diff --git a/Cargo.toml b/Cargo.toml
index 69cd0ba..25eeb42 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,4 +16,8 @@ criterion = "0.5.1"
 
 [[bench]]
 name = "multithreading"
+harness = false
+
+[[bench]]
+name = "indexing"
 harness = false
\ No newline at end of file
diff --git a/benches/indexing.rs b/benches/indexing.rs
new file mode 100644
index 0000000..e5097f1
--- /dev/null
+++ b/benches/indexing.rs
@@ -0,0 +1,36 @@
+use std::path::Path;
+
+use criterion::Criterion;
+use criterion::{black_box, criterion_group, criterion_main};
+use imsearch::search_index::{Database, FeatureGenerator};
+
+pub fn bench_images(c: &mut Criterion) {
+    c.bench_function("indexing images", |b| {
+        b.iter(|| {
+            let files: Vec<std::path::PathBuf> = std::fs::read_dir("res/benchmark/")
+                .unwrap()
+                .map(|f| f.unwrap().path())
+                .collect();
+
+            let feats: Vec<FeatureGenerator> = vec![
+                imsearch::feature::luminance_distribution,
+                imsearch::feature::color_distribution,
+                imsearch::feature::average_luminance,
+                imsearch::feature::aspect_ratio,
+            ];
+
+            let db = Database::new(&files, feats).unwrap();
+
+            black_box(
+                db.search(
+                    Path::new("res/benchmark/bird.png"),
+                    imsearch::feature::luminance_distribution,
+                )
+                .unwrap(),
+            );
+        })
+    });
+}
+
+criterion_group!(benches, bench_images);
+criterion_main!(benches);
diff --git a/res/benchmark/backlit_flower.png b/res/benchmark/backlit_flower.png
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diff --git a/res/benchmark/bird.png b/res/benchmark/bird.png
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diff --git a/res/benchmark/daisy_reddish_2.png b/res/benchmark/daisy_reddish_2.png
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diff --git a/res/benchmark/flower_hover.png b/res/benchmark/flower_hover.png
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diff --git a/res/benchmark/flower_purple_1.png b/res/benchmark/flower_purple_1.png
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diff --git a/res/benchmark/flower_yellow.png b/res/benchmark/flower_yellow.png
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diff --git a/res/benchmark/flowers_gray.png b/res/benchmark/flowers_gray.png
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diff --git a/res/benchmark/hut.png b/res/benchmark/hut.png
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diff --git a/res/benchmark/ice_flower.png b/res/benchmark/ice_flower.png
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diff --git a/res/benchmark/lago_como_1.png b/res/benchmark/lago_como_1.png
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diff --git a/res/benchmark/mushroom.png b/res/benchmark/mushroom.png
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diff --git a/res/benchmark/plant_green.png b/res/benchmark/plant_green.png
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diff --git a/res/benchmark/sunset_tree.png b/res/benchmark/sunset_tree.png
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diff --git a/res/benchmark/town_blue.png b/res/benchmark/town_blue.png
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diff --git a/src/Feature/mod.rs b/src/Feature/mod.rs
deleted file mode 100644
index 9507bce..0000000
--- a/src/Feature/mod.rs
+++ /dev/null
@@ -1,106 +0,0 @@
-use std::sync::Arc;
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-enum FeatureResult {
-    /// A boolean. Just a boolean
-    Bool(bool),
-    /// Signed 32-bit integer
-    I32(i32),
-    /// 32-bit single precision floating point
-    /// can be used for aspect ratio or luminance
-    F32(f32),
-    /// Vector for nested multidimensional 
-    Vec(Vec<FeatureResult>),
-    /// Standard RGBA color 
-    RGBA(f32, f32, f32, f32),
-    /// Indices intended for the usage in historgrams
-    Indices(Vec<u64>)
-}
-
-impl Default for FeatureResult {
-    fn default() -> Self {
-        FeatureResult::Bool(false)
-    }
-}
-
-/// For some feature return type we want to implement a custom compare function
-/// for example: historgrams are compared with cosine similarity
-impl PartialEq for FeatureResult {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Self::Bool(l0), Self::Bool(r0)) => l0 == r0,
-            (Self::I32(l0), Self::I32(r0)) => l0 == r0,
-            (Self::F32(l0), Self::F32(r0)) => l0 == r0,
-            (Self::Vec(l0), Self::Vec(r0)) => l0 == r0,
-            (Self::RGBA(l0, l1, l2, l3), Self::RGBA(r0, r1, r2, r3)) => l0 == r0 && l1 == r1 && l2 == r2 && l3 == r3,
-            (Self::Indices(_), Self::Indices(_)) => todo!("implement cosine similarity"),
-            _ => false,
-        }
-    }
-}
-
-type FeatureGenerator = Box<dyn Fn(crate::Arc<Image<f32>>) -> (String, FeatureResult)>;
-
-#[derive(Serialize, Deserialize, Default)]
-struct Database {
-    images: HashMap<String, HashMap<String, FeatureResult>>,
-
-    /// keep feature generator for the case when we add a new image
-    /// this field is not serialized and needs to be wrapped in an option
-    #[serde(skip)]
-    generators: Option<Vec<FeatureGenerator>>
-}
-
-impl Database {
-    
-    pub fn add_feature(&mut self, feature: FeatureGenerator) {
-        for (path, features) in self.images.iter_mut() {
-            // compute feature for every image
-            todo!("run this as a closure parallel with a thread pool");
-            let (name, res) = feature(todo!("load image from disk"));
-            features.insert(name, res);
-        }
-
-        if let Some(generators) = self.generators.as_mut() {
-            generators.push(feature);
-        } else {
-            self.generators = Some(vec![feature])
-        }
-    }
-
-    pub fn add_image(&mut self, path: String) {
-        let image = todo!("load image from disk");
-        let mut features = HashMap::new();
-        if let Some(generators) = self.generators {
-            for generator in generators.iter() {
-                let (name, res) = generator(image);
-                features.insert(name, res);
-            }
-        }
-        self.images.insert(path, features);
-    }
-}
-
-fn average_luminance(image: Arc<Image<f32>>) -> (String, FeatureResult) {
-    let num_pixels = image.pixels.len() as u32;
-    let total_brightness: f32 = image.pixels
-        .iter()
-        .map(|(r, g, b, _)| 0.299 * r + 0.587 * g + 0.114 * b) // Calculate Y for each pixel
-        .sum();
-    let average_brightness = total_brightness / num_pixels as f32;
-
-    let feature_name = String::from("average-brightness");
-    let feature_result = FeatureResult::F32(average_brightness);
-
-    (feature_name, feature_result)
-}
-fn compare_Dim(image0: Arc<Image<f32>>, image1: Arc<Image<f32>>) -> (String, FeatureResult) {
-    let a = image0.width as f32 / image0.height as f32;
-    let b = image1.width as f32 / image1.height as f32;
-    let equal = a == b;
-
-    let feature_name = String::from("Dimension-comparison");
-    let feature_result = FeatureResult::Bool(equal);
-
-    (feature_name, feature_result)
-}
diff --git a/src/feature/mod.rs b/src/feature/mod.rs
index b5bd2c9..4906ee1 100644
--- a/src/feature/mod.rs
+++ b/src/feature/mod.rs
@@ -8,34 +8,37 @@
 //! - aspect ratio of images computed a width/height
 //! All features are designed to used with sRGB color channels only.
 
