`ultralytics 8.3.79` Fix shift in HSV augmentation (#19311)

Signed-off-by: Mohammed Yasin <32206511+Y-T-G@users.noreply.github.com>
Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: Mohammed Yasin <32206511+Y-T-G@users.noreply.github.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Laughing-q <1185102784@qq.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: JacekMaksymiuk <32569908+JacekMaksymiuk@users.noreply.github.com>
Co-authored-by: Ultralytics AI Assistant <135830346+UltralyticsAssistant@users.noreply.github.com>
Co-authored-by: Laughing <61612323+Laughing-q@users.noreply.github.com>

ultralytics/__init__.py

@@ -1,6 +1,6 @@
 # Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license
 
-__version__ = "8.3.78"
+__version__ = "8.3.79"
 
 import os
 

ultralytics/data/augment.py

@@ -1364,17 +1364,26 @@ class RandomHSV:
             >>> hsv_augmenter(labels)
             >>> augmented_img = labels["img"]
         """
-        img = labels["img"]
         if self.hgain or self.sgain or self.vgain:
-            r = np.random.uniform(-1, 1, 3) * [self.hgain, self.sgain, self.vgain] + 1  # random gains
-            hue, sat, val = cv2.split(cv2.cvtColor(img, cv2.COLOR_BGR2HSV))
+            img = labels["img"]
             dtype = img.dtype  # uint8
 
+            # Original implementation (bug) from ultralytics<=8.3.78
+            # r = np.random.uniform(-1, 1, 3) * [self.hgain, self.sgain, self.vgain] + 1  # random gains
+            # x = np.arange(0, 256, dtype=r.dtype)
+            # lut_hue = ((x * r[0]) % 180).astype(dtype)
+            # lut_sat = np.clip(x * r[1], 0, 255).astype(dtype)
+            # lut_val = np.clip(x * r[2], 0, 255).astype(dtype)
+
+            # Fixed implementation in https://github.com/ultralytics/ultralytics/pull/19311
+            r = np.random.uniform(-1, 1, 3) * (self.hgain, self.sgain, self.vgain) * (180, 255, 255)  # random gains
             x = np.arange(0, 256, dtype=r.dtype)
-            lut_hue = ((x * r[0]) % 180).astype(dtype)
-            lut_sat = np.clip(x * r[1], 0, 255).astype(dtype)
-            lut_val = np.clip(x * r[2], 0, 255).astype(dtype)
+            lut_hue = ((x + r[0]) % 180).astype(dtype)
+            lut_sat = np.clip(x + r[1], 0, 255).astype(dtype)
+            lut_val = np.clip(x + r[2], 0, 255).astype(dtype)
+            lut_sat[0] = 0  # prevent pure white changing color
 
+            hue, sat, val = cv2.split(cv2.cvtColor(img, cv2.COLOR_BGR2HSV))
             im_hsv = cv2.merge((cv2.LUT(hue, lut_hue), cv2.LUT(sat, lut_sat), cv2.LUT(val, lut_val)))
             cv2.cvtColor(im_hsv, cv2.COLOR_HSV2BGR, dst=img)  # no return needed
         return labels