diff --git a/app/scodoc/sco_logos.py b/app/scodoc/sco_logos.py
index 0737e7f03..dba5dc61e 100644
--- a/app/scodoc/sco_logos.py
+++ b/app/scodoc/sco_logos.py
@@ -137,8 +137,6 @@ class Logo:
         self.logoname = secure_filename(logoname)
         self.scodoc_dept_id = dept_id
         self.prefix = prefix or ""
-        self.suffix = None
-        self.dimensions = None
         if self.scodoc_dept_id:
             self.dirpath = os.path.sep.join(
                 [
@@ -151,8 +149,16 @@ class Logo:
         self.basepath = os.path.sep.join(
             [self.dirpath, self.prefix + secure_filename(self.logoname)]
         )
-        self.filepath = None
-        self.filename = None
+        # next attributes are computer by the select function
+        self.suffix = "Not inited: call the select or create function before access"
+        self.filepath = "Not inited: call the select or create function before access"
+        self.filename = "Not inited: call the select or create function before access"
+        self.size = "Not inited: call the select or create function before access"
+        self.aspect_ratio = (
+            "Not inited: call the select or create function before access"
+        )
+        self.density = "Not inited: call the select or create function before access"
+        self.cm = "Not inited: call the select or create function before access"
 
     def _set_format(self, fmt):
         self.suffix = fmt
@@ -182,6 +188,31 @@ class Logo:
             except IOError:
                 pass
 
+    def _read_info(self, img):
+        """computes some properties from the real image
+        aspect_ratio assumes that x_density and y_density are equals
+        """
+        x_size, y_size = img.size
+        self.density = img.info.get("dpi", None)
+        unit = 1
+        if self.density is None:  # no dpi found try jfif infos
+            self.density = img.info.get("jfif_density", None)
+            unit = img.info.get("jfif_unit", 0)  # 0 = no unit ; 1 = inch ; 2 = cm
+        if self.density is not None:
+            x_density, y_density = self.density
+            if unit != 0:
+                unit2cm = [0, 1 / 2.54, 1][unit]
+                x_cm = round(x_size * unit2cm / x_density, 2)
+                y_cm = round(y_size * unit2cm / y_density, 2)
+                self.cm = (x_cm, y_cm)
+            else:
+                self.cm = None
+        else:
+            self.cm = None
+
+        self.size = (x_size, y_size)
+        self.aspect_ratio = float(x_size) / y_size
+
     def select(self):
         """
         Récupération des données pour un logo existant
@@ -195,7 +226,7 @@ class Logo:
                 self._set_format(suffix)
                 with open(self.filepath, "rb") as f:
                     img = PILImage.open(f)
-                    self.dimensions = img.size
+                    self._read_info(img)
                 return self
         return None
 
diff --git a/tests/ressources/test_logos/logo_A.jpg b/tests/ressources/test_logos/logo_A.jpg
new file mode 100644
index 000000000..7f107a05b
Binary files /dev/null and b/tests/ressources/test_logos/logo_A.jpg differ
diff --git a/tests/ressources/test_logos/logo_C.jpg b/tests/ressources/test_logos/logo_C.jpg
new file mode 100644
index 000000000..bdca2b736
Binary files /dev/null and b/tests/ressources/test_logos/logo_C.jpg differ
diff --git a/tests/ressources/test_logos/logo_D.png b/tests/ressources/test_logos/logo_D.png
new file mode 100644
index 000000000..7ac56e168
Binary files /dev/null and b/tests/ressources/test_logos/logo_D.png differ