-use std::sync::Arc;
 use crate::{image::Image, search_index::FeatureResult};
+use std::sync::Arc;
 
 #[allow(unused)]
 // from https://github.com/programmieren-mit-rust/pr-ferrisgroup/issues/8 by @SirTalksalot75
 /// Compute a basic distribution of values from all color channels and count their apprearances in buckets.
 /// This function will use 5 buckets per channel.
-fn color_distribution(image: Arc<Image<f32>>) -> (String, FeatureResult) {
+pub fn color_distribution(image: Arc<Image<f32>>) -> (String, FeatureResult) {
     const N: usize = 5;
 
     let mut histogram = vec![0u64; N * 3 + 1];
 
-    const INV_255: f32 = 1./255. * N as f32;
+    const INV_255: f32 = 1. / 255. * N as f32;
     for (r, g, b, _) in image.iter() {
         // map linear channel value to bin index
-        histogram[ (r * INV_255) as usize] += 1;
-        histogram[ (g * INV_255) as usize * 2 ] += 1;
-        histogram[ (b * INV_255) as usize * 3 ] += 1;
+        histogram[(r * INV_255) as usize] += 1;
+        histogram[(g * INV_255) as usize * 2] += 1;
+        histogram[(b * INV_255) as usize * 3] += 1;
     }
 
-    (String::from("luminance-distribution"), FeatureResult::Indices(histogram))
+    (
+        String::from("luminance-distribution"),
+        FeatureResult::Indices(histogram),
+    )
 }
 
 #[allow(unused)]
 // from https://github.com/programmieren-mit-rust/pr-ferrisgroup/issues/8 by @SirTalksalot75
 /// Compute a basic distribution of luminance values and count their apprearances in buckets.
 /// Luminance is calculated via Digital ITU BT.601 and NOT the more common Photometric ITU BT.709
-fn luminance_distribution(image: Arc<Image<f32>>) -> (String, FeatureResult) {
+pub fn luminance_distribution(image: Arc<Image<f32>>) -> (String, FeatureResult) {
     let mut histogram = vec![0u64; 256]; // Assuming 256 bins for the histogram
 
     for (r, g, b, _) in image.iter() {
@@ -44,15 +47,18 @@ fn luminance_distribution(image: Arc<Image<f32>>) -> (String, FeatureResult) {
         let luminance = (0.299 * r + 0.587 * g + 0.114 * b) as usize;
         histogram[luminance] += 1;
     }
-    
-    (String::from("luminance-distribution"), FeatureResult::Indices(histogram))
+
+    (
+        String::from("luminance-distribution"),
+        FeatureResult::Indices(histogram),
+    )
 }
 
 #[allow(unused)]
 // from https://github.com/programmieren-mit-rust/pr-ferrisgroup/issues/8 by @SirTalksalot75
 /// Compute the average luminance of all pixels in a given image.
 /// Luminance is calculated via Digital ITU BT.601 and NOT the more common Photometric ITU BT.709
-fn average_luminance(image: Arc<Image<f32>>) -> (String, FeatureResult) {
+pub fn average_luminance(image: Arc<Image<f32>>) -> (String, FeatureResult) {
     let num_pixels = image.pixels().len() as u32;
     let total_brightness: f32 = image
         .iter()
@@ -68,7 +74,7 @@ fn average_luminance(image: Arc<Image<f32>>) -> (String, FeatureResult) {
 
 #[allow(unused)]
 // from https://github.com/programmieren-mit-rust/pr-ferrisgroup/issues/8 by @SirTalksalot75
-fn aspect_ratio(image: Arc<Image<f32>>) -> (String, FeatureResult) {
+pub fn aspect_ratio(image: Arc<Image<f32>>) -> (String, FeatureResult) {
     let a = image.width() as f32 / image.height() as f32;
 
     (String::from("aspect-ratio"), FeatureResult::Percent(a))
@@ -93,7 +99,13 @@ mod test {
 
         let db = Database::new(&files, feats).unwrap();
 
-        for (path, sim) in db.search(Path::new("res/integration/gray_image.png"), color_distribution).unwrap() {
+        for (path, sim) in db
+            .search(
+                Path::new("res/integration/gray_image.png"),
+                color_distribution,
+            )
+            .unwrap()
+        {
             let file_name = path.file_name().unwrap().to_str().unwrap();
             if file_name.eq("gray_image.png") {
                 assert_eq!(sim, 1.);
@@ -113,7 +125,13 @@ mod test {
 
         let db = Database::new(&files, feats).unwrap();
 
-        for (path, sim) in db.search(Path::new("res/integration/gray_image.png"), average_luminance).unwrap() {
+        for (path, sim) in db
+            .search(
+                Path::new("res/integration/gray_image.png"),
+                average_luminance,
+            )
+            .unwrap()
+        {
             let file_name = path.file_name().unwrap().to_str().unwrap();
             if file_name.eq("gray_image.png") {
                 assert_eq!(sim, 1.);
@@ -133,7 +151,10 @@ mod test {
 
         let db = Database::new(&files, feats).unwrap();
 
-        for (path, sim) in db.search(Path::new("res/integration/gray_image.png"), aspect_ratio).unwrap() {
+        for (path, sim) in db
+            .search(Path::new("res/integration/gray_image.png"), aspect_ratio)
+            .unwrap()
+        {
             let file_name = path.file_name().unwrap().to_str().unwrap();
             if file_name.eq("gray_image.png") {
                 assert_eq!(sim, 1.);
@@ -141,4 +162,4 @@ mod test {
             println!("{} {}", file_name, sim);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/lib.rs b/src/lib.rs
index 2532a15..d086197 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,19 +7,18 @@
 //! .unwrap()
 //! .map(|f| f.unwrap().path())
 //! .collect();
-//! 
+//!
 //! let feats: Vec<FeatureGenerator> = vec![average_rgb_value];
-//! 
+//!
 //! let db = Database::new(&files, feats).unwrap();
-//! 
+//!
 //! db.write_to_file(json);
-//! ``` 
+//! ```
 
 extern crate core;
 
+pub mod feature;
 pub mod image;
 pub mod image_loader;
 pub mod multithreading;
 pub mod search_index;
-pub mod feature;
-