Merge pull request #66 from wangg12/master

add bgr2hls and hls2bgr

mmcv/image/__init__.py

 from .io import imread, imwrite, imfrombytes
 from .transforms import (bgr2gray, gray2bgr, bgr2rgb, rgb2bgr, bgr2hsv,
-                         hsv2bgr, iminvert, imflip, imrotate, imcrop, impad,
-                         impad_to_multiple, imnormalize, imdenormalize,
-                         imresize, imresize_like, imrescale)
+                         hsv2bgr, bgr2hls, hls2bgr, iminvert, imflip, imrotate,
+                         imcrop, impad, impad_to_multiple, imnormalize,
+                         imdenormalize, imresize, imresize_like, imrescale)
 
 __all__ = [
     'imread', 'imwrite', 'imfrombytes', 'bgr2gray', 'gray2bgr', 'bgr2rgb',
-    'rgb2bgr', 'bgr2hsv', 'hsv2bgr', 'iminvert', 'imflip', 'imrotate',
-    'imcrop', 'impad', 'impad_to_multiple', 'imnormalize', 'imdenormalize',
-    'imresize', 'imresize_like', 'imrescale'
+    'rgb2bgr', 'bgr2hsv', 'hsv2bgr', 'bgr2hls', 'hls2bgr', 'iminvert',
+    'imflip', 'imrotate', 'imcrop', 'impad', 'impad_to_multiple',
+    'imnormalize', 'imdenormalize', 'imresize', 'imresize_like', 'imrescale'
 ]

mmcv/image/transforms/__init__.py

 from .colorspace import (bgr2gray, gray2bgr, bgr2rgb, rgb2bgr, bgr2hsv,
-                         hsv2bgr, iminvert)
+                         hsv2bgr, bgr2hls, hls2bgr, iminvert)
 from .geometry import imflip, imrotate, imcrop, impad, impad_to_multiple
 from .normalize import imnormalize, imdenormalize
 from .resize import imresize, imresize_like, imrescale
 
 __all__ = [
     'bgr2gray', 'gray2bgr', 'bgr2rgb', 'rgb2bgr', 'bgr2hsv', 'hsv2bgr',
-    'iminvert', 'imflip', 'imrotate', 'imcrop', 'impad', 'impad_to_multiple',
-    'imnormalize', 'imdenormalize', 'imresize', 'imresize_like', 'imrescale'
+    'bgr2hls', 'hls2bgr', 'iminvert', 'imflip', 'imrotate', 'imcrop', 'impad',
+    'impad_to_multiple', 'imnormalize', 'imdenormalize', 'imresize',
+    'imresize_like', 'imrescale'
 ]

mmcv/image/transforms/colorspace.py

@@ -71,3 +71,7 @@ rgb2bgr = convert_color_factory('rgb', 'bgr')
 bgr2hsv = convert_color_factory('bgr', 'hsv')
 
 hsv2bgr = convert_color_factory('hsv', 'bgr')
+
+bgr2hls = convert_color_factory('bgr', 'hls')
+
+hls2bgr = convert_color_factory('hls', 'bgr')

tests/test_image.py

@@ -110,6 +110,37 @@ class TestImage(object):
                 computed_hsv[i, j, :] = [h, s, v]
         assert_array_almost_equal(out_img, computed_hsv, decimal=2)
 
+    def test_bgr2hls(self):
+        in_img = np.random.rand(10, 10, 3).astype(np.float32)
+        out_img = mmcv.bgr2hls(in_img)
+        argmax = in_img.argmax(axis=2)
+        computed_hls = np.empty_like(in_img, dtype=in_img.dtype)
+        for i in range(in_img.shape[0]):
+            for j in range(in_img.shape[1]):
+                b = in_img[i, j, 0]
+                g = in_img[i, j, 1]
+                r = in_img[i, j, 2]
+                maxc = max(r, g, b)
+                minc = min(r, g, b)
+                _l = (minc + maxc) / 2.0
+                if minc == maxc:
+                    h = 0.0
+                    s = 0.0
+                if _l <= 0.5:
+                    s = (maxc - minc) / (maxc + minc)
+                else:
+                    s = (maxc - minc) / (2.0 - maxc - minc)
+                if argmax[i, j] == 2:
+                    h = 60 * (g - b) / (maxc - minc)
+                elif argmax[i, j] == 1:
+                    h = 60 * (2.0 + (b - r) / (maxc - minc))
+                else:
+                    h = 60 * (4.0 + (r - g) / (maxc - minc))
+                if h < 0:
+                    h += 360
+                computed_hls[i, j, :] = [h, _l, s]
+        assert_array_almost_equal(out_img, computed_hls, decimal=2)
+
     def test_imresize(self):
         resized_img = mmcv.imresize(self.img, (1000, 600))
         assert resized_img.shape == (600, 1000, 3)