Merge pull request #39 from relic-se/contrast-getter

Fix contrast property read

Author: FoamyGuy

adafruit_ov5640/__init__.py

@@ -1510,11 +1510,15 @@ def brightness(self, value: int) -> None:
     @property
     def contrast(self) -> int:
         """Sensor contrast adjustment, from -3 to 3 inclusive"""
-        contrast_abs = self._read_register(0x5587) >> 4
-        contrast_neg = self._read_register(0x5588) & 8
-        if contrast_neg:
-            return -contrast_abs
-        return contrast_abs
+        try:
+            value = _contrast_settings.index(
+                [self._read_register(0x5586), self._read_register(0x5585)]
+            )
+        except ValueError:
+            value = 0
+        if value > 3:
+            value -= len(_contrast_settings)
+        return value
 
     @contrast.setter
     def contrast(self, value: int) -> None: