By default the caption is a bright white when above or below the image.
When in dark mode the caption is a dark grey when position above or below the image.
By default the caption turns slightly transparent when positioned over an image.
When on top of the image the dark grey turns slightly transparent.
By default the caption is tuned down in brightness when the caption is blurred.
If the background of the dark caption is blurred the dark tone is tuned a bit brighter.