diff --git a/src/__main__.py b/src/__main__.py
index 6d0a797..14e4052 100644
--- a/src/__main__.py
+++ b/src/__main__.py
@@ -2,10 +2,9 @@ import argparse
 import logging
 import os
 import sys
-import time
-from concurrent.futures import ProcessPoolExecutor
 
-from .files import Directory, FileGroup, FileImgMimetype, FileSizeRange
+from .files import Directory, FileImgMimetype, FileSizeRange
+from .optimizer import ImgOptimizer
 
 DEFAULT_DEST_DIR = "data"
 
@@ -109,32 +108,12 @@ def main():
         nb_workers,
     )
 
-    start = time.perf_counter()
+    optimizer = ImgOptimizer(dest_dir, args.workers)
+    result = optimizer.optimize(fg)
+    (optimized, percent, size) = result.stats()
 
-    with ProcessPoolExecutor(nb_workers) as p:
-        futures = [p.submit(f.opti, dest_dir) for f in fg.get_files()]
-
-    fg_opti = FileGroup()
-    optimized = 0
-    for f in futures:
-        if (res := f.result()) and res is not None:
-            match res:
-                case (orig, None):
-                    logging.debug(f"no optimization for file: {orig}")
-                    fg_opti.add(orig)
-                case (orig, opti):
-                    optimized += 1
-                    logging.debug(
-                        f"optimization for file: {orig} -> {(1 - (opti.size / orig.size)) * 100:.2f}%"  # noqa
-                    )
-                    fg_opti.add(opti)
-
-    logging.info(f"optimization finished in {time.perf_counter() - start:.2f}s")
-
-    percent = (1 - (fg_opti._size / fg._size)) * 100
-    size_gained = fg._size - fg_opti._size
     logging.info(
-        f"total optimization ({optimized}/{len(fg)}): {percent:.2f}% -> {size_gained:.2f} Mb"  # noqa
+        f"total optimization ({optimized}/{len(result.orig)}): {percent:.2f}% -> {size:.2f} Mb"  # noqa
     )
 
 
diff --git a/src/optimizer.py b/src/optimizer.py
new file mode 100644
index 0000000..d13eaec
--- /dev/null
+++ b/src/optimizer.py
@@ -0,0 +1,88 @@
+import logging
+import os
+import subprocess
+import time
+from concurrent.futures import ProcessPoolExecutor
+from dataclasses import dataclass
+from typing import Optional
+
+from .files import File, FileGroup, FileImgMimetype
+
+
+@dataclass(slots=True, frozen=True)
+class OptimizerResult:
+    orig: FileGroup
+    opti: FileGroup
+    optimized: int
+
+    def stats(self) -> tuple[int, float, float]:
+        percent = (1 - (self.opti._size / self.orig._size)) * 100
+        size = self.orig._size - self.opti._size
+        return (self.optimized, percent, size)
+
+
+@dataclass(slots=True, frozen=True)
+class ImgOptimizer:
+    dest_dir: str
+    nb_workers: int = 5
+
+    def _jpeg_optim(self, file: File) -> tuple["File", Optional["File"]] | None:
+        # remove ".." avoiding treat file in same dir
+        filepath = "/".join(file.path.split("/")[:-1])
+        if filepath.startswith(".."):
+            filepath = filepath.lstrip("..")
+
+        # replace all spaces in dir name for readability
+        dest_dir = os.path.join(self.dest_dir, filepath.lstrip("/")).replace(" ", "_")
+        os.makedirs(dest_dir, exist_ok=True)
+
+        # use "-S <i>k" to set maximum size in kilobytes
+        cmd = f"jpegoptim -s -p -q -S 1024k '{file.path}' -d {dest_dir}"
+        logging.debug("optimization launched for file: %s -> %s", self, cmd)
+        try:
+            _ = subprocess.run(cmd, shell=True, check=True)
+        except subprocess.CalledProcessError as e:
+            logging.error("error while running command: %s, err: %s", cmd, e.output)
+            return None
+        except Exception:
+            logging.error(
+                "unexpected error while running command: %s", cmd, exc_info=True
+            )
+            return None
+
+        try:
+            file_optim = File.from_directory(dest_dir, file.name)
+        except Exception as e:
+            logging.debug("unable to get file: %s after optimization: %s", file, e)
+            return file, None
+
+        return file, file_optim
+
+    def _optim(self, file: File) -> tuple["File", Optional["File"]] | None:
+        if file.mimetype == FileImgMimetype.JPEG.value:
+            return self._jpeg_optim(file)
+        return None
+
+    def optimize(self, file_group: FileGroup) -> OptimizerResult:
+        start = time.perf_counter()
+
+        with ProcessPoolExecutor(self.nb_workers) as p:
+            futures = [p.submit(self._optim, f) for f in file_group.get_files()]
+
+        file_group_optim = FileGroup()
+        optimized = 0
+        for f in futures:
+            if (res := f.result()) and res is not None:
+                match res:
+                    case (orig, None):
+                        logging.debug(f"no optimization for file: {orig}")
+                        file_group_optim.add(orig)
+                    case (orig, opti):
+                        optimized += 1
+                        logging.debug(
+                            f"optimization for file: {orig} -> {(1 - (opti.size / orig.size)) * 100:.2f}%"  # noqa
+                        )
+                        file_group_optim.add(opti)
+
+        logging.info(f"optimization finished in {time.perf_counter() - start:.2f}s")
+        return OptimizerResult(file_group, file_group_optim, optimized)