[Experimental] Fix image test (#4618)

* Fix test_image.py

* Make test_invert_image use the full range of possible RGB values

manim/mobject/types/image_mobject.py

@@ -26,8 +26,6 @@ from ...utils.color import (
 )
 from ...utils.images import change_to_rgba_array, get_full_raster_image_path
 
-__all__ = ["ImageMobject", "ImageMobjectFromCamera"]
-
 if TYPE_CHECKING:
     from typing import Self
 
@@ -35,8 +33,6 @@ if TYPE_CHECKING:
 
     from manim.typing import PixelArray, StrPath
 
-    from ...camera.moving_camera import MovingCamera
-
 
 class AbstractImageMobject(Mobject):
     """
@@ -216,6 +212,10 @@ class ImageMobject(AbstractImageMobject):
         """A simple getter method."""
         return self.pixel_array
 
+    def init_colors(self) -> None:
+        """Override base init_colors to avoid overwriting image pixels during init."""
+        return None
+
     def set_color(  # type: ignore[override]
         self,
         color: ParsableManimColor = YELLOW_C,

tests/module/mobject/test_image.py

@@ -7,7 +7,7 @@ from manim import ImageMobject
 @pytest.mark.parametrize("dtype", [np.uint8, np.uint16])
 def test_invert_image(dtype):
     rng = np.random.default_rng()
-    array = (255 * rng.random((10, 10, 4))).astype(dtype)
+    array = (np.iinfo(dtype).max * rng.random((10, 10, 4))).astype(dtype)
     image = ImageMobject(array, pixel_array_dtype=dtype, invert=True)
     assert image.pixel_array.dtype == dtype