expose lab/lch conversion

skimage/color/__init__.py

@@ -15,6 +15,8 @@ from .colorconv import (convert_colorspace,
                         rgb2lab,
                         rgb2hed,
                         hed2rgb,
+                        lab2lch,
+                        lch2lab,
                         separate_stains,
                         combine_stains,
                         rgb_from_hed,
@@ -68,6 +70,8 @@ __all__ = ['convert_colorspace',
            'rgb2lab',
            'rgb2hed',
            'hed2rgb',
+           'lab2lch',
+           'lch2lab',
            'separate_stains',
            'combine_stains',
            'rgb_from_hed',

skimage/color/tests/test_colorconv.py

@@ -34,6 +34,7 @@ from skimage.color import (rgb2hsv, hsv2rgb,
                            xyz2lab, lab2xyz,
                            lab2rgb, rgb2lab,
                            is_rgb, is_gray,
+                           lab2lch, lch2lab,
                            guess_spatial_dimensions
                            )
 
@@ -249,6 +250,13 @@ class TestColorconv(TestCase):
         img_rgb = img_as_float(self.img_rgb)
         assert_array_almost_equal(lab2rgb(rgb2lab(img_rgb)), img_rgb)
 
+    def test_lab_lch_roundtrip(self):
+        rgb = img_as_float(self.img_rgb)
+        lab = rgb2lab(rgb)
+        lab2 = lch2lab(lab2lch(lab))
+        assert_array_almost_equal(lab2, lab)
+
+
 def test_gray2rgb():
     x = np.array([0, 0.5, 1])
     assert_raises(ValueError, gray2rgb, x)