diff --git a/src/main.rs b/src/main.rs
index 96f6a4a..c95ae14 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -4,17 +4,19 @@ use std::time::Duration;
 use anyhow::Context;
 
 use chrono::{NaiveDateTime, Utc};
-use image::{GenericImageView, Pixel};
+use image::{DynamicImage, GenericImageView, Pixel};
 use log::{debug, error, info};
 
 /// Folder the camera images are uploaded to
 const FOLDER_WITH_NEW_IMAGES: &str = "/dev/shm/camera";
+//const FOLDER_WITH_NEW_IMAGES: &str = "/tmp/camera";
 
 /// File created in the uploads directory when the upload finishes.
 const COMMIT_FILENAME : &str = "commit";
 
 /// Folder where the cropped bird pics are saved
 const FOLDER_WITH_BIRD_IMAGES: &str = "/backup/krmitko";
+//const FOLDER_WITH_BIRD_IMAGES: &str = "/tmp/ptaci";
 
 /// Image cropping config: left top X
 const CROP_X : u32 = 1872;
@@ -47,7 +49,7 @@ fn main() {
     loop {
         if !commit_file.exists() {
             debug!("No commit file, wait.");
-            std::thread::sleep(Duration::from_secs(10));
+            std::thread::sleep(Duration::from_secs(5));
             continue;
         }
 
@@ -55,7 +57,16 @@ fn main() {
             error!("Error processing pics: {e}");
         }
 
-        let _ = std::fs::remove_dir_all(FOLDER_WITH_NEW_IMAGES);
+        // clean up. The assumption is that the bird processing is much faster than photo capture,
+        // so we dont need to be super careful with the timing
+        if let Ok(paths) = std::fs::read_dir(FOLDER_WITH_NEW_IMAGES) {
+            for dir_entry in paths {
+                let Ok(dir_entry) = dir_entry else { continue; };
+                if dir_entry.path().is_file() {
+                    let _ = std::fs::remove_file(dir_entry.path());
+                }
+            }
+        }
     }
 }
 
@@ -64,9 +75,16 @@ fn process_camera_pics() -> anyhow::Result<()> {
 
     let paths = std::fs::read_dir(FOLDER_WITH_NEW_IMAGES).context("Read folder with images")?;
 
-    let mut crops = vec![];
-    let mut thumbs = vec![];
-    let mut timestamps = vec![];
+
+    struct Pic {
+        crop: DynamicImage,
+        // the actual thumb is sized to fit here, it can be a bit smaller
+        thumb: [u8; THUMB_H * THUMB_W],
+        timestamp: i64,
+        filename: String,
+    }
+
+    let mut pics = vec![];
 
     info!("Loading files");
     for dir_entry in paths {
@@ -78,32 +96,38 @@ fn process_camera_pics() -> anyhow::Result<()> {
 
         debug!("{}", dir_entry.path().display());
 
+        // load the pic as is
         let Ok(img) = image::open(dir_entry.path()) else {
             continue;
         };
 
-        // File loaded fine, assume it's OK
-        timestamps.push(meta.ctime());
-
+        // extract the interesting rectangle
         let crop = img.crop_imm(CROP_X, CROP_Y, CROP_W, CROP_H);
+
+        // resize for change detection. This is a very small bitmap
         let thumb = crop.thumbnail(THUMB_W as u32, THUMB_H as u32);
 
-        crops.push(crop);
+        let mut pic = Pic {
+            crop,
+            thumb: [0u8; THUMB_H * THUMB_W],
+            timestamp: meta.ctime(),
+            filename: dir_entry.path().file_name().unwrap_or_default()
+                .to_string_lossy().to_string(),
+        };
 
-        let mut thumb_ar = [0u8; THUMB_H * THUMB_W];
-        for y in 0..thumb.height() {
-            for x in 0..thumb.width() {
-                thumb_ar[(y * thumb.width() + x) as usize] = thumb.get_pixel(x, y).to_luma().0[0];
-            }
+        // extract all pixels
+        for (x, y, val) in thumb.pixels() {
+            pic.thumb[(y * thumb.width() + x) as usize] = val.to_luma().0[0];
         }
 
-        thumbs.push(thumb_ar);
+        pics.push(pic);
     }
 
     info!("Computing digests & medians");
+    // transpose the thumb vecs so we can compute medians
     let mut transposed = vec![];
-    for thumb in thumbs.iter() {
-        for (b, item) in thumb.iter().enumerate() {
+    for pic in &pics {
+        for (b, item) in pic.thumb.iter().enumerate() {
             if transposed.len() <= b {
                 transposed.push(vec![]);
             }
@@ -111,25 +135,26 @@ fn process_camera_pics() -> anyhow::Result<()> {
         }
     }
 
+    // compute medians
     let mut medians = [0; THUMB_H * THUMB_W];
-
-    for (a, column) in transposed.iter().enumerate() {
+    for (a, mut column) in transposed.into_iter().enumerate() {
+        column.sort();
         medians[a] = column[column.len() / 2]; // approximately median ...
     }
 
     debug!("Medians: {:?}", medians);
 
     info!("Finding deviations");
-    for (thumb_num, thumb) in thumbs.iter().enumerate() {
-        let deviation = thumb.iter().zip(medians.iter())
+    for pic in pics {
+        let deviation = pic.thumb.iter().zip(medians.iter())
             .map(|(a, b)| (*a as i16 - *b as i16).abs() as u32).fold(0u32, |a, b| a + b);
 
-        debug!("Thumb {thumb_num} summary diff from median is: {deviation}");
+        debug!("Picture {} summary diff from median is: {deviation}", pic.filename);
 
         if deviation > THRESHOLD_DEVIATION {
-            info!("LIKELY BIRD!!!! in picture #{thumb_num}");
+            info!("LIKELY BIRD!!!! in picture {}", pic.filename);
 
-            let datetime_str = parse_unix_ts(timestamps[thumb_num]).format("%Y-%m-%d_%H-%M-%S");
+            let datetime_str = parse_unix_ts(pic.timestamp).format("%Y-%m-%d_%H-%M-%S");
             let path = format!("{}/{}.jpg", FOLDER_WITH_BIRD_IMAGES, datetime_str);
             let mut pb = PathBuf::from(path);
 
@@ -141,7 +166,7 @@ fn process_camera_pics() -> anyhow::Result<()> {
                 cnt += 1;
             }
 
-            if let Err(e) = crops[thumb_num].save(pb) {
+            if let Err(e) = pic.crop.save(pb) {
                 error!("Fail to save pic: {e}");
             }
         }