Merge 84ae90e into b6f9fe8

src/histolab/filters/image_filters.py

@@ -185,6 +185,43 @@ def __repr__(self) -> str:
         return self.__class__.__name__ + "()"
 
 
+class RgbToLab:
+    """Convert from the sRGB color space to the CIE Lab colorspace.
+
+    sRGB color space reference: IEC 61966-2-1:1999
+
+    Parameters
+    ----------
+    img : PIL.Image.Image
+        Input image
+    illuminant : {“A”, “D50”, “D55”, “D65”, “D75”, “E”}, optional
+        The name of the illuminant (the function is NOT case sensitive).
+    observer : {“2”, “10”}, optional
+        The aperture angle of the observer.
+
+    Returns
+    -------
+    PIL.Image.Image
+        Image in LAB space
+
+    Raises
+    ------
+    Exception
+        If the image mode is not RGB
+    """
+
+    def __init__(self, illuminant: str = "D65", observer: int = "2") -> None:
+        self.illuminant = illuminant
+        self.observer = observer
+
+    def __call__(self, img: PIL.Image.Image) -> PIL.Image.Image:
+        lab = F.rgb_to_lab(img)
+        return lab
+
+    def __repr__(self) -> str:
+        return self.__class__.__name__ + "()"
+
+
 class HematoxylinChannel:
     """Obtain Hematoxylin channel from RGB image.
 

src/histolab/filters/image_filters_functional.py

@@ -468,6 +468,11 @@ def rgb_to_hsv(img: PIL.Image.Image) -> PIL.Image.Image:
     -------
     PIL.Image.Image
         Image in HED space
+
+    Raises
+    ------
+    Exception
+        If the image mode is not RGB
     """
     if img.mode != "RGB":
         raise Exception("Input image must be RGB")
@@ -477,6 +482,40 @@ def rgb_to_hsv(img: PIL.Image.Image) -> PIL.Image.Image:
     return hsv
 
 
+def rgb_to_lab(
+    img: PIL.Image.Image, illuminant: str = "D65", observer: int = "2"
+) -> PIL.Image.Image:
+    """Convert from the sRGB color space to the CIE Lab colorspace.
+
+    sRGB color space reference: IEC 61966-2-1:1999
+
+    Parameters
+    ----------
+    img : PIL.Image.Image
+        Input image
+    illuminant : {“A”, “D50”, “D55”, “D65”, “D75”, “E”}, optional
+        The name of the illuminant (the function is NOT case sensitive).
+    observer : {“2”, “10”}, optional
+        The aperture angle of the observer.
+
+    Returns
+    -------
+    PIL.Image.Image
+        Image in LAB space
+
+    Raises
+    ------
+    Exception
+        If the image mode is not RGB
+    """
+    if img.mode != "RGB":
+        raise Exception("Input image must be RGB")
+    img_arr = np.array(img)
+    lab_arr = sk_color.rgb2lab(img_arr)
+    lab = np_to_pil(lab_arr)
+    return lab
+
+
 def stretch_contrast(
     img: PIL.Image.Image, low: int = 40, high: int = 60
 ) -> PIL.Image.Image:

tests/integration/test_image_filters.py

@@ -1650,3 +1650,40 @@ def test_yen_threshold_filter_on_gs_image():
     yen_threshold_mask = imf.yen_threshold(gs_img)
 
     np.testing.assert_array_equal(yen_threshold_mask, expected_value)
+
+
+@pytest.mark.parametrize(
+    "pil_image, expected_image",
+    (
+        (
+            RGB.DIAGNOSTIC_SLIDE_THUMB_RGB,
+            "pil-images-rgb/diagnostic-slide-thumb-rgb-to-lab",
+        ),
+        (
+            RGB.DIAGNOSTIC_SLIDE_THUMB_HSV,
+            "pil-images-rgb/diagnostic-slide-thumb-hsv-rgb-to-lab",
+        ),
+        (
+            RGB.DIAGNOSTIC_SLIDE_THUMB_YCBCR,
+            "pil-images-rgb/diagnostic-slide-thumb-ycbcr-rgb-to-lab",
+        ),
+    ),
+)
+def test_rgb_to_lab_filter_with_rgb_image(pil_image, expected_image):
+    expected_value = load_expectation(expected_image, type_="png")
+
+    lab_img = imf.rgb_to_lab(pil_image)
+
+    np.testing.assert_array_almost_equal(np.array(lab_img), np.array(expected_value))
+    assert np.unique(np.array(ImageChops.difference(lab_img, expected_value)))[0] == 0
+
+
+@pytest.mark.parametrize(
+    "pil_image", (RGBA.DIAGNOSTIC_SLIDE_THUMB, GS.DIAGNOSTIC_SLIDE_THUMB_GS),
+)
+def test_rgb_to_lab_raises_exception_on_gs_and_rgba_image(pil_image):
+    with pytest.raises(Exception) as err:
+        imf.rgb_to_lab(pil_image)
+
+    assert isinstance(err.value, Exception)
+    assert str(err.value) == "Input image must be RGB"

tests/unit/filters/test_image_filters.py

@@ -4,6 +4,7 @@
 
 import numpy as np
 import PIL
+
 from histolab.filters import image_filters as imf
 
 from ...unitutil import PILIMG, NpArrayMock, function_mock
@@ -407,3 +408,16 @@ def it_calls_yen_threshold(self, request):
 
         F_yen_threshold.assert_called_once_with(image, operator.lt)
         assert type(yen_threshold(image)) == np.ndarray
+
+    def it_calls_rgb_to_lab_functional(self, request):
+        image = PILIMG.RGBA_COLOR_500X500_155_249_240
+        F_rgb_to_lab = function_mock(
+            request, "histolab.filters.image_filters_functional.rgb_to_lab"
+        )
+        F_rgb_to_lab.return_value = image
+        rgb_to_lab = imf.RgbToLab()
+
+        rgb_to_lab(image)
+
+        F_rgb_to_lab.assert_called_once_with(image)
+        assert type(rgb_to_lab(image)) == PIL.Image.Image