;
+
+                                    removals.push(color.4); //save for further processing outside loop (and borrow of colorlist)
+                                }
+                            }
+                            node.borrow_mut().is_leaf = true;
+                            quantizer.colors += 1;
+                            if quantizer.colors <= num_colors {
+                                return;
+                            }
+                        }
+                    }
+                }
+                let color_list = &mut quantizer.color_list[(level as usize + 1)];
+                for index in removals {
+                    color_list[index] = None; //set to None here, Option removed later
+                }
+
+                reduce_tree(quantizer, num_colors, level - 1);
+            }
+        }
+
+        // call to nested function
+        reduce_tree(self, num_colors, (MAX_LEVEL - 1) as isize);
+    }
+}
+
+struct OctTreeNode {
+    children: usize,
+    level: usize,
+    parent: Option<Rc<RefCell<OctTreeNode>>>,
+    leaf: Vec<Option<Rc<RefCell<OctTreeNode>>>>,
+    is_leaf: bool,
+    count: usize,
+    total_red: u32,
+    total_green: u32,
+    total_blue: u32,
+    index: usize,
+    p_index: usize,
+}
+
+impl OctTreeNode {
+    fn new() -> Self {
+        Self {
+            children: 0,
+            level: 0,
+            parent: None,
+            leaf: vec![None; 8],
+            is_leaf: false,
+            count: 0,
+            total_red: 0,
+            total_green: 0,
+            total_blue: 0,
+            index: 0,
+            p_index: 0,
+        }
+    }
+}
+
+fn get_bitmask(color: &Rgba<u8>, level: &usize) -> usize {
+    let bit = 0x80 >> level;
+
+    let mut index = 0;
+    if (color[0] & bit) != 0 {
+        index += 4;
+    }
+    if (color[1] & bit) != 0 {
+        index += 2;
+    }
+    if (color[2] & bit) != 0 {
+        index += 1;
+    }
+    index
+}
+
+ #[cfg(test)]
+mod test {
+
+    use image::ImageError;
+
+    use super::*;
+
+    #[test]
+    fn test_big_image() -> Result<(), ImageError> {
+        let src: RgbaImage = image::open("testdata/input.jpg").unwrap().into_rgba8();
+
+        let out = quantize(&src, 256);
+        out.save_with_format("output.jpg", image::ImageFormat::Jpeg)?;
+        Ok(())
+    }
+}
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