diff --git a/src/buffer.rs b/src/buffer.rs
index 2555248..f44f953 100644
--- a/src/buffer.rs
+++ b/src/buffer.rs
@@ -11,7 +11,7 @@ impl Buf {
     }
 
     // Truncate x and y and return a corresponding index into the data slice.
-    fn index(&self, x: f32, y: f32) -> usize {
+    const fn index(&self, x: f32, y: f32) -> usize {
         // x/y can come in negative, hence we shift them by width/height.
         let i = (x + self.width as f32) as usize & (self.width - 1);
         let j = (y + self.height as f32) as usize & (self.height - 1);
diff --git a/src/imgdata.rs b/src/imgdata.rs
index c41d03c..bc9d2b2 100644
--- a/src/imgdata.rs
+++ b/src/imgdata.rs
@@ -1,5 +1,6 @@
 use crate::{grid::Grid, palette::Palette};
 
+use image::RgbImage;
 use itertools::multizip;
 
 /// Stores data that is located in grids that is used for image generation
@@ -48,16 +49,6 @@ impl ThinGridData {
             .select_nth_unstable_by(index, |a, b| a.partial_cmp(b).unwrap());
         sorted[index]
     }
-
-    pub fn size_of(&self) -> usize {
-        let mut output: usize = 0;
-        output += std::mem::size_of_val(&self.width);
-        output += std::mem::size_of_val(&self.height);
-        for i in self.data.iter() {
-            output += std::mem::size_of_val(&i);
-        }
-        output
-    }
 }
 
 /// Class for storing data that will be used to create images
@@ -65,29 +56,17 @@ impl ThinGridData {
 pub struct ImgData {
     pub grids: Vec<ThinGridData>,
     pub palette: Palette,
-    pub iteration: i32,
 }
 
 impl ImgData {
-    pub fn new(in_grids: Vec<ThinGridData>, in_palette: Palette, in_iteration: i32) -> Self {
+    pub fn new(in_grids: Vec<ThinGridData>, in_palette: Palette) -> Self {
         ImgData {
             grids: in_grids,
             palette: in_palette,
-            iteration: in_iteration,
         }
     }
 
-    pub fn size_of(&self) -> usize {
-        let mut output: usize = 0;
-        output += std::mem::size_of_val(&self.iteration);
-        output += std::mem::size_of_val(&self.palette);
-        for grid in self.grids.iter() {
-            output += grid.size_of();
-        }
-        output
-    }
-
-    pub fn save_to_image(&self) {
+    pub fn to_image(&self) -> RgbImage {
         let (width, height) = (self.grids[0].width, self.grids[0].height);
         let mut img = image::RgbImage::new(width as u32, height as u32);
 
@@ -116,8 +95,6 @@ impl ImgData {
                 img.put_pixel(x as u32, y as u32, image::Rgb([r as u8, g as u8, b as u8]));
             }
         }
-
-        img.save(format!("./tmp/out_{}.png", self.iteration).as_str())
-            .unwrap();
+        img
     }
 }
diff --git a/src/model.rs b/src/model.rs
index 9505ac9..50d3a9d 100644
--- a/src/model.rs
+++ b/src/model.rs
@@ -23,13 +23,13 @@ pub struct Model {
     diffusivity: usize,
 
     // Current model iteration.
-    iteration: i32,
+    iteration: usize,
 
     // Color palette
     palette: Palette,
 
     // List of ImgData to be processed post-simulation into images
-    img_data_vec: Vec<ImgData>,
+    img_data_vec: Vec<(usize, ImgData)>,
 }
 
 impl Model {
@@ -143,15 +143,11 @@ impl Model {
         );
     }
 
-    fn size_of_imgdata_vec(&self) -> usize {
-        self.img_data_vec[0].size_of() * self.img_data_vec.len()
-    }
-
     fn save_image_data(&mut self) {
         let grids = ThinGridData::new_from_grid_vec(self.grids.clone());
-        let img_data = ImgData::new(grids, self.palette, self.iteration);
-        self.img_data_vec.push(img_data);
-        let size: usize = self.size_of_imgdata_vec();
+        let img_data = ImgData::new(grids, self.palette);
+        self.img_data_vec.push((self.iteration + 1, img_data));
+        let size: usize = std::mem::size_of_val(&self.img_data_vec);
         let mb = size / 1024 / 1024;
         // println!("{} B | {} KB | {} MB", size, size/1024, size/1024/1024);
 
@@ -171,7 +167,7 @@ impl Model {
         self.img_data_vec.clear();
     }
 
-    pub fn render_all_imgdata(&self) {
+    pub fn render_all_imgdata(&mut self) {
         if !Path::new("./tmp").exists() {
             std::fs::create_dir("./tmp").expect("could create directory");
         }
@@ -181,56 +177,15 @@ impl Model {
             "{spinner:.green} [{elapsed_precise}] [{bar:40.cyan/blue}] ({pos}/{len}, {percent}%, {per_sec})",
         ));
 
-        /*
-        for img in &self.img_data_vec {
-            Self::save_to_image(img.to_owned());
-            pb.inc(1);
-        }
-        pb.finish();
-        */
-
         self.img_data_vec
+            .drain(..)
+            .collect::<Vec<_>>()
             .par_iter()
             .progress_with(pb)
-            .for_each(|img| {
-                // Self::save_to_image(img.to_owned());
-                img.save_to_image();
+            .for_each(|(i, img)| {
+                img.to_image()
+                    .save(format!("./tmp/out_{}.png", i).as_str())
+                    .unwrap();
             });
     }
-
-    /*
-    pub fn save_to_image(imgdata: ImgData) {
-        let (width, height) = (imgdata.grids[0].width, imgdata.grids[0].height);
-        let mut img = image::RgbImage::new(width as u32, height as u32);
-
-        let max_values: Vec<_> = imgdata
-            .grids
-            .iter()
-            .map(|grid| grid.quantile(0.999) * 1.5)
-            .collect();
-
-        for y in 0..height {
-            for x in 0..width {
-                let i = y * width + x;
-                let (mut r, mut g, mut b) = (0.0_f32, 0.0_f32, 0.0_f32);
-                for (grid, max_value, color) in
-                    multizip((&imgdata.grids, &max_values, &imgdata.palette.colors))
-                {
-                    let mut t = (grid.data()[i] / max_value).clamp(0.0, 1.0);
-                    t = t.powf(1.0 / 2.2); // gamma correction
-                    r += color.0[0] as f32 * t;
-                    g += color.0[1] as f32 * t;
-                    b += color.0[2] as f32 * t;
-                }
-                r = r.clamp(0.0, 255.0);
-                g = g.clamp(0.0, 255.0);
-                b = b.clamp(0.0, 255.0);
-                img.put_pixel(x as u32, y as u32, image::Rgb([r as u8, g as u8, b as u8]));
-            }
-        }
-
-        img.save(format!("./tmp/out_{}.png", imgdata.iteration).as_str())
-            .unwrap();
-    }
-    */
 }