feat: added color adjustment feature (#409)

Closes #380

### Summary of Changes
Added the color adjustment feature analogous to the previous image
tasks.

---------

Co-authored-by: megalinter-bot <[email protected]>

Author: patrikguempel

src/safeds/data/image/containers/_image.py

@@ -334,6 +334,36 @@ def adjust_contrast(self, factor: float) -> Image:
         image_copy._image = ImageEnhance.Contrast(image_copy._image).enhance(factor)
         return image_copy
 
+    def adjust_color_balance(self, factor: float) -> Image:
+        """
+        Adjust the image's color balance.
+
+        Parameters
+        ----------
+        factor: float
+            If factor > 1, increase color balance of image.
+            If factor = 1, no changes will be made.
+            If factor < 1, make image greyer.
+            Has to be bigger than or equal to 0.
+
+        Returns
+        -------
+        image: Image
+            The new, adjusted image.
+        """
+        if factor < 0:
+            raise ValueError("Color factor has to be 0 or bigger.")
+        elif factor == 1:
+            warnings.warn(
+                "Color adjustment factor is 1.0, this will not make changes to the image.",
+                UserWarning,
+                stacklevel=2,
+            )
+
+        image_copy = copy.deepcopy(self)
+        image_copy._image = ImageEnhance.Color(image_copy._image).enhance(factor)
+        return image_copy
+
     def blur(self, radius: int) -> Image:
         """
         Return the blurred image.

tests/resources/image/adjusted_colors/by_0.5.png

@@ -324,6 +324,65 @@ def test_should_invert_colors(self, image: Image, expected: Image) -> None:
         assert image == expected
 
 
+class TestColorAdjust:
+    @pytest.mark.parametrize(
+        ("image", "factor", "expected"),
+        [
+            (
+                Image.from_png_file(resolve_resource_path("image/original.png")),
+                2,
+                Image.from_png_file(resolve_resource_path("image/adjusted_colors/by_2.png")),
+            ),
+            (
+                Image.from_png_file(resolve_resource_path("image/original.png")),
+                0.5,
+                Image.from_png_file(resolve_resource_path("image/adjusted_colors/by_0.5.png")),
+            ),
+            (
+                Image.from_png_file(resolve_resource_path("image/original.png")),
+                0,
+                Image.from_png_file(resolve_resource_path("image/adjusted_colors/by_0.png")),
+            ),
+        ],
+        ids=["add color", "remove color", "remove all color"],
+    )
+    def test_should_adjust_colors(self, image: Image, factor: float, expected: Image) -> None:
+        image = image.adjust_color_balance(factor)
+        assert image == expected
+
+    @pytest.mark.parametrize(
+        ("image", "factor"),
+        [
+            (
+                Image.from_png_file(resolve_resource_path("image/original.png")),
+                -1,
+            ),
+        ],
+        ids=["negative"],
+    )
+    def test_should_throw(self, image: Image, factor: float) -> None:
+        with pytest.raises(ValueError, match="Color factor has to be 0 or bigger."):
+            image.adjust_color_balance(factor)
+
+    @pytest.mark.parametrize(
+        ("image", "factor"),
+        [
+            (
+                Image.from_png_file(resolve_resource_path("image/original.png")),
+                1,
+            ),
+        ],
+        ids=["no change"],
+    )
+    def test_should_warn(self, image: Image, factor: float) -> None:
+        with pytest.warns(
+            UserWarning,
+            match="Color adjustment factor is 1.0, this will not make changes to the image.",
+        ):
+            adjust = image.adjust_color_balance(factor)
+        assert adjust == image
+
+
 class TestBlur:
     @pytest.mark.parametrize(
         ("image", "expected"),