diff --git a/src/colours.rs b/src/colours.rs
new file mode 100644
index 0000000..a200727
--- /dev/null
+++ b/src/colours.rs
@@ -0,0 +1,106 @@
+use std::collections::{HashMap, HashSet};
+
+use image::{DynamicImage, GenericImageView, Rgb};
+use log::info;
+use std::fmt::Debug;
+
+use crate::encode_hex;
+
+pub type ColourMap = HashMap<u8, HashMap<u8, HashMap<u8, Vec<Point>>>>;
+pub type Colour = Rgb<u8>;
+
+#[derive(Clone)]
+pub struct Point {
+    x: u32,
+    y: u32,
+}
+
+impl Debug for Point {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&format!("{}, {}", &self.x, &self.y))
+    }
+}
+
+pub struct Match {
+    pub colour: Colour,
+    pub positions: Vec<Point>,
+}
+
+pub fn extract_colours(img: DynamicImage) -> ColourMap {
+    let mut out: ColourMap = HashMap::new();
+    for (x, y, p) in img.pixels() {
+        out.entry(p[0])
+            .or_insert_with(HashMap::new)
+            .entry(p[1])
+            .or_insert_with(HashMap::new)
+            .entry(p[2])
+            .or_insert_with(Vec::new)
+            .push(Point { x, y });
+    }
+    out
+}
+
+fn extract_colours_set(img: DynamicImage) -> HashSet<Rgb<u8>> {
+    let mut out = HashSet::new();
+    img.pixels().for_each(|(_x, _y, p)| {
+        out.insert(p);
+    });
+    out.into_iter().map(|c| Rgb([c[0], c[1], c[2]])).collect()
+}
+
+fn closest_colour(colour: &Colour, all: &ColourMap) -> Option<Match> {
+    // use redmean to calculate the distance between colours
+    let mut closest: Option<Match> = None;
+    let mut dist: f32 = f32::MAX;
+
+    let (colour_r, colour_g, colour_b) = (colour[0] as f32, colour[1] as f32, colour[2] as f32);
+    for (r, gbs) in all.iter() {
+        let r_bar = 0.5 * (*r as f32 + colour_r);
+        let r_squared = (*r as f32 - colour_r) * (*r as f32 - colour_r);
+        for (g, bs) in gbs.iter() {
+            let g_squared = (*g as f32 - colour_g) * (*g as f32 - colour_g);
+            for (b, vec) in bs.iter() {
+                let b_squared = (*b as f32 - colour_b) * (*b as f32 - colour_b);
+                let delta = (2.0 + r_bar / 256.0) * r_squared
+                    + 4.0 * g_squared
+                    + (2.0 + (255.0 - r_bar) / 256.0) * b_squared;
+                if delta < dist {
+                    dist = delta;
+                    closest = Some(Match {
+                        colour: Rgb([*r, *g, *b]),
+                        positions: vec.to_vec(), // FIXME (low priority): would be more efficient if
+                                                 // i can make these a borrow instead, but that
+                                                 // leads to lifetime issues
+                    });
+                }
+            }
+        }
+    }
+    return closest;
+}
+
+pub fn map_image_list(all_cols: &ColourMap, cols: Vec<Colour>) -> HashMap<Colour, Match> {
+    let mut output_cols: HashMap<Colour, Match> = HashMap::new();
+
+    for c in cols {
+        info!("Matching colour {}", encode_hex(&c));
+        if let Some(col) = closest_colour(&c, &all_cols) {
+            output_cols.insert(c, col);
+        }
+    }
+    output_cols
+}
+
+pub fn map_image_image(img_1_cols: &ColourMap, img_2: DynamicImage) -> HashMap<Colour, Match> {
+    let img_2_cols = extract_colours_set(img_2);
+
+    let mut output_cols: HashMap<Colour, Match> = HashMap::new();
+    img_2_cols.iter().for_each(|c| {
+        info!("Matching colour {}", encode_hex(&c));
+        if let Some(col) = closest_colour(c, &img_1_cols) {
+            output_cols.insert(*c, col);
+        }
+    });
+
+    output_cols
+}
diff --git a/src/main.rs b/src/main.rs
index 79ad5ed..3a7120b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,95 +1,27 @@
 mod cli;
+mod colours;
 
 use clap::Parser;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 
 use dotenv::dotenv;
-use image::{DynamicImage, GenericImageView, Rgb};
 
 use crate::cli::Cli;
-
-// TODO (medium priority): replace hashset with another hashmap<u8, Vec<(u32, u32)>>;
-// that way we can track pixel locations for colours.
-type ColourSet = HashMap<u8, HashMap<u8, HashSet<u8>>>;
-type Colour = Rgb<u8>;
-
-fn extract_colours(img: DynamicImage) -> ColourSet {
-    let mut out: ColourSet = HashMap::new();
-    for (_x, _y, p) in img.pixels() {
-        out.entry(p[0])
-            .or_insert_with(HashMap::new)
-            .entry(p[1])
-            .or_insert_with(HashSet::new)
-            .insert(p[2]);
-    }
-    out
-}
-
-fn extract_colours_set(img: DynamicImage) -> HashSet<Rgb<u8>> {
-    let mut out = HashSet::new();
-    img.pixels().for_each(|(_x, _y, p)| {
-        out.insert(p);
-    });
-    out.into_iter().map(|c| Rgb([c[0], c[1], c[2]])).collect()
-}
-
-fn closest_colour(colour: &Colour, all: &ColourSet) -> Option<Colour> {
-    // use redmean to calculate the distance between colours
-    let mut closest: Option<Colour> = None;
-    let mut dist: f32 = f32::MAX;
-
-    let (colour_r, colour_g, colour_b) = (colour[0] as f32, colour[1] as f32, colour[2] as f32);
-    for (r, gbs) in all.iter() {
-        let r_bar = 0.5 * (*r as f32 + colour_r);
-        let r_squared = (*r as f32 - colour_r) * (*r as f32 - colour_r);
-        for (g, bs) in gbs.iter() {
-            let g_squared = (*g as f32 - colour_g) * (*g as f32 - colour_g);
-            for b in bs {
-                let b_squared = (*b as f32 - colour_b) * (*b as f32 - colour_b);
-                let delta = (2.0 + r_bar / 256.0) * r_squared
-                    + 4.0 * g_squared
-                    + (2.0 + (255.0 - r_bar) / 256.0) * b_squared;
-                if delta < dist {
-                    dist = delta;
-                    closest = Some(Rgb([*r, *g, *b]));
-                }
-            }
-        }
-    }
-    return closest;
-}
-
-fn map_image_list(all_cols: &ColourSet, cols: Vec<Colour>) -> HashMap<Colour, Colour> {
-    let mut output_cols: HashMap<Colour, Colour> = HashMap::new();
-
-    for c in cols {
-        if let Some(col) = closest_colour(&c, &all_cols) {
-            output_cols.insert(c, col);
-        }
-    }
-    output_cols
-}
-
-fn map_image_image(img_1_cols: &ColourSet, img_2: DynamicImage) -> HashMap<Colour, Colour> {
-    let img_2_cols = extract_colours_set(img_2);
-
-    let mut output_cols: HashMap<Colour, Colour> = HashMap::new();
-    img_2_cols.iter().for_each(|c| {
-        if let Some(col) = closest_colour(c, &img_1_cols) {
-            output_cols.insert(*c, col);
-        }
-    });
-
-    output_cols
-}
+use crate::colours::{Colour, Match, extract_colours, map_image_image, map_image_list};
 
 fn encode_hex(c: &Colour) -> String {
     format!("#{:02x}{:02x}{:02x}", c[0], c[1], c[2])
 }
 
-fn pretty_print(h: HashMap<Colour, Colour>) {
-    h.iter()
-        .for_each(|(k, v)| println!("{}: {}", encode_hex(k), encode_hex(v)))
+fn pretty_print(h: HashMap<Colour, Match>) {
+    h.iter().for_each(|(k, v)| {
+        println!(
+            "{}: {} ({:?})",
+            encode_hex(k),
+            encode_hex(&v.colour),
+            v.positions
+        )
+    })
 }
 
 fn main() {