diff --git a/tests/ressources/test_logos/logo_E.jpg b/tests/ressources/test_logos/logo_E.jpg
new file mode 100644
index 000000000..e97b78d07
Binary files /dev/null and b/tests/ressources/test_logos/logo_E.jpg differ
diff --git a/tests/ressources/test_logos/logo_F.jpeg b/tests/ressources/test_logos/logo_F.jpeg
new file mode 100644
index 000000000..c3750e29f
Binary files /dev/null and b/tests/ressources/test_logos/logo_F.jpeg differ
diff --git a/tests/ressources/test_logos/logos_1/logo_A.jpg b/tests/ressources/test_logos/logos_1/logo_A.jpg
new file mode 100644
index 000000000..96cfabd5e
Binary files /dev/null and b/tests/ressources/test_logos/logos_1/logo_A.jpg differ
diff --git a/tests/ressources/test_logos/logos_1/logo_B.jpg b/tests/ressources/test_logos/logos_1/logo_B.jpg
new file mode 100644
index 000000000..2ebb82823
Binary files /dev/null and b/tests/ressources/test_logos/logos_1/logo_B.jpg differ
diff --git a/tests/ressources/test_logos/logos_2/logo_A.jpg b/tests/ressources/test_logos/logos_2/logo_A.jpg
new file mode 100644
index 000000000..8c1c4efcb
Binary files /dev/null and b/tests/ressources/test_logos/logos_2/logo_A.jpg differ
diff --git a/tests/unit/test_logos.py b/tests/unit/test_logos.py
new file mode 100644
index 000000000..8cf2e275b
--- /dev/null
+++ b/tests/unit/test_logos.py
@@ -0,0 +1,183 @@
+# -*- coding: utf-8 -*-
+
+"""Test Logos
+
+
+Utiliser comme: 
+    pytest tests/unit/test_logos.py
+
+"""
+from io import BytesIO
+from pathlib import Path
+from shutil import copytree, copy, rmtree
+
+import pytest as pytest
+from _pytest.python_api import approx
+
+import app
+from app import db
+from app.models import Departement
+import app.scodoc.sco_utils as scu
+from app.scodoc.sco_logos import find_logo, Logo, list_logos
+
+RESOURCES_DIR = "/opt/scodoc/tests/ressources/test_logos"
+
+
+@pytest.fixture
+def create_dept(test_client):
+    """Crée 2 départements:
+    return departements object
+    """
+    dept1 = Departement(acronym="RT")
+    dept2 = Departement(acronym="INFO")
+    db.session.add(dept1)
+    db.session.add(dept2)
+    db.session.commit()
+    yield dept1, dept2
+    db.session.delete(dept1)
+    db.session.delete(dept2)
+    db.session.commit()
+
+
+@pytest.fixture
+def create_logos(create_dept):
+    """Crée les logos:
+    ...logos --+-- logo_A.jpg
+               +-- logo_C.jpg
+               +-- logo_D.png
+               +-- logo_E.jpg
+               +-- logo_F.jpeg
+               +-- logos_{d1} --+-- logo_A.jpg
+               |                +-- logo_B.jpg
+               +-- logos_{d2} --+-- logo_A.jpg
+
+    """
+    dept1, dept2 = create_dept
+    d1 = dept1.id
+    d2 = dept2.id
+    FILE_LIST = ["logo_A.jpg", "logo_C.jpg", "logo_D.png", "logo_E.jpg", "logo_F.jpeg"]
+    for fn in FILE_LIST:
+        from_path = Path(RESOURCES_DIR).joinpath(fn)
+        to_path = Path(scu.SCODOC_LOGOS_DIR).joinpath(fn)
+        copy(from_path.absolute(), to_path.absolute())
+    copytree(
+        f"{RESOURCES_DIR}/logos_1",
+        f"{scu.SCODOC_LOGOS_DIR}/logos_{d1}",
+    )
+    copytree(
+        f"{RESOURCES_DIR}/logos_2",
+        f"{scu.SCODOC_LOGOS_DIR}/logos_{d2}",
+    )
+    yield None
+    rmtree(f"{scu.SCODOC_LOGOS_DIR}/logos_{d1}")
+    rmtree(f"{scu.SCODOC_LOGOS_DIR}/logos_{d2}")
+    # rm files
+    for fn in FILE_LIST:
+        to_path = Path(scu.SCODOC_LOGOS_DIR).joinpath(fn)
+        to_path.unlink()
+
+
+def test_select_global_only(create_logos):
+    C_logo = app.scodoc.sco_logos.find_logo(logoname="C")
+    assert C_logo.filepath == f"{scu.SCODOC_LOGOS_DIR}/logo_C.jpg"
+
+
+def test_select_local_only(create_dept, create_logos):
+    dept1, dept2 = create_dept
+    B_logo = app.scodoc.sco_logos.find_logo(logoname="B", dept_id=dept1.id)
+    assert B_logo.filepath == f"{scu.SCODOC_LOGOS_DIR}/logos_{dept1.id}/logo_B.jpg"
+
+
+def test_select_local_override_global(create_dept, create_logos):
+    dept1, dept2 = create_dept
+    A1_logo = app.scodoc.sco_logos.find_logo(logoname="A", dept_id=dept1.id)
+    assert A1_logo.filepath == f"{scu.SCODOC_LOGOS_DIR}/logos_{dept1.id}/logo_A.jpg"
+
+
+def test_select_global_with_strict(create_dept, create_logos):
+    dept1, dept2 = create_dept
+    A_logo = app.scodoc.sco_logos.find_logo(logoname="A", dept_id=dept1.id, strict=True)
+    assert A_logo.filepath == f"{scu.SCODOC_LOGOS_DIR}/logos_{dept1.id}/logo_A.jpg"
+
+
+def test_looks_for_non_existant_should_give_none(create_dept, create_logos):
+    # search for a local non-existant logo returns None
+    dept1, dept2 = create_dept
+    no_logo = app.scodoc.sco_logos.find_logo(logoname="Z", dept_id=dept1.id)
+    assert no_logo is None
+
+
+def test_looks_localy_for_a_global_should_give_none(create_dept, create_logos):
+    # search for a local non-existant logo returns None
+    dept1, dept2 = create_dept
+    no_logo = app.scodoc.sco_logos.find_logo(
+        logoname="C", dept_id=dept1.id, strict=True
+    )
+    assert no_logo is None
+
+
+def test_get_jpg_data(create_dept, create_logos):
+    logo = find_logo("A", dept_id=None)
+    assert logo is not None
+    logo.select()
+    assert logo.logoname == "A"
+    assert logo.suffix == "jpg"
+    assert logo.filename == "A.jpg"
+    assert logo.size == (1200, 600)
+    assert logo.cm == approx((4.0, 3.0), 0.01)
+
+
+def test_get_png_without_data(create_dept, create_logos):
+    logo = find_logo("D", dept_id=None)
+    assert logo is not None
+    logo.select()
+    assert logo.logoname == "D"
+    assert logo.suffix == "png"
+    assert logo.filename == "D.png"
+    assert logo.size == (121, 121)
+    assert logo.density is None
+    assert logo.cm is None
+
+
+def test_create_globale_jpg_logo(create_dept, create_logos):
+    path = Path(f"{RESOURCES_DIR}/logo_C.jpg")
+    logo = Logo("X")  # create global logo
+    stream = path.open("rb")
+
+
+def test_create_jpg_instead_of_png_logo(create_dept, create_logos):
+    # action
+    logo = Logo("D")  # create global logo (replace logo_D.png)
+    path = Path(f"{RESOURCES_DIR}/logo_C.jpg")
+    stream = path.open("rb")
+    logo.create(stream)
+    # test
+    created = Path(f"{scu.SCODOC_LOGOS_DIR}/logo_D.jpg")
+    removed = Path(f"{scu.SCODOC_LOGOS_DIR}/logo_D.png")
+    # file system check
+    assert created.exists()
+    assert not removed.exists()
+    # logo check
+    logo = find_logo("D")
+    assert logo is not None
+    assert logo.filepath == f"{scu.SCODOC_LOGOS_DIR}/logo_D.jpg"  # created.absolute()
+    # restore initial state
+    original = Path(f"{RESOURCES_DIR}/logo_D.png")
+    copy(original, removed)
+    created.unlink(missing_ok=True)
+
+
+def test_list_logo(create_dept, create_logos):
+    # test only existence of copied logos. We assumes that they are OK
+    dept1, dept2 = create_dept
+    logos = list_logos()
+    assert logos.keys() == {"_GLOBAL", "RT", "INFO"}
+    assert {"A", "C", "D", "E", "F", "header", "footer"}.issubset(
+        set(logos["_GLOBAL"].keys())
+    )
+    rt = logos.get("RT", None)
+    assert rt is not None
+    assert {"A", "B"}.issubset(set(rt.keys()))
+    info = logos.get("INFO", None)
+    assert info is not None
+    assert {"A"}.issubset(set(rt.keys()